Mentor Graphics 6.2g ModelSim simulation software User’s Manual
Reklamë
Reklamë
ModelSim
®
User’s Manual
Software Version 6.2g
February 2007
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Table of Contents
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Table of Contents
Dragging and Dropping Objects into the Wave and List Windows . . . . . . . . . . . . . . . . . .
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Table of Contents
Using STD_INPUT and STD_OUTPUT Within the Tool . . . . . . . . . . . . . . . . . . . . . . . . . 119
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List of Examples
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List of Figures
15
Figure 2-10. List Window Docked in Main Window MDI Frame . . . . . . . . . . . . . . . . . . . .
60
Figure 2-24. Inserting Module Statement from Verilog Language Template . . . . . . . . . . . .
Figure 2-26. Preferences Dialog for Customizing Source Window . . . . . . . . . . . . . . . . . . .
Figure 3-6. Right-click Compile Menu in Project Tab of Workspace. . . . . . . . . . . . . . . . . .
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List of Figures
Figure 8-12. Grid & Timeline Tab of Wave Window Preferences Dialog . . . . . . . . . . . . . . 204
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List of Figures
Figure 9-3. Wave Viewer Displays Inputs and Outputs of Selected Process . . . . . . . . . . . . 229
Figure 9-4. Unknown States Shown as Red Lines in Wave Window . . . . . . . . . . . . . . . . . . 231
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List of Tables
Table 2-10. Wave Window Toolbar Buttons and Menu Selections . . . . . . . . . . . . . . . . . . .
Table 10-1. Signal Spy: Mapping VHDL Procedures to Verilog System Tasks . . . . . . . . . 239
Table 11-3. Matching SDF INTERCONNECT and PORT to Verilog . . . . . . . . . . . . . . . . 268
Table 11-4. Matching SDF PATHPULSE and GLOBALPATHPULSE to Verilog . . . . . . 269
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List of Tables
Table 12-3. VCD Commands and System Tasks for Multiple VCD Files . . . . . . . . . . . . . . 282
Table 13-8. Commands for Handling Breakpoints and Errors in Macros . . . . . . . . . . . . . . 310
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List of Tables
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Chapter 1
Introduction
This documentation was written for UNIX, Linux, and Microsoft Windows users. Not all versions of ModelSim are supported on all platforms. Contact your Mentor Graphics sales representative for details.
Tool Structure and Flow
The diagram below illustrates the structure of the ModelSim tool, and the flow of that tool as it is used to verify a design.
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Introduction
Simulation Task Overview
Figure 1-1. Tool Structure and Flow
VHDL
Design
Libraries
Vendor
Libraries
vlib vmap
local work library
Map libraries
Design files
.ini or
.mpf file
vlog/ vcom
Analyze/
Compile
Verilog/VHDL
Analyze/
Compile
compiled database
vsim
Interactive Debugging activities i.e.
Simulation Output
(e.g., vcd)
Post-processing Debug
Simulate
Debug
Simulation Task Overview
The following table provides a reference for the tasks required for compiling, loading, and simulating a design in ModelSim.
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Introduction
Basic Steps for Simulation
Task
Step 1:
Map libraries
Step 2:
Compile the design
Example Command Line
Entry
Table 1-1. Simulation Tasks
GUI Menu Pull-down GUI Icons
vlib <library_name>
vmap work <library_name>
vlog file1.v file2.v ...
(Verilog)
vcom file1.vhd file2.vhd ...
(VHDL) a. File > New > Project b. Enter library name c. Add design files to project a. Compile > Compile or
Compile > Compile All
N/A
Compile or
Compile All
icons:
Step 3:
Load the design into the simulator
vsim <top> or
vsim <opt_name>
Step 4:
Run the simulation run step a. Simulate > Start
Simulation
b. Click on top design module or optimized design unit name c. Click OK
This action loads the design for simulation
Simulate > Run
Simulate icon:
Run, or
Run continue, or
Run -all icons:
Step 5:
Debug the design
Common debugging commands: bp describe drivers examine force log show
N/A
N/A
Basic Steps for Simulation
This section provides further detail related to each step in the process of simulating your design using ModelSim.
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Introduction
Basic Steps for Simulation
Step 1 — Collecting Files and Mapping Libraries
Files needed to run ModelSim on your design:
• design files (VHDL and/or Verilog ), including stimulus for the design
• libraries, both working and resource
• modelsim.ini (automatically created by the library mapping command
Providing Stimulus to the Design
You can provide stimulus to your design in several ways:
•
Language based testbench
•
Tcl-based ModelSim interactive command, force
•
VCD files / commands
See
Using Extended VCD as Stimulus
•
3rd party testbench generation tools
What is a Library?
A library is a location where data to be used for simulation is stored. Libraries are ModelSim’s way of managing the creation of data before it is needed for use in simulation. It also serves as a way to streamline simulation invocation. Instead of compiling all design data each and every time you simulate, ModelSim uses binary pre-compiled data from these libraries. So, if you make a changes to a single Verilog module, only that module is recompiled, rather than all modules in the design.
Working and Resource Libraries
Design libraries can be used in two ways: 1) as a local working library that contains the compiled version of your design; 2) as a resource library. The contents of your working library will change as you update your design and recompile. A resource library is typically unchanging, and serves as a parts source for your design. Examples of resource libraries might be: shared information within your group, vendor libraries, packages, or previously compiled elements of your own working design. You can create your own resource libraries, or they may be supplied by another design team or a third party (e.g., a silicon vendor).
For more information on resource libraries and working libraries, see
Working with Design Libraries , and
Specifying the Resource Libraries .
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Introduction
Basic Steps for Simulation
Creating the Logical Library (vlib)
Before you can compile your source files, you must create a library in which to store the compilation results. You can create the logical library using the GUI, using File > New >
Library (see
Creating a Library ), or you can use the
vlib command. For example, the command: vlib work creates a library named work. By default, compilation results are stored in the work library.
Mapping the Logical Work to the Physical Work Directory (vmap)
VHDL uses logical library names that can be mapped to ModelSim library directories. If libraries are not mapped properly, and you invoke your simulation, necessary components will not be loaded and simulation will fail. Similarly, compilation can also depend on proper library mapping.
By default, ModelSim can find libraries in your current directory (assuming they have the right name), but for it to find libraries located elsewhere, you need to map a logical library name to the pathname of the library.
You can use the GUI (
, a command (
Command Line ), or a project (
to assign a logical name to a design library.
The format for command line entry is: vmap <logical_name> <directory_pathname>
This command sets the mapping between a logical library name and a directory.
Step 2 — Compiling the Design (vlog, vcom, sccom)
Designs are compiled with one of the three language compilers.
Compiling Verilog (vlog)
ModelSim’s compiler for the Verilog modules in your design is vlog . Verilog files may be compiled in any order, as they are not order dependent. See
for details.
Compiling VHDL (vcom)
ModelSim’s compiler for VHDL design units is vcom . VHDL files must be compiled according to the design requirements of the design. Projects may assist you in determining the compile order: for more information, see
for details. on VHDL compilation.
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Introduction
Basic Steps for Simulation
Step 3 — Loading the Design for Simulation
vsim topLevelModule
Your design is ready for simulation after it has been compiled. You may then invoke vsim with the names of the top-level modules (many designs contain only one top-level module). For example, if your top-level modules are "testbench" and "globals", then invoke the simulator as follows: vsim testbench globals
After the simulator loads the top-level modules, it iteratively loads the instantiated modules and
UDPs in the design hierarchy, linking the design together by connecting the ports and resolving hierarchical references.
Using SDF
You can incorporate actual delay values to the simulation by applying SDF back-annotation files to the design. For more information on how SDF is used in the design, see
Step 4 — Simulating the Design
Once the design has been successfully loaded, the simulation time is set to zero, and you must enter a run command to begin simulation. For more information, see
SystemVerilog Simulation , and
.
The basic simulator commands are:
• add wave
• force
• bp
• run
• step
Step 5 — Debugging the Design
Numerous tools and windows useful in debugging your design are available from the ModelSim
GUI. In addition, several basic simulation commands are available from the command line to assist you in debugging your design:
• describe
• drivers
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Introduction
Modes of Operation
• examine
• force
• log
• show
Modes of Operation
Many users run ModelSim interactively–pushing buttons and/or pulling down menus in a series of windows in the GUI (graphical user interface). But there are really three modes of ModelSim operation, the characteristics of which are outlined in the following table.:
Table 1-2. Use Modes
Characteristics How ModelSim is invoked ModelSim use mode
GUI
Command-line
Batch
interactive; has graphical windows, push-buttons, menus, and a command line in the transcript.
Default mode interactive command line; no GUI via a desktop icon or from the OS command shell prompt. Example:
OS> vsim non-interactive batch script; no windows or interactive command line with -c argument at the OS command prompt.
Example:
OS> vsim -c at OS command shell prompt using redirection of standard input. Example:
C:\ vsim vfiles.v <infile >outfile
The ModelSim User’s Manual focuses primarily on the GUI mode of operation. However, this section provides an introduction to the Command-line and Batch modes.
Command Line Mode
In command line mode ModelSim executes any startup command specified by the
variable in the modelsim.ini file. If vsim is invoked with the -do "command_string" option, a
DO file (macro) is called. A DO file executed in this manner will override any startup command in the modelsim.ini file.
During simulation a transcript file is created containing any messages to stdout. A transcript file created in command line mode may be used as a DO file if you invoke the transcript
on
command after the design loads (see the example below). The transcript on command writes all of the commands you invoke to the transcript file. For example, the following series of commands results in a transcript file that can be used for command input if top is re-simulated
(remove the quit -f command from the transcript file if you want to remain in the simulator).
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Introduction
Standards Supported
vsim -c top library and design loading messages… then execute: transcript on force clk 1 50, 0 100 -repeat 100 run 500 run @5000 quit -f
Rename transcript files that you intend to use as DO files. They will be overwritten the next time you run vsim if you don’t rename them. Also, simulator messages are already commented out, but any messages generated from your design (and subsequently written to the transcript file) will cause the simulator to pause. A transcript file that contains only valid simulator commands will work fine; comment out anything else with a "#".
Stand-alone tools pick up project settings in command line mode if they are invoked in the project's root directory. If invoked outside the project directory, stand-alone tools pick up project settings only if you set the MODELSIM environment variable to the path to the project file (<Project_Root_Dir>/<Project_Name>.mpf).
Batch Mode
Batch mode is an operational mode that provides neither an interactive command line nor interactive windows. In a Windows environment, vsim is run from a Windows command prompt and standard input and output are redirected from and to files.
Here is an example of a batch mode simulation using redirection of std input and output: vsim counter < yourfile > outfile where "yourfile" is a script containing various ModelSim commands.
You can use the CTRL-C keyboard interrupt to break batch simulation in UNIX and Windows environments.
Standards Supported
ModelSim VHDL implements the VHDL language as defined by IEEE Standards 1076-1987,
1076-1993, and 1076-2002. ModelSim also supports the 1164-1993 Standard Multivalue Logic
System for VHDL Interoperability, and the 1076.2-1996 Standard VHDL Mathematical
Packages standards. Any design developed with ModelSim will be compatible with any other
VHDL system that is compliant with the 1076 specs.
ModelSim Verilog implements the Verilog language as defined by the IEEE Std 1364-1995 and
1364-2005. ModelSim Verilog also supports a partial implementation of SystemVerilog P1800-
2005 (see /<install_dir>/modeltech/docs/technotes/sysvlog.note for implementation details).
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Introduction
Assumptions
Both PLI (Programming Language Interface) and VCD (Value Change Dump) are supported for ModelSim users.
In addition, all products support SDF 1.0 through 4.0 (except the NETDELAY statement),
VITAL 2.2b, VITAL’95 – IEEE 1076.4-1995, and VITAL 2000 – IEEE 1076.4-2000.
Assumptions
We assume that you are familiar with the use of your operating system and its graphical interface.
We also assume that you have a working knowledge of the design languages. Although
ModelSim is an excellent tool to use while learning HDL concepts and practices, this document is not written to support that goal.
Finally, we assume that you have worked the appropriate lessons in the ModelSim Tutorial and are familiar with the basic functionality of ModelSim. The ModelSim Tutorial is available from the ModelSim Help menu.
Sections In This Document
In addition to this introduction, you will find the following major sections in this document:
Chapter
3 , Projects — This chapter discusses ModelSim "projects", a container for
design files and their associated simulation properties.
Chapter
— To simulate an HDL design using ModelSim, you need to know how to create, compile, maintain, and delete design libraries as described in this chapter.
Chapter
5 , VHDL Simulation — This chapter is an overview of compilation and
simulation for VHDL within the ModelSim environment.
Chapter
6 , Verilog and SystemVerilog Simulation — This chapter is an overview of
compilation and simulation for Verilog and SystemVerilog within the ModelSim environment.
Chapter
7 , WLF Files (Datasets) and Virtuals — This chapter describes datasets and
virtuals - both methods for viewing and organizing simulation data in ModelSim.
Chapter
— This chapter describes how to perform waveform analysis with the ModelSim Wave and List windows.
Chapter
9 , Tracing Signals with the Dataflow Window
— This chapter describes how to trace signals and assess causality using the ModelSim Dataflow window.
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Introduction
What is an "Object"
Chapter
— This chapter describes Signal Spy, a set of VHDL procedures and Verilog system tasks that let you monitor, drive, force, or release a design object from anywhere in the hierarchy of a VHDL or mixed design.
Chapter
11 , Standard Delay Format (SDF) Timing Annotation
— This chapter discusses
ModelSim’s implementation of SDF (Standard Delay Format) timing annotation.
Included are sections on VITAL SDF and Verilog SDF, plus troubleshooting.
Chapter
12 , Value Change Dump (VCD) Files — This chapter explains Model
Technology’s Verilog VCD implementation for ModelSim. The VCD usage is extended to include VHDL designs.
Chapter
13 , Tcl and Macros (DO Files) — This chapter provides an overview of Tcl
(tool command language) as used with ModelSim.
Appendix
— This appendix describes environment, system, and preference variables used in ModelSim.
Appendix
C , Error and Warning Messages — This appendix describes ModelSim error
and warning messages.
Appendix
D , Verilog PLI/VPI/DPI — This appendix describes the ModelSim
implementation of the Verilog PLI and VPI.
Appendix
E , Command and Keyboard Shortcuts
— This appendix describes ModelSim keyboard and mouse shortcuts.
Appendix
G , System Initialization — This appendix describes what happens during
ModelSim startup.
What is an "Object"
Because ModelSim works with so many languages (Verilog, VHDL, SystemVerilog, ), an
“object” refers to any valid design element in those languages. The word "object" is used whenever a specific language reference is not needed. Depending on the context, “object” can refer to any of the following:
Language
VHDL
Verilog
SystemVerilog
Table 1-3. Definition of Object by Language
An object can be
block statement, component instantiation, constant, generate statement, generic, package, signal, alias, or variable function, module instantiation, named fork, named begin, net, task, register, or variable
In addition to those listed above for Verilog: class, package, program, interface, array, directive, property, or sequence
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Language
PSL
Table 1-3. Definition of Object by Language
An object can be
property, sequence, directive, or endpoint
Introduction
Text Conventions
Text Conventions
Text conventions used in this manual include:
Text Type
italic text
bold text
monospace type
The right angle (>)
UPPER CASE
Table 1-4. Text Conventions
Description
provides emphasis and sets off filenames, pathnames, and design unit names indicates commands, command options, menu choices, package and library logical names, as well as variables, dialog box selections, and language keywords monospace type is used for program and command examples is used to connect menu choices when traversing menus as in: File > Quit denotes file types used by ModelSim (e.g., DO,
WLF, INI, MPF, PDF, etc.)
Installation Directory Pathnames
When referring to installation paths, this manual uses “modeltech” as a generic representation of the installation directory for all versions of ModelSim. The actual installation directory on your system may contain version information.
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Introduction
Installation Directory Pathnames
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Chapter 2
Simulator Windows
ModelSim’s graphical user interface (GUI) consists of various windows that give access to parts of your design and numerous debugging tools. Some of the windows display as panes within the ModelSim Main window and some display as windows in the Multiple Document
Interface (MDI) frame.
Figure 2-1. Graphical User Interface
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Simulator Windows
The following table summarizes all of the available windows and panes.
Table 2-1. GUI Windows and Panes
Window/pane name Description More details
Main
Active Processes central GUI access point displays all processes that are scheduled to run during the current simulation cycle
Dataflow
List
Locals displays "physical" connectivity and lets you trace events (causality) shows waveform data in a tabular format displays data objects that are immediately visible at the current PC of the selected process
Memory
Watch
Objects
Source
Transcript
Wave
Workspace a Workspace tab and MDI windows that show memories and their contents displays signal or variable values at the current simulation time displays all declared data objects in the current scope a text editor for viewing and editing
HDL, DO, etc. files
keeps a running history of commands and messages and provides a commandline interface
displays waveforms provides easy access to projects, libraries, compiled design units, memories, etc.
The windows and panes are customizable in that you can position and size them as you see fit, and ModelSim will remember your settings upon subsequent invocations. See
Graphic User Interface for more details.
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Simulator Windows
Design Object Icons and Their Meaning
Design Object Icons and Their Meaning
The color and shape of icons convey information about the language and type of a design object. shows the icon colors and the languages they indicate.
Icon color
Table 2-2. Design Object Icons
Design Language
light blue dark blue orange
Verilog or SystemVerilog
VHDL virtual object
Here is a list of icon shapes and the design object types they indicate:
Table 2-3. Icon Shapes and Design Object Types icon shape example design object type
square circle any scope (VHDL block, Verilog named block, SC module, class, interface, task, function, etc.) process diamond valued object (signals, nets, registers, etc.) caution sign diamond with red dot star comparison object an editable waveform created with the waveform editor transaction; The color of the star for each transaction depends on the language of the region in which the transaction stream occurs: dark blue for VHDL, light blue for Verilog and SystemVerilog, green for SystemC, magenta for PSL.
Setting Fonts
You may need to adjust font settings to accommodate the aspect ratios of wide screen and double screen displays or to handle launching ModelSim from an X-session.
Font Scaling
To change font scaling, select Tools > Options > Adjust Font Scaling. You’ll need a ruler to complete the instructions in the lower right corner of the dialog. When you have entered the pixel and inches information, click OK to close the dialog. Then, restart ModelSim to see the change. This is a one time setting; you shouldn't have to set it again unless you change display
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Simulator Windows
Main Window
resolution or the hardware (monitor or video card). The font scaling applies to Windows and
UNIX operating systems. On UNIX systems, the font scaling is stored based on the $DISPLAY environment variable.
Controlling Fonts in an X-session
When executed via an X-session (e.g., Exceed, VNC), ModelSim uses font definitions from the
.Xdefaults file. To ensure that the fonts look correct, create a .Xdefaults file with the following lines: vsim*Font: -adobe-courier-medium-r-normal--*-120-*-*-*-*-* vsim*SystemFont: -adobe-courier-medium-r-normal--*-120-*-*-*-*-* vsim*StandardFont: -adobe-courier-medium-r-normal--*-120-*-*-*-*-* vsim*MenuFont: -adobe-courier-medium-r-normal--*-120-*-*-*-*-*
Alternatively, you can choose a different font. Use the program "xlsfonts" to identify which fonts are available on your system.
Also, the following command can be used to update the X resources if you make changes to the
.Xdefaults and wish to use those changes on a UNIX machine:
xrdb -merge .Xdefaults
Main Window
The primary access point in the ModelSim GUI is called the Main window. It provides convenient access to design libraries and objects, source files, debugging commands, simulation status messages, etc. When you load a design, or bring up debugging tools, ModelSim adds panes or opens windows appropriate for your debugging environment (
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Figure 2-2. Main Window
Simulator Windows
Main Window
Workspace tabs organize design elements in a hierarchical tree structure
The Transcript pane reports status and provides a commandline interface
The Objects pane displays data objects in the current scope
Multiple document interface
(MDI) pane
Notice some of the elements that appear:
•
Workspace tabs organize and display design objects in a hierarchical tree format
•
The Transcript pane tracks command history and messages and provides a commandline interface where you can enter ModelSim commands
•
The Objects pane displays design objects such as signals, nets, generics, etc. in the current design scope
Workspace
The Workspace provides convenient access to projects, libraries, design files, compiled design units, simulation/dataset structures, and Waveform Comparison objects. It can be hidden or displayed by selecting View > Windows > Workspace (Main window).
The Workspace can display the types of tabs listed below.
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Simulator Windows
Main Window
•
Project tab — Shows all files that are included in the open project. Refer to
for details.
•
Library tab — Shows design libraries and compiled design units. To update the current view of the library, select a library, and then Right click > Update. See
Library Contents for details on library management.
•
Structure tabs —Shows a hierarchical view of the active simulation and any open datasets. There is one tab for the current simulation (named "sim") and one tab for each open dataset. See
for details.
An entry is created by each object within the design. When you select a region in a structure tab, it becomes the current region and is highlighted. The
and
Objects Pane change dynamically to reflect the information for the current region. This
feature provides a useful method for finding the source code for a selected region because the system keeps track of the pathname where the source is located and displays it automatically, without the need for you to provide the pathname.
Also, when you select a region in the structure pane, the
updated. The Active Processes window will in turn update the
.
Objects can be dragged from the structure tabs to the Dataflow, List and Wave windows.
You can toggle the display of processes by clicking in a Structure tab and selecting
View > Filter > Processes.
You can also control implicit wire processes using a preference variable. By default
Structure tabs suppress the display of implicit wire processes. To enable the display of implicit wire processes, set PrefMain(HideImplicitWires) to 0 (select Tools > Edit
Preferences, By Name tab, and expand the Main object).
•
Files tab — Shows the source files for the loaded design.
You can disable the display of this tab by setting the PrefMain(ShowFilePane) preference variable to 0. See
Simulator GUI Preferences for information on setting
preference variables.
•
Memories tab — Shows a hierarchical list of all memories in the design. To display this tab, select View > Windows > Memory. When you select a memory on the tab, a memory contents page opens in the MDI frame. See
Transcript
The Transcript portion of the Main window maintains a running history of commands that are invoked and messages that occur as you work with ModelSim. When a simulation is running, the Transcript displays a VSIM prompt, allowing you to enter command-line commands from within the graphic interface.
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Simulator Windows
Main Window
You can scroll backward and forward through the current work history by using the vertical scrollbar. You can also use arrow keys to recall previous commands, or copy and paste using the mouse within the window (see
Main and Source Window Mouse and Keyboard Shortcuts
for details).
Saving the Transcript File
Variable settings determine the filename used for saving the transcript. If either PrefMain(file) in the .modelsim file or TranscriptFile in the modelsim.ini file is set, then the transcript output is logged to the specified file. By default the TranscriptFile variable in modelsim.ini is set to
transcript. If either variable is set, the transcript contents are always saved and no explicit saving is necessary.
If you would like to save an additional copy of the transcript with a different filename, click in the Transcript pane and then select File > Save As, or File > Save. The initial save must be made with the Save As selection, which stores the filename in the Tcl variable
PrefMain(saveFile). Subsequent saves can be made with the Save selection. Since no automatic saves are performed for this file, it is written only when you invoke a Save command.
The file is written to the specified directory and records the contents of the transcript at the time of the save.
Using the Saved Transcript as a Macro (DO file)
Saved transcript files can be used as macros (DO files). Refer to the do command for more information.
Changing the Number of Lines Saved in the Transcript Window
By default, the Transcript window retains the last 5000 lines of output from the transcript. You can change this default by altering the saveLines preference variable. Setting this variable to 0 instructs the tool to retain all lines of the transcript. See
for details on setting preference variables.
Disabling Creation of the Transcript File
You can disable the creation of the transcript file by using the following ModelSim command immediately after ModelSim starts:
transcript file ""
Automatic Command Help
When you start typing a command at the Transcript prompt, a dropdown box appears which lists the available commands matching what has been typed so far. You may use the Up and Down arrow keys or the mouse to select the desired command. When a unique command has been entered, the command usage is presented in the drop down box.
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Main Window
You can disable this feature by selecting Help > Command Completion or by setting the
PrefMain(EnableCommandHelp) preference variable to 0. See
details on setting preference variables.
Message Viewer
The Message Viewer tab, found in the Transcript pane, allows you to easily access, organize, and analyze any Note, Warning, Error or other elaboration and runtime messages written to the transcript during the simulation run.
By default, the tool writes transcripted messages to both the transcript and the WLF file. By writing to the WLF file, the Message Viewer tab is able to organize the messages for your analysis.
Controlling the Message Viewer Data
•
Command Line — The -msgmode argument to vsim controls where the simulator outputs the messages.
vsim -msgmode {both | tran | wlf} where: o both — outputs messages to both the transcript and the WLF file. Default behavior.
o tran — outputs messages only to the transcript, therefore they are not available in the
Message Viewer.
o wlf — outputs messages only to the WLF file/Message Viewer, therefore they are not available in the transcript.
•
modelsim.ini File — The
variable in the modelsim.ini file accepts the same values described above for the -msgmode argument.
Message Viewer Interface and Tasks
The Message Viewer tab does not display by default. You can bring it up after a simulation run with the View > Message Viewer menu item. The message viewer is also automatically displayed when you perform the dataset open command.
Figure 2-3 and Table 2-4 provide an
overview of the Message Viewer and several tasks you can perform.
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Figure 2-3. Message Viewer Tab
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Main Window
Table 2-4. Message Viewer Tasks
Icon Task
1 Display a detailed description of the message.
Action
right click the message text then select View Verbose Message.
2 double click the object name(s).
3
4
Open the source file and add a bookmark to the location of the object(s).
Change the focus of the Workspace and
Objects panes.
Open the source file and set a marker at the line number.
double click the hierarchical reference.
double click the file name.
Multiple Document Interface (MDI) Frame
The MDI frame is an area in the Main window where source editor, memory content, wave, and list windows display. The frame allows multiple windows to be displayed simultaneously, as shown below. A tab appears for each window.
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Organizing Windows with Tab Groups
Figure 2-4. Tabs in the MDI Frame
Object name
Window tabs
The object name is displayed in the title bar at the top of the window. You can switch between the windows by clicking on a tab.
Organizing Windows with Tab Groups
The MDI can quickly become unwieldy if many windows are open. You can create "tab groups" to help organize the windows. A tab group is a collection of tabs that are separated from other groups of tabs.
Figure 2-5 shows how the collection of files in
could be organized into two tab groups.
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Navigating in the Main Window
Figure 2-5. Organizing Files in Tab Groups
The commands for creating and organizing tab groups are accessed by right-clicking on any window tab. The table below describes the commands associated with tab groups:
Command
New Tab Group
Table 2-5. Commands for Tab Groups
Description
Creates a new tab group containing the selected tab
Move Next Group
Move Prev Group
Moves the selected tab to the next group in the
MDI
Moves the selected tab to the previous group in the
MDI
View > Vertical /
Horizontal
Arranges tab groups top-to-bottom (vertical) or right-to-left (horizontal)
Note that you can also move the tabs within a tab group by dragging them with the middle mouse button.
Navigating in the Main Window
The Main window can contain of a number of "panes" and sub-windows that display various types of information about your design, simulation, or debugging session. Here are a few important points to keep in mind about the Main window interface:
•
Windows/panes can be resized, moved, zoomed, undocked, etc. and the changes are persistent.
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Navigating in the Main Window
You have a number of options for re-sizing, re-positioning, undocking/redocking, and generally modifying the physical characteristics of windows and panes.
Windows and panes can be undocked from the main window by pressing the Undock button in the header or by using the view -undock <window_name> command. For example, view -undock objects will undock the Objects window. The default docked or undocked status of each window or pane can be set with the
PrefMain(ViewUnDocked) <window_name> preference variable.
When you exit ModelSim, the current layout is saved so that it appears the same the next time you invoke the tool.
•
Menus are context sensitive.
The menu items that are available and how certain menu items behave depend on which pane or window is active. For example, if the sim tab in the Workspace is active and you choose Edit from the menu bar, the Clear command is disabled. However, if you click in the Transcript pane and choose Edit, the Clear command is enabled. The active pane is denoted by a blue title bar.
For more information, see
Navigating the Graphic User Interface .
Main Window Status Bar
Figure 2-6. Main Window Status Bar
Fields at the bottom of the Main window provide the following information about the current simulation:
Table 2-6. Information Displayed in Status Bar
Field
Project
Now
Delta
Profile Samples
Description
name of the current project the current simulation time the current simulation iteration number the number of profile samples collected during the current simulation
Memory environment line/column the total memory used during the current simulation name of the current context (object selected in the active Structure tab of the Workspace) line and column numbers of the cursor in the active
Source window
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Main Window Toolbar
Buttons on the Main window toolbar give you quick access to various ModelSim commands and functions.
Button
Table 2-7. Main Window Toolbar Buttons
Menu equivalent Command equivalents
New File
create a new source file
File > New > Source
Open
open the Open File dialog
File > Open
Save
save the contents of the active pane
open the Print dialog
Cut
cut the selected text to the clipboard
File > Save
File > Print
Edit > Cut
Copy
copy the selected text to the clipboard
Edit > Copy
Edit > Paste
Paste
paste the clipboard text
Undo
undo the last edit
Edit > Undo
Redo
redo the last undone edit
Find
find text in the active window
Collapse All
collapse all instances in the active window
Expand All
expand all instance in the active window
Edit > Redo
Edit > Find
Edit > Expand > Collapse All
Edit > Expand > Expand All
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Navigating in the Main Window
Button
Table 2-7. Main Window Toolbar Buttons
Menu equivalent
Compile
open the Compile Source Files dialog to select files for compilation
Compile All
compile all files in the open project
Compile > Compile
Compile > Compile All
Command equivalents
vcom vlog vcom vlog
Simulate > Start Simulation vsim
Simulate
load the selected design unit or simulation configuration object
Break
stop the current simulation run
Simulate > Break
Environment up
move up one level in the design hierarchy
Environment back
navigate backward to a previously selected context
Environment forward
navigate forward to a previously selected context
Restart
reload the design elements and reset the simulation time to zero, with the option of maintaining various settings and objects
Run Length
specify the run length for the current simulation
Run
run the current simulation for the specified run length
Simulate > Run > Restart
Simulate > Run >
Run default_run_length restart
Simulate > Runtime Options run run
Continue Run
continue the current simulation run until the end of the specified run length or until it hits a breakpoint or specified break event
Simulate > Run > Continue run
-continue
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Active Processes Pane
Button
Table 2-7. Main Window Toolbar Buttons
Menu equivalent Command equivalents
Simulate > Run > Run -All run -all
Run -All
run the current simulation forever, or until it hits a breakpoint or specified break event
Step
step the current simulation to the next statement
Simulate > Run > Step step step -over
Step Over
HDL statements are executed but treated as simple statements instead of entered and traced line by line
Simulate > Run >
Step -Over
Contains
filter items in Objects pane
Show Language Templates
display language templates
View > Source >
Show Language Templates
Active Processes Pane
The Active Processes pane displays a list of HDL processes. Processes are also displayed in the structure tabs of the Main window Workspace. To filter displayed processes in the structure tabs, select View > Filter > Processes.
Figure 2-7. Active Processes Pane
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Call Stack Pane
Process Status
Each object in the scrollbox is preceded by one of the following indicators:
•
<Ready> — Indicates that the process is scheduled to be executed within the current delta time. If you select a "Ready" process, it will be executed next by the simulator.
•
<Wait> — Indicates that the process is waiting for a VHDL signal or Verilog net or variable to change or for a specified time-out period.
•
<Done> — Indicates that the process has executed a VHDL wait statement without a time-out or a sensitivity list. The process will not restart during the current simulation run.
Call Stack Pane
The Call Stack pane displays the current call stack when you single step your simulation or when the simulation has encountered a breakpoint. When debugging your design, you can use the call stack data to analyze the depth of function calls, which include Verilog functions and tasks and VHDL functions and procedures, that led up to the current point of the simulation.
Accessing the Call Stack Pane
View > Call Stack
Figure 2-8. Call Stack Pane
Using the Call Stack Pane
The Call Stack pane contains five columns of information to assist you in debugging your design:
•
# — indicates the depth of the function call, with the most recent at the top.
•
In — indicates the function.
•
Line — indicates the line number containing the function call.
•
File — indicates the location of the file containing the function call.
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•
Address — indicates the address of the execution in a foreign subprogram, such as C.
The Call Stack pane allows you to perform the following actions within the pane:
•
Double-click on the line of any function call: o
Displays the local variables at that level in the
o
Displays the corresponding source code in the
•
Right-click in the column headings o
Displays a pop-up window that allows you to show or hide columns.
Dataflow Window
The Dataflow window allows you to explore the "physical" connectivity of your design.
Note
OEM versions of ModelSim have limited Dataflow functionality. Many of the features described below will operate differently. The window will show only one process and its attached signals or one signal and its attached processes, as displayed in
.
Figure 2-9. Dataflow Window
The Dataflow window displays:
• processes
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Dataflow Window
• signals, nets, and registers
The window has built-in mappings for all Verilog primitive gates (i.e., AND, OR, PMOS,
NMOS, etc.). For components other than Verilog primitives, you can define a mapping between processes and built-in symbols. See
Dataflow Window Toolbar
The buttons on the Dataflow window toolbar are described below.
Button
Table 2-8. Dataflow Window Toolbar
Menu equivalent
Print — print the current view of the Dataflow window
File > Print (Windows)
File > Print Postscript (UNIX)
Select mode — set left mouse button to select mode and middle mouse button to zoom mode
View > Select
Zoom mode — set left mouse button to zoom mode and middle mouse button to pan mode
Pan mode — set left mouse button to pan mode and middle mouse button to zoom mode
Cut — cut the selected object(s)
View > Zoom
View > Pan
Edit > Cut
Copy — copy the selected object(s)
Paste — paste the previously cut or copied object(s)
Undo — undo the last action
Edit > Copy
Edit > Paste
Edit > Undo
Redo — redo the last undone action
Find — search for an instance or signal
Edit > Redo
Edit > Find
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Button
Table 2-8. Dataflow Window Toolbar
Menu equivalent
Trace > Trace next event Trace input net to event — move the next event cursor to the next input event driving the selected output
Trace Set — jump to the source of the selected input event
Trace > Trace event set
Trace Reset — return the next event cursor to the selected output
Trace > Trace event reset
Trace net to driver of X — step back to the last driver of an unknown value
Trace > TraceX
Expand net to all drivers — display driver(s) of the selected signal, net, or register
Navigate > Expand net to drivers
Expand net to all drivers and readers — display driver(s) and reader(s) of the selected signal, net, or register
Expand net to all readers — display reader(s) of the selected signal, net, or register
Navigate > Expand net
Navigate > Expand net to readers
Erase highlight — clear the green highlighting which identifies the path you’ve traversed through the design
Erase all — clear the window
Edit > Erase highlight
Edit > Erase all
Regenerate — clear and redraw the display using an optimal layout
Edit > Regenerate
Zoom In — zoom in by a factor of two from current view
Zoom Out — zoom out by a factor of two from current view none none
Zoom Full — zoom out to show all components in the window none
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Dataflow Window
Button
Table 2-8. Dataflow Window Toolbar
Stop Drawing — halt any drawing currently happening in the window
Menu equivalent
none
Show Wave — display the embedded wave viewer pane
View > Show Wave
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List Window
List Window
The List window displays the results of your simulation run in tabular format. The window is divided into two adjustable columns, which allow you to scroll horizontally through the listing on the right, while keeping time and delta visible on the left.
The List window opens by default in the MDI frame of the Main window as shown in
Figure 2-10. List Window Docked in Main Window MDI Frame
The window can be undocked from the Main window by clicking the Undock button in the window header or by using the view -undock list command.
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Figure 2-11. List Window Undocked
The following type of objects can be viewed in the List pane:
•
VHDL — signals, aliases, process variables, and shared variables
•
Verilog — nets, registers, and variables
•
Virtuals — Virtual signals and functions
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Locals Pane
Locals Pane
The Locals pane displays data objects that are immediately visible from the statement that will be executed next (that statement is denoted by a blue arrow in the Source editor window). The contents of the window change from one statement to the next.
The Locals pane includes two columns. The first column lists the names of the immediately visible data objects. The second column lists the current value(s) associated with each name.
Figure 2-12. Locals Pane
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Memory Panes
Memory Panes
The Main window lists all memories in your design in the Memories tab of the Main window
Workspace and displays the contents of a selected memory in the Main window MDI frame.
Figure 2-13. Memory Panes
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The memory list is from the top-level of the design. In other words, it is not sensitive to the context selected in the Structure tab.
ModelSim identifies certain kinds of arrays in various scopes as memories. Memory identification depends on the array element kind as well as the overall array kind (i.e.
associative array, unpacked array, etc.).
Element kind
VHDL
Table 2-9. Memories
Verilog/SystemVerilog
enum
1
, std_logic_vector, std_bit_vector, or integer.
any integral type. (i.e. integer_type): shortint, int, longint, byte, bit (2 state), logic, reg, integer, time (4 state), packed_struct / packed_union (2 state), packed_struct / packed_union (4 state), packed_array (single-Dim, multi-D,
2 state and 4 state), enum or string.
Scope: recognizable in architecture, process, or record
Array kind single-dimensional or multi-dimensional module, interface, package, compilation unit, struct, or static variables within a task / function / named block / class any combination of unpacked, dynamic and associative arrays
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1. These enumerated type value sets must have values that are longer than one character. The listed width is the number of entries in the enumerated type definition and the depth is the size of the array itself.
2. Any combination of unpacked, dynamic, and associative arrays is considered a memory, provided the leaf level of the data structure is a string or an integral type.
Associative Arrays in Verilog/SystemVerilog
For an associative array to be recognized as a memory, the index must be of an integral type
(see above) or wildcard type.
For associative arrays, the element kind can be any type allowed for fixed-size arrays.
Viewing Single and Multidimensional Memories
Single dimensional arrays of integers are interpreted as 2D memory arrays. In these cases, the word width listed in the Memory List pane is equal to the integer size, and the depth is the size of the array itself.
Memories with three or more dimensions display with a plus sign ’+’ next to their names in the
Memory List. Click the ’+’ to show the array indices under that level. When you finally expand down to the 2D level, you can double-click on the index, and the data for the selected 2D slice of the memory will appear in a memory contents pane in the MDI frame.
Viewing Packed Arrays
By default packed dimensions are treated as single vectors in the memory contents pane. To expand packed dimensions of packed arrays, select View > Memory Contents > Expand
Packed Memories.
To change the permanent default, edit the PrefMemory(ExpandPackedMem) variable. This variable affects only packed arrays. If the variable is set to 1, the packed arrays are treated as unpacked arrays and are expanded along the packed dimensions such that they appear as a linearized bit vector. See
Simulator GUI Preferences for details on setting preference variables.
Viewing Memory Contents
When you double-click an instance on the Memory tab, ModelSim automatically displays a memory contents pane in the MDI frame (see
Multiple Document Interface (MDI) Frame ). You
can also enter the command add mem <instance> at the vsim command prompt.
Viewing Multiple Memory Instances
You can view multiple memory instances simultaneously. A memory tab appears in the MDI frame for each instance you double-click in the Memory list.
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Memory Panes
Figure 2-14. Viewing Multiple Memories
See
Organizing Windows with Tab Groups for more information on tabs.
Saving Memory Formats in a DO File
You can save all open memory instances and their formats (e.g., address radix, data radix, etc.) by creating a DO file. With the memory tab active, select File > Save As. The Save memory format dialog box opens, where you can specify the name for the saved file. By default it is named mem.do. The file will contain all open memory instances and their formats. To load it at a later time, select File > Load.
Direct Address Navigation
You can navigate to any address location directly by editing the address in the address column.
Double-click on any address, type in the desired address, and hit Enter. The address display scrolls to the specified location.
Splitting the Memory Contents Pane
To split a memory contents window into two screens displaying the contents of a single memory instance, so any one of the following:
• select Memories > Split Screen if the Memory Contents Pane is docked in the Main window,
• select View > Split Screen if the Memory Contents Pane is undocked,
• right-click in the pane and select Split Screen from the pop-up menu.
This allows you to view different address locations within the same memory instance simultaneously.
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Figure 2-15. Split Screen View of Memory Contents
Simulator Windows
Memory Panes
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Objects Pane
Objects Pane
The Objects pane shows the names and current values of declared data objects in the current region (selected in the structure tabs of the Workspace). Data objects include signals, nets, registers, constants and variables not declared in a process, generics, parameters.
Clicking an entry in the window highlights that object in the Dataflow and Wave windows.
Double-clicking an entry highlights that object in a Source editor window (opening a Source editor window if one is not open already). You can also right click an object name and add it to the List or Wave window, or the current log file.
Figure 2-16. Objects Pane
Filtering the Objects List
You can filter the objects list by name or by object type.
Filtering by Name
To filter by name, undock the Objects pane from the Main window and start typing letters in the
Contains field in the toolbar.
Figure 2-17. Objects Filter
As you type, the objects list filters to show only those signals that contain those letters.
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Figure 2-18. Filtering the Objects List by Name
Simulator Windows
Objects Pane
To display all objects again, click the Eraser icon to clear the entry.
Filters are stored relative to the region selected in the Structure window. If you re-select a region that had a filter applied, that filter is restored. This allows you to apply different filters to different regions.
Filtering by Signal Type
The View > Filter menu selection allows you to specify which signal types to display in the
Objects window. Multiple options can be selected.
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Source Window
Source Window
Source files display by default in the MDI frame of the Main window. The window can be undocked from the Main window by pressing the Undock button in the window header or by using the view -undock source command.
You can edit source files as well as set breakpoints, step through design files, and view code coverage statistics.
By default, the Source window displays your source code with line numbers. You may also see the following graphic elements:
•
Red line numbers — denote lines on which you can set a breakpoint
•
Blue arrow — denotes the currently active line or a process that you have selected in the
•
Red circles — denote file-line breakpoints; gray circles denote breakpoints that are currently disabled
•
Blue circles — denote line bookmarks
•
Language Templates pane — displays
Figure 2-19. Source Window Showing Language Templates
Opening Source Files
You can open source files using the File > Open command. Alternatively, you can open source files by double-clicking objects in other windows. For example, if you double-click an item in
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the Objects window or in the structure tab of the Workspace, the underlying source file for the object will open, and the cursor will scroll to the line where the object is defined.
By default files you open from within the design (e.g., by double-clicking an object in the
Objects pane) open in Read Only mode. To make the file editable, right-click in the Source window and select Read Only. To change this default behavior, set the PrefSource(ReadOnly) variable to 0. See
Simulator GUI Preferences for details on setting preference variables.
Displaying Multiple Source Files
By default each file you open or create is marked by a window tab, as shown in the graphic below.
Figure 2-20. Displaying Multiple Source Files
See
Organizing Windows with Tab Groups for more information on these tabs.
Dragging and Dropping Objects into the Wave and List
Windows
ModelSim allows you to drag and drop objects from the Source window to the Wave and List windows. Double-click an object to highlight it, then drag the object to the Wave or List window. To place a group of objects into the Wave and List windows, drag and drop any section of highlighted code.
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Setting your Context by Navigating Source Files
When debugging your design from within the GUI, you can change your context while analyzing your source files.
Figure 2-21 shows the pop-up menu the tool displays after you
select then right-click an instance name in a source file.
Figure 2-21. Setting Context from Source Files
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This functionality allows you to easily navigate your design for debugging purposes by remembering where you have been, similar to the functionality in most web browsers. The navigation options in the pop-up menu function as follows:
•
Open Instance — changes your context to the instance you have selected within the source file. This is not available if you have not placed your cursor in, or highlighted the name of, an instance within your source file.
If any ambiguities exists, most likely due to generate statements, this option opens a dialog box allowing you to choose from all available instances.
•
Ascend Env — changes your context to the next level up within the design. This is not available if you are at the top-level of your design.
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•
Forward/Back — allows you to change to previously selected contexts. This is not available if you have not changed your context.
The Open Instance option is essentially executing an environment command to change your context, therefore any time you use this command manually at the command prompt, that information is also saved for use with the Forward/Back options.
Language Templates
ModelSim language templates help you write code. They are a collection of wizards, menus, and dialogs that produce code for new designs, testbenches, language constructs, logic blocks, etc.
Note
The language templates are not intended to replace thorough knowledge of coding. They are intended as an interactive "reference" for creating small sections of code. If you are unfamiliar with a particular language, you should attend a training class or consult one of the many available books.
To use the templates, either open an existing file, or select File > New > Source to create a new file. Once the file is open, select Source > Show Language Templates if the Source window is docked in the Main window; select View > Show Language Templates of the Source window is undocked. This displays a pane that shows the available templates.
Figure 2-22. Language Templates
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The templates that appear depend on the type of file you create. For example Module and
Primitive templates are available for Verilog files, and Entity and Architecture templates are available for VHDL files.
Double-click an object in the list to open a wizard or to begin creating code. Some of the objects bring up wizards while others insert code into your source file. The dialog below is part of the wizard for creating a new design. Simply follow the directions in the wizards.
Figure 2-23. Create New Design Wizard
Code inserted into your source contains a variety of highlighted fields. The example below shows a module statement inserted from the Verilog template.
Figure 2-24. Inserting Module Statement from Verilog Language Template
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Some of the fields, such as module_name in the example above, are to be replaced with names you type. Other fields can be expanded by double-clicking and still others offer a context menu
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of options when double-clicked. The example below shows the menu that appears when you double-click module_item then select gate_instantiation.
Figure 2-25. Language Template Context Menus
Setting File-Line Breakpoints
You can easily set
File-line breakpoints in a Source window using your mouse. Click on a red
line number at the left side of the Source window, and a red circle denoting a breakpoint will appear. The breakpoints are toggles – click once to create the breakpoint; click again to disable or enable the breakpoint.
To delete the breakpoint completely, right click the red circle, and select Remove Breakpoint.
Other options on the context menu include:
•
Disable/Enable Breakpoint — Deactivate or activate the selected breakpoint.
•
Edit Breakpoint — Open the File Breakpoint dialog to change breakpoint arguments.
•
Edit All Breakpoints — Open the Modify Breakpoints dialog
Checking Object Values and Descriptions
There are two quick methods to determine the value and description of an object displayed in the Source window:
• select an object, then right-click and select Examine or Describe from the context menu
• pause over an object with your mouse pointer to see an examine pop-up
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Select Tools > Options > Examine Now or Tools > Options > Examine Current Cursor to choose at what simulation time the object is examined or described.
You can also invoke the examine and/or describe commands on the command line or in a macro.
Marking Lines with Bookmarks
Source window bookmarks are blue circles that mark lines in a source file. These graphical icons may ease navigation through a large source file by "highlighting" certain lines.
As noted above in the discussion about finding text in the Source window, you can insert bookmarks on any line containing the text for which you are searching. The other method for inserting bookmarks is to right-click a line number and select Add/Remove Bookmark. To remove a bookmark, right-click the line number and select Add/Remove Bookmark again.
Customizing the Source Window
You can customize a variety of settings for Source windows. For example, you can change fonts, spacing, colors, syntax highlighting, and so forth. To customize Source window settings, select Tools > Edit Preferences. This opens the Preferences dialog. Select Source Windows from the Window List.
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Figure 2-26. Preferences Dialog for Customizing Source Window
Select an item from the Category list and then edit the available properties on the right. Click
OK or Apply to accept the changes.
The changes will be active for the next Source window you open. The changes are saved automatically when you quit ModelSim.
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Watch Pane
Watch Pane
The Watch pane shows values for signals and variables at the current simulation time. Unlike the Objects or Locals pane, the Watch pane allows you to view any signal or variable in the design regardless of the current context.
Figure 2-27. .Watch Pane
You can view the following objects in the watch pane.
•
VHDL objects — signals, aliases, generics, constants, and variables
•
Verilog objects — nets, registers, variables, named events, and module parameters
•
Virtual objects — virtual signals and virtual functions
Adding Objects to the Pane
To add objects to the Watch pane, drag-and-drop objects from the Structure tab, Objects pane, or Locals pane. Alternatively, use the add watch command.
Expanding Objects to Show Individual Bits
If you add an array or record to the Watch pane, you can view individual bit values by doubleclicking the array or record. As shown in the graphic above, /ram_tb/dpram1/inaddr has been expanded to show all the individual bit values. Notice the arrow that "ties" the array to the individual bit display.
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Grouping and Ungrouping Objects
You can group objects in the Watch pane so they display and move together. Select the objects, then right click one of the objects and choose Group.
In the graphic below, two different sets of objects have been grouped together.
Figure 2-28. Grouping Objects in the Watch Pane
To ungroup them, right-click the group and select Ungroup.
Saving and Reloading Format Files
You can save a format file (a DO file, actually) that will redraw the contents of the Watch window. Right-click anywhere in the window and select Save Format.
Once you have saved the file, you can reload it by right-clicking and selecting Load Format.
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Wave Window
Wave Window
The Wave window, like the List window, allows you to view the results of your simulation. In the Wave window, however, you can see the results as waveforms and their values.
The Wave window opens by default in the MDI frame of the Main window as shown below.
The window can be undocked from the main window by clicking the Undock button in the window header or by using the view -undock wave command. The preference variable
PrefMain(ViewUnDocked) wave can be used to control this default behavior. Setting this variable will open the Wave Window undocked each time you start ModelSim.
Figure 2-29. Wave Window Undock Button
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Here is an example of a Wave window that is undocked from the MDI frame. All menus and icons associated with Wave window functions now appear in the menu and toolbar areas of the
Wave window.
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Figure 2-30. Wave Window Dock Button
Simulator Windows
Wave Window
If the Wave window is docked into the Main window MDI frame, all menus and icons that were in the standalone version of the Wave window move into the Main window menu bar and toolbar.
The Wave window is divided into a number of window panes. All window panes in the Wave window can be resized by clicking and dragging the bar between any two panes.
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Example 2-1. Wave Window Panes
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The following types of objects can be viewed in the Wave window
•
VHDL objects (indicated by a dark blue diamond) — signals, aliases, process variables, and shared variables
•
Verilog objects (indicated by a light blue diamond) — nets, registers, variables, and named events
•
Virtual objects (indicated by an orange diamond) — virtual signals, buses, and functions, see;
Virtual Objects for more information
The data in the object values pane is very similar to the Objects window, except that the values change dynamically whenever a cursor in the waveform pane is moved.
At the bottom of the waveform pane you can see a time line, tick marks, and the time value of each cursor’s position. As you click and drag to move a cursor, the time value at the cursor location is updated at the bottom of the cursor.
You can resize the window panes by clicking on the bar between them and dragging the bar to a new location.
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Waveform and signal-name formatting are easily changed via the Format menu. You can reuse any formatting changes you make by saving a Wave window format file (see
Wave Window Panes
The sections below describe the various Wave window panes.
Pathname Pane
The pathname pane displays signal pathnames. Signals can be displayed with full pathnames, as shown here, or with only the leaf element displayed. You can increase the size of the pane by clicking and dragging on the right border. The selected signal is highlighted.
The white bar along the left margin indicates the selected dataset (see
Value Pane
The value pane displays the values of the displayed signals.
The radix for each signal can be symbolic, binary, octal, decimal, unsigned, hexadecimal,
ASCII, or default. The default radix can be set by selecting Simulate > Runtime Options.
Note
When the symbolic radix is chosen for SystemVerilog reg and integer types, the values are treated as binary. When the symbolic radix is chosen for SystemVerilog bit and int types, the values are considered to be decimal.
The data in this pane is similar to that shown in the
Objects Pane , except that the values change
dynamically whenever a cursor in the waveform pane is moved.
Waveform Pane
The waveform pane displays the waveforms that correspond to the displayed signal pathnames.
It also displays up to 20 cursors. Signal values can be displayed in analog step, analog interpolated, analog backstep, literal, logic, and event formats. The radix of each signal can be set individually by selecting the signal and then choosing . The default radix is logic.
If you rest your mouse pointer on a signal in the waveform pane, a popup displays with information about the signal. You can toggle this popup on and off in the Wave Window
Properties dialog.
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Cursor Panes
There are three cursor panes–the left pane shows the cursor names; the middle pane shows the current simulation time and the value for each cursor; and the right pane shows the absolute time value for each cursor and relative time between cursors. Up to 20 cursors can be displayed.
See
Measuring Time with Cursors in the Wave Window for more information.
Wave Window Toolbar
The Wave window toolbar (in the undocked Wave window) gives you quick access to these
ModelSim commands and functions.
Button
Table 2-10. Wave Window Toolbar Buttons and Menu Selections
Menu equivalent Other options
File > Open
Open Dataset
open a previously saved dataset
Save Format
save the current Wave window display and signal preferences to a DO (macro) file
File > Save
File > Open from Main window when Transcript window sim tab is active none
print a user-selected range of the current Wave window display to a printer or a file
Export Waveform
export a created waveform
File > Print
File > Print Postscript
File > Export >
Waveform none none
Cut
cut the selected signal from the
Wave window
Copy
copy the signal selected in the pathname pane
Paste
paste the copied signal above another selected signal
Find
find a name or value in the
Wave window
Edit > Cut
Edit > Copy
Edit > Paste
Edit > Find right mouse in pathname pane
> Cut right mouse in pathname pane
> Copy right mouse in pathname pane
> Paste
<control-f> Windows
<control-s> UNIX
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Button
Table 2-10. Wave Window Toolbar Buttons and Menu Selections
Menu equivalent Other options
Insert Cursor
add a cursor to the waveform pane
Add > Wave > Cursor
(Main window)
Add > Cursor
(undocked Wave window) right click in cursor pane and select New Cursor
Edit > Delete Cursor right mouse in cursor pane >
Delete Cursor n
Delete Cursor
delete the selected cursor from the window
Find Previous Transition
locate the previous signal value change for the selected signal
Edit > Search
(Search Reverse) keyboard: Shift + Tab
Edit > Search
(Search Forward) keyboard: Tab
Find Next Transition
locate the next signal value change for the selected signal
Select Mode
set mouse to Select Mode – click left mouse button to select, drag middle mouse button to zoom
Zoom Mode
set mouse to Zoom Mode – drag left mouse button to zoom, click middle mouse button to select
Zoom In 2x
zoom in by a factor of two from the current view
Zoom Out 2x
zoom out by a factor of two from current view
Zoom in on Active Cursor
center active cursor in the display and zoom in
Zoom Full
zoom out to view the full range of the simulation from time 0 to the current time
View > Zoom >
Mouse Mode > Select
Mode
View > Zoom >
Mouse Mode > Zoom
Mode
View > Zoom > Zoom
In
View > Zoom > Zoom
Out
View > Zoom > Zoom
Cursor
View > Zoom > Zoom
Full none none keyboard: i I or + right mouse in wave pane >
Zoom In keyboard: o O or right mouse in wave pane >
Zoom Out keyboard: c or C keyboard: f or F right mouse in wave pane >
Zoom Full
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Button
Table 2-10. Wave Window Toolbar Buttons and Menu Selections
Menu equivalent
none
Other options
Stop Wave Drawing
halts any waves currently being drawn in the Wave window
Show Drivers
display driver(s) of the selected signal, net, or register in the Dataflow window
Restart
reloads the design elements and resets the simulation time to zero, with the option of keeping the current formatting, breakpoints, and
WLF file
[Dataflow window]
Navigate > Expand net to drivers
Main menu:
Simulate > Run >
Restart
[Dataflow window] Expand net to all drivers
right mouse in wave pane >
Show Drivers restart <arguments> use the run command at the
VSIM prompt
Run
run the current simulation for the default time length
Continue Run
continue the current simulation run
Run -All
run the current simulation forever, or until it hits a breakpoint or specified break event
Break
stop the current simulation run
Main menu:
Simulate > Run > Run
<default_length>
Main menu:
Simulate > Run >
Continue
Main menu:
Simulate > Run > Run
-All none use the command at the VSIM prompt use the run run
-continue
-all command at the VSIM prompt none
Find First Difference
find the first difference in a waveform comparison
Find Previous Annotated
Difference
find the previous annotated difference in a waveform comparison
Find Previous Difference
find the previous difference in a waveform comparison none none none none none none
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Button
Table 2-10. Wave Window Toolbar Buttons and Menu Selections
Menu equivalent
none
Other options
none
Find Next Difference
find the next difference in a waveform comparison none none
Find Next Annotated
Difference
find the next annotated difference in a waveform comparison
Find Last Difference
find the last difference in a waveform comparison none none
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Chapter 3
Projects
Projects simplify the process of compiling and simulating a design and are a great tool for getting started with ModelSim.
What are Projects?
Projects are collection entities for designs under specification or test. At a minimum, projects have a root directory, a work library, and "metadata" which are stored in a .mpf file located in a project's root directory. The metadata include compiler switch settings, compile order, and file mappings. Projects may also include:
•
Source files or references to source files
• other files such as READMEs or other project documentation
• local libraries
• references to global libraries
•
Simulation Configurations (see
Creating a Simulation Configuration )
•
Folders (see
Organizing Projects with Folders )
Note
Project metadata are updated and stored only for actions taken within the project itself.
For example, if you have a file in a project, and you compile that file from the command line rather than using the project menu commands, the project will not update to reflect any new compile settings.
What are the Benefits of Projects?
Projects offer benefits to both new and advanced users. Projects
• simplify interaction with ModelSim; you don’t need to understand the intricacies of compiler switches and library mappings
• eliminate the need to remember a conceptual model of the design; the compile order is maintained for you in the project. Compile order is maintained for HDL-only designs.
• remove the necessity to re-establish compiler switches and settings at each session; these are stored in the project metadata as are mappings to source files
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• allow users to share libraries without copying files to a local directory; you can establish references to source files that are stored remotely or locally
• allow you to change individual parameters across multiple files; in previous versions you could only set parameters one file at a time
• enable "what-if" analysis; you can copy a project, manipulate the settings, and rerun it to observe the new results
• reload the initial settings from the project .mpf file every time the project is opened
Project Conversion Between Versions
Projects are generally not backwards compatible for either number or letter releases. When you open a project created in an earlier version, you will see a message warning that the project will be converted to the newer version. You have the option of continuing with the conversion or cancelling the operation.
As stated in the warning message, a backup of the original project is created before the conversion occurs. The backup file is named <project name>.mpf.bak and is created in the same directory in which the original project is located.
Getting Started with Projects
This section describes the four basic steps to working with a project.
•
Step 1 — Creating a New Project
This creates a .mpf file and a working library.
•
Step 2 — Adding Items to the Project
Projects can reference or include source files, folders for organization, simulations, and any other files you want to associate with the project. You can copy files into the project directory or simply create mappings to files in other locations.
•
This checks syntax and semantics and creates the pseudo machine code ModelSim uses for simulation.
•
This specifies the design unit you want to simulate and opens a structure tab in the
Workspace pane.
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Step 1 — Creating a New Project
Select File > New > Project to create a new project. This opens the Create Project dialog where you can specify a project name, location, and default library name. You can generally leave the Default Library Name set to "work." The name you specify will be used to create a working library subdirectory within the Project Location. This dialog also allows you to reference library settings from a selected .ini file or copy them directly into the project.
Figure 3-1. Create Project Dialog
After selecting OK, you will see a blank Project tab in the Workspace pane of the Main window
(
Figure 3-2. Project Tab in Workspace Pane
and the Add Items to the Project dialog (
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Figure 3-3. Add items to the Project Dialog
The name of the current project is shown at the bottom left corner of the Main window.
Step 2 — Adding Items to the Project
The Add Items to the Project dialog includes these options:
•
Create New File — Create a new VHDL, Verilog, Tcl, or text file using the Source editor. See below for details.
•
Add Existing File — Add an existing file. See below for details.
•
Create Simulation — Create a Simulation Configuration that specifies source files and simulator options. See
Creating a Simulation Configuration for details.
•
Create New Folder — Create an organization folder. See
Create New File
The File > New > Source menu selections allow you to create a new VHDL, Verilog, Tcl, or text file using the Source editor.
You can also create a new project file by selecting Project > Add to Project > New File (the
Project tab in the Workspace must be active) or right-clicking in the Project tab and selecting
Add to Project > New File. This will open the Create Project File dialog ( Figure 3-4
).
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Figure 3-4. Create Project File Dialog
Specify a name, file type, and folder location for the new file.
When you select OK, the file is listed in the Project tab. Double-click the name of the new file and a Source editor window will open, allowing you to create source code.
Add Existing File
You can add an existing file to the project by selecting Project > Add to Project > Existing
File or by right-clicking in the Project tab and selecting Add to Project > Existing File.
Figure 3-5. Add file to Project Dialog
When you select OK, the file(s) is added to the Project tab.
Step 3 — Compiling the Files
The question marks in the Status column in the Project tab denote either the files haven’t been compiled into the project or the source has changed since the last compile. To compile the files, select Compile > Compile All or right click in the Project tab and select Compile > Compile
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Figure 3-6. Right-click Compile Menu in Project Tab of Workspace
Once compilation is finished, click the Library tab, expand library work by clicking the "+", and you will see the compiled design units.
Figure 3-7. Click Plus Sign to Show Design Hierarchy
Step 4 — Simulating a Design
To simulate a design, do one of the following:
• double-click the Name of an appropriate design object (such as a testbench module or entity) in the Library tab of the Workspace
• right-click the Name of an appropriate design object and select Simulate from the popup menu
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• select Simulate > Start Simulation from the menus to open the Start Simulation dialog
(
Figure 3-8 ). Select a design unit in the Design tab. Set other options in the VHDL,
Verilog, Libraries, SDF, and Others tabs. Then click OK to start the simulation.
Figure 3-8. Start Simulation Dialog
Projects
Getting Started with Projects
A new tab named sim appears that shows the structure of the active simulation ( Figure 3-9 ).
Figure 3-9. Structure Tab of the Workspace
At this point you are ready to run the simulation and analyze your results. You often do this by adding signals to the Wave window and running the simulation for a given period of time. See the ModelSim Tutorial for examples.
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The Project Tab
Other Basic Project Operations
Open an Existing Project
If you previously exited ModelSim with a project open, ModelSim automatically will open that same project upon startup. You can open a different project by selecting File > Open and choosing Project Files from the Files of type drop-down.
Close a Project
Right-click in the Project tab and select Close Project. This closes the Project tab but leaves the
Library tab open in the workspace. Note that you cannot close a project while a simulation is in progress.
The Project Tab
The Project tab contains information about the objects in your project. By default the tab is divided into five columns.
Figure 3-10. Project Displayed in Workspace
88
•
Name – The name of a file or object.
•
Status – Identifies whether a source file has been successfully compiled. Applies only to
VHDL or Verilog files. A question mark means the file hasn’t been compiled or the source file has changed since the last successful compile; an X means the compile failed; a check mark means the compile succeeded; a checkmark with a yellow triangle behind it means the file compiled but there were warnings generated.
•
Type – The file type as determined by registered file types on Windows or the type you specify when you add the file to the project.
•
Order – The order in which the file will be compiled when you execute a Compile All command.
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•
Modified – The date and time of the last modification to the file.
You can hide or show columns by right-clicking on a column title and selecting or deselecting entries.
Sorting the List
You can sort the list by any of the five columns. Click on a column heading to sort by that column; click the heading again to invert the sort order. An arrow in the column heading indicates which field the list is sorted by and whether the sort order is descending (down arrow) or ascending (up arrow).
Changing Compile Order
The Compile Order dialog box is functional for HDL-only designs. When you compile all files in a project, ModelSim by default compiles the files in the order in which they were added to the project. You have two alternatives for changing the default compile order: 1) select and compile each file individually; 2) specify a custom compile order.
To specify a custom compile order, follow these steps:
1. Select Compile > Compile Order or select it from the context menu in the Project tab.
Figure 3-11. Setting Compile Order
2. Drag the files into the correct order or use the up and down arrow buttons. Note that you can select multiple files and drag them simultaneously.
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Changing Compile Order
Auto-Generating Compile Order
Auto Generate is supported for HDL-only designs. The Auto Generate button in the Compile
Order dialog (see above) "determines" the correct compile order by making multiple passes over the files. It starts compiling from the top; if a file fails to compile due to dependencies, it moves that file to the bottom and then recompiles it after compiling the rest of the files. It continues in this manner until all files compile successfully or until a file(s) can’t be compiled for reasons other than dependency.
Files can be displayed in the Project tab in alphabetical or compile order (by clicking the column headings). Keep in mind that the order you see in the Project tab is not necessarily the order in which the files will be compiled.
Grouping Files
You can group two or more files in the Compile Order dialog so they are sent to the compiler at the same time. For example, you might have one file with a bunch of Verilog define statements and a second file that is a Verilog module. You would want to compile these two files together.
To group files, follow these steps:
1. Select the files you want to group.
Figure 3-12. Grouping Files
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2. Click the Group button.
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Creating a Simulation Configuration
To ungroup files, select the group and click the Ungroup button.
Creating a Simulation Configuration
A Simulation Configuration associates a design unit(s) and its simulation options. For example, say you routinely load a particular design and you have to specify the simulator resolution, generics, and SDF timing files. Ordinarily you would have to specify those options each time you load the design. With a Simulation Configuration, you would specify the design and those options and then save the configuration with a name (e.g., top_config). The name is then listed in the Project tab and you can double-click it to load the design along with its options.
To create a Simulation Configuration, follow these steps:
1. Select Project > Add to Project > Simulation Configuration from the main menu, or right-click the Project tab and select Add to Project > Simulation Configuration from the popup context menu in the Project tab.
Figure 3-13. Simulation Configuration Dialog
2. Specify a name in the Simulation Configuration Name field.
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Organizing Projects with Folders
3. Specify the folder in which you want to place the configuration (see
Organizing Projects with Folders
).
4. Select one or more design unit(s). Use the Control and/or Shift keys to select more than one design unit. The design unit names appear in the Simulate field when you select them.
5. Use the other tabs in the dialog to specify any required simulation options.
Click OK and the simulation configuration is added to the Project tab.
Figure 3-14. Simulation Configuration in the Project Tab
Double-click the Simulation Configuration verilog_sim to load the design.
Organizing Projects with Folders
The more files you add to a project, the harder it can be to locate the item you need. You can add "folders" to the project to organize your files. These folders are akin to directories in that you can have multiple levels of folders and sub-folders. However, no actual directories are created via the file system–the folders are present only within the project file.
Adding a Folder
To add a folder to your project, select Project > Add to Project > Folder or right-click in the
Project tab and select Add to Project > Folder ( Figure 3-15 ).
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Figure 3-15. Add Folder Dialog
Specify the Folder Name, the location for the folder, and click OK. The folder will be displayed in the Project tab.
You use the folders when you add new objects to the project. For example, when you add a file, you can select which folder to place it in.
Figure 3-16. Specifying a Project Folder
If you want to move a file into a folder later on, you can do so using the Properties dialog for the file. Simply right-click on the filename in the Project tab and select Properties from the context menu that appears. This will open the Project Compiler Settings Dialog (
Place in Folder field to specify a folder.
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Specifying File Properties and Project Settings
Figure 3-17. Project Compiler Settings Dialog
On Windows platforms, you can also just drag-and-drop a file into a folder.
Specifying File Properties and Project Settings
You can set two types of properties in a project: file properties and project settings. File properties affect individual files; project settings affect the entire project.
File Compilation Properties
The VHDL and Verilog compilers (vcom and vlog, respectively) have numerous options that affect how a design is compiled and subsequently simulated. You can customize the settings on individual files or a group of files.
Note
Any changes you make to the compile properties outside of the project, whether from the command line, the GUI, or the modelsim.ini file, will not affect the properties of files already in the project.
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Specifying File Properties and Project Settings
To customize specific files, select the file(s) in the Project tab, right click on the file names, and select Properties. The resulting Project Compiler Settings dialog (
depending on the number and type of files you have selected. If you select a single VHDL or
Verilog file, you will see the General tab, Coverage tab, and the VHDL or Verilog tab, respectively. On the General tab, you will see file properties such as Type, Location, and Size.
If you select multiple files, the file properties on the General tab are not listed. Finally, if you select both a VHDL file and a Verilog file, you will see all tabs but no file information on the
General tab.
Figure 3-18. Specifying File Properties
When setting options on a group of files, keep in mind the following:
•
If two or more files have different settings for the same option, the checkbox in the dialog will be "grayed out." If you change the option, you cannot change it back to a
"multi- state setting" without cancelling out of the dialog. Once you click OK,
ModelSim will set the option the same for all selected files.
•
If you select a combination of VHDL and Verilog files, the options you set on the
VHDL and Verilog tabs apply only to those file types.
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Project Settings
To modify project settings, right-click anywhere within the Project tab and select Project
Settings.
Figure 3-19. Project Settings Dialog
Converting Pathnames to Softnames for Location Mapping
If you are using location mapping, you can convert a relative pathname, full pathname, or pathname with an environment variable to a softname. A softname is a term for a pathname that uses the location mapping (MGC_LOCATION_MAP). It looks like a pathname containing an environment variable, however it is resolved using the location map rather than the environment.
To convert the pathname to a softname for projects using location mapping, follow these steps:
1. Right-click anywhere within the Project tab and select Project Settings
2. Enable the Convert pathnames to softnames within the Location map area of the dialog (
).
Once enabled, all pathnames currently in the project and any that are added later are then converted to softnames.
During conversion, if there is no softname in the mgc location map matching the entry, the pathname is converted in to a full (hardened) pathname. A pathname is hardened by removing the environment variable or the relative portion of the path. If this happens, any existing
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pathnames that are either relative or use environment variables are also changed: either to softnames if possible, or to hardened pathnames if not.
For more information on location mapping and pathnames, see
Accessing Projects from the Command Line
Generally, projects are used from within the ModelSim GUI. However, standalone tools will use the project file if they are invoked in the project's root directory. If you want to invoke outside the project directory, set the MODELSIM environment variable with the path to the project file (<Project_Root_Dir>/<Project_Name>.mpf).
You can also use the project command from the command line to perform common operations on projects.
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Chapter 4
Design Libraries
VHDL designs are associated with libraries, which are objects that contain compiled design units. Verilog and SystemVerilog designs simulated within ModelSim are compiled into libraries as well.
Design Library Overview
A design library is a directory or archive that serves as a repository for compiled design units.
The design units contained in a design library consist of VHDL entities, packages, architectures, and configurations; Verilog modules and UDPs (user-defined primitives). The design units are classified as follows:
•
Primary design units — Consist of entities, package declarations, configuration declarations, modulesUDPs. Primary design units within a given library must have unique names.
•
Secondary design units — Consist of architecture bodiespackage bodies. Secondary design units are associated with a primary design unit. Architectures by the same name can exist if they are associated with different entities or modules.
Design Unit Information
The information stored for each design unit in a design library is:
• retargetable, executable code
• debugging information
• dependency information
Working Library Versus Resource Libraries
Design libraries can be used in two ways:
1. as a local working library that contains the compiled version of your design;
2. as a resource library.
The contents of your working library will change as you update your design and recompile. A resource library is typically static and serves as a parts source for your design. You can create
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your own resource libraries or they may be supplied by another design team or a third party
(e.g., a silicon vendor).
Only one library can be the working library.
Any number of libraries can be resource libraries during a compilation. You specify which resource libraries will be used when the design is compiled, and there are rules to specify in which order they are searched (refer to
Specifying the Resource Libraries ).
A common example of using both a working library and a resource library is one in which your gate-level design and testbench are compiled into the working library and the design references gate-level models in a separate resource library.
The Library Named "work"
The library named "work" has special attributes within ModelSim — it is predefined in the compiler and need not be declared explicitly (i.e. library work). It is also the library name used by the compiler as the default destination of compiled design units (i.e., it does not need to be mapped). In other words, the work library is the default working library.
Archives
By default, design libraries are stored in a directory structure with a sub-directory for each design unit in the library. Alternatively, you can configure a design library to use archives. In this case, each design unit is stored in its own archive file. To create an archive, use the -archive argument to the vlib command.
Generally you would do this only in the rare case that you hit the reference count limit on Inodes due to the ".." entries in the lower-level directories (the maximum number of subdirectories on UNIX and Linux is 65533). An example of an error message that is produced when this limit is hit is: mkdir: cannot create directory `65534': Too many links
Archives may also have limited value to customers seeking disk space savings.
Note
GMAKE won’t work with these archives on the IBM platform.
Working with Design Libraries
The implementation of a design library is not defined within standard VHDL or Verilog. Within
ModelSim, design libraries are implemented as directories and can have any legal name allowed by the operating system, with one exception: extended identifiers are not supported for library names.
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Creating a Library
When you create a project (refer to
Getting Started with Projects ), ModelSim automatically
creates a working design library. If you don’t create a project, you need to create a working design library before you run the compiler. This can be done from either the command line or from the ModelSim graphic interface.
From the ModelSim prompt or a UNIX/DOS prompt, use this vlib command:
vlib <directory_pathname>
To create a new library with the graphic interface, select File > New > Library.
Figure 4-1. Creating a New Library
When you click OK, ModelSim creates the specified library directory and writes a speciallyformatted file named _info into that directory. The _info file must remain in the directory to distinguish it as a ModelSim library.
The new map entry is written to the modelsim.ini file in the [Library] section. Refer to
Path Variables for more information.
Note
Remember that a design library is a special kind of directory. The only way to create a library is to use the ModelSim GUI or the vlib command. Do not try to create libraries using UNIX, DOS, or Windows commands.
Managing Library Contents
Library contents can be viewed, deleted, recompiled, edited and so on using either the graphic interface or command line.
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The Library tab in the Workspace pane provides access to design units (configurations, modules, packages, entitiesarchitectures) in a library. Various information about the design units is displayed in columns to the right of the design unit name.
Figure 4-2. Design Unit Information in the Workspace
The Library tab has a context menu with various commands that you access by clicking your right mouse button (Windows—2nd button, UNIX—3rd button) in the Library tab.
The context menu includes the following commands:
•
Simulate — Loads the selected design unit and opens structure and Files tabs in the workspace. Related command line command is vsim .
•
Edit — Opens the selected design unit in the Source window; or, if a library is selected, opens the Edit Library Mapping dialog (refer to
).
•
Refresh — Rebuilds the library image of the selected library without using source code.
Related command line command is vcom or vlog with the -refresh argument.
•
Recompile — Recompiles the selected design unit. Related command line command is vcom or vlog .
•
Update — Updates the display of available libraries and design units.
Assigning a Logical Name to a Design Library
VHDL uses logical library names that can be mapped to ModelSim library directories. By default, ModelSim can find libraries in your current directory (assuming they have the right name), but for it to find libraries located elsewhere, you need to map a logical library name to the pathname of the library.
You can use the GUI, a command, or a project to assign a logical name to a design library.
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Library Mappings with the GUI
To associate a logical name with a library, select the library in the workspace, right-click you mouse, and select Edit from the context menu that appears. This brings up a dialog box that allows you to edit the mapping.
Figure 4-3. Edit Library Mapping Dialog
The dialog box includes these options:
•
Library Mapping Name — The logical name of the library.
•
Library Pathname — The pathname to the library.
Library Mapping from the Command Line
You can set the mapping between a logical library name and a directory with the vmap command using the following syntax:
vmap <logical_name> <directory_pathname>
You may invoke this command from either a UNIX/DOS prompt or from the command line within ModelSim.
The vmap command adds the mapping to the library section of the modelsim.ini file. You can also modify modelsim.ini manually by adding a mapping line. To do this, use a text editor and add a line under the [Library] section heading using the syntax:
<logical_name> = <directory_pathname>
More than one logical name can be mapped to a single directory. For example, suppose the
modelsim.ini file in the current working directory contains following lines:
[Library] work = /usr/rick/design my_asic = /usr/rick/design
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This would allow you to use either the logical name work or my_asic in a library or use clause to refer to the same design library.
Unix Symbolic Links
You can also create a UNIX symbolic link to the library using the host platform command:
ln -s <directory_pathname> <logical_name>
The vmap command can also be used to display the mapping of a logical library name to a directory. To do this, enter the shortened form of the command:
vmap <logical_name>
Library Search Rules
The system searches for the mapping of a logical name in the following order:
•
First the system looks for a modelsim.ini file.
•
If the system doesn’t find a modelsim.ini file, or if the specified logical name does not exist in the modelsim.ini file, the system searches the current working directory for a subdirectory that matches the logical name.
An error is generated by the compiler if you specify a logical name that does not resolve to an existing directory.
Moving a Library
Individual design units in a design library cannot be moved. An entire design library can be moved, however, by using standard operating system commands for moving a directory or an archive.
Setting Up Libraries for Group Use
By adding an “others” clause to your modelsim.ini file, you can have a hierarchy of library mappings. If the tool does not find a mapping in the modelsim.ini file, then it will search the
[library] section of the initialization file specified by the “others” clause. For example:
[library] asic_lib = /cae/asic_lib work = my_work others = /usr/modeltech/modelsim.ini
You can specify only one "others" clause in the library section of a given modelsim.ini file.
The others clause only instructs the tool to look in the specified modelsim.ini file for a library, it does not load any other part of the specified file.
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Specifying the Resource Libraries
Verilog Resource Libraries
ModelSim supports separate compilation of distinct portions of a Verilog design. The vlog compiler is used to compile one or more source files into a specified library. The library thus contains pre-compiled modules and UDPs that are referenced by the simulator as it loads the design.
Note
Resource libraries are specified differently for Verilog and VHDL. For Verilog you use either the -L or -Lf argument to vlog . Refer to
Library Usage for more information.
VHDL Resource Libraries
Within a VHDL source file, you use the VHDL library clause to specify logical names of one or more resource libraries to be referenced in the subsequent design unit. The scope of a library clause includes the text region that starts immediately after the library clause and extends to the end of the declarative region of the associated design unit. It does not extend to the next design
unit in the file.
Note that the library clause is not used to specify the working library into which the design unit is placed after compilation. The vcom command adds compiled design units to the current working library. By default, this is the library named work. To change the current working library, you can use vcom -work and specify the name of the desired target library.
Predefined Libraries
Certain resource libraries are predefined in standard VHDL. The library named std contains the packages standard and textio, which should not be modified. The contents of these packages and other aspects of the predefined language environment are documented in the IEEE Standard
VHDL Language Reference Manual, Std 1076. Refer also to,
A VHDL use clause can be specified to select particular declarations in a library or package that are to be visible within a design unit during compilation. A use clause references the compiled version of the package—not the source.
By default, every VHDL design unit is assumed to contain the following declarations:
LIBRARY std, work;
USE std.standard.all
To specify that all declarations in a library or package can be referenced, add the suffix .all to the library/package name. For example, the use clause above specifies that all declarations in the package standard, in the design library named std, are to be visible to the VHDL design unit
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immediately following the use clause. Other libraries or packages are not visible unless they are explicitly specified using a library or use clause.
Another predefined library is work, the library where a design unit is stored after it is compiled as described earlier. There is no limit to the number of libraries that can be referenced, but only one library is modified during compilation.
Alternate IEEE Libraries Supplied
The installation directory may contain two or more versions of the IEEE library:
•
ieeepure — Contains only IEEE approved packages (accelerated for ModelSim).
•
ieee — Contains precompiled Synopsys and IEEE arithmetic packages which have been accelerated by Model Technology including math_complex, math_real, numeric_bit, numeric_std, std_logic_1164, std_logic_misc, std_logic_textio, std_logic_arith, std_logic_signed, std_logic_unsigned, vital_primitives, and vital_timing.
You can select which library to use by changing the mapping in the modelsim.ini file. The
modelsim.ini file in the installation directory defaults to the ieee library.
Regenerating Your Design Libraries
Depending on your current ModelSim version, you may need to regenerate your design libraries before running a simulation. Check the installation README file to see if your libraries require an update. You can regenerate your design libraries using the Refresh command from the
Library tab context menu (refer to
Managing Library Contents ), or by using the -refresh
argument to vcom and
vlog
.
From the command line, you would use vcom with the -refresh argument to update VHDL design units in a library, and vlog with the -refresh argument to update Verilog design units. By default, the work library is updated. Use either vcom or vlog with the -work <library> argument to update a different library. For example, if you have a library named mylib that contains both VHDL and Verilog design units:
vcom -work mylib -refresh vlog -work mylib -refresh
An important feature of -refresh is that it rebuilds the library image without using source code.
This means that models delivered as compiled libraries without source code can be rebuilt for a specific release of ModelSim. In general, this works for moving forwards or backwards on a release. Moving backwards on a release may not work if the models used compiler switches, directives, language constructs, or features that do not exist in the older release.
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Note
You don't need to regenerate the std, ieee, vital22b, and verilog libraries. Also, you cannot use the -refresh option to update libraries that were built before the 4.6 release.
Maintaining 32- and 64-bit Versions in the Same Library
ModelSim allows you to maintain 32-bit and 64-bit versions of a design in the same library.
To do this, you must compile the design with the 32-bit version and then "refresh" the design with the 64-bit version. For example:
Using the 32-bit version of ModelSim:
vlog file1.v file2.v -forcecode -work asic_lib
Next, using the 64-bit version of ModelSim:
vlog -work asic_lib -refresh
This allows you to use either version without having to do a refresh.
Do not compile the design with one version, and then recompile it with the other. If you do this,
ModelSim will remove the first module, because it could be "stale."
Importing FPGA Libraries
ModelSim includes an import wizard for referencing and using vendor FPGA libraries. The wizard scans for and enforces dependencies in the libraries and determines the correct mappings and target directories.
Note
The FPGA libraries you import must be pre-compiled. Most FPGA vendors supply precompiled libraries configured for use with ModelSim.
To import an FPGA library, select File > Import > Library.
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Figure 4-4. Import Library Wizard
Follow the instructions in the wizard to complete the import.
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Chapter 5
VHDL Simulation
This chapter describes how to compile, optimize, and simulate VHDL designs in ModelSim. It also discusses using the TextIO package with ModelSim; ModelSim’s implementation of the
VITAL (VHDL Initiative Towards ASIC Libraries) specification for ASIC modeling; and
ModelSim’s special built-in utilities package.
The TextIO package is defined within the VHDL Language Reference Manual, IEEE Std 1076; it allows human-readable text input from a declared source within a VHDL file during simulation.
Basic VHDL Flow
Simulating VHDL designs with ModelSim includes four general steps:
1. Compile your VHDL code into one or more libraries using the vcom command. See
Compiling VHDL Files for details.
2. Load your design with the vsim command. See
Simulating VHDL Designs for details.
3. Run and debug your design.
Compiling VHDL Files
Creating a Design Library for VHDL
Before you can compile your source files, you must create a library in which to store the compilation results. Use vlib to create a new library. For example:
vlib work
This creates a library named work. By default, compilation results are stored in the work library.
The work library is actually a subdirectory named work. This subdirectory contains a special file named _info. Do not create libraries using UNIX, MS Windows, or DOS commands – always use the vlib command.
See
Design Libraries for additional information on working with libraries.
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Invoking the VHDL Compiler
ModelSim compiles one or more VHDL design units with a single invocation of vcom , the
VHDL compiler. The design units are compiled in the order that they appear on the command line. For VHDL, the order of compilation is important – you must compile any entities or configurations before an architecture that references them.
You can simulate a design containing units written with 1076 -1987, 1076 -1993, and
1076-2002 versions of VHDL. To do so you will need to compile units from each VHDL version separately. The vcom command compiles using 1076 -2002 rules by default; use the -87 or -93 argument to vcom to compile units written with version 1076-1987 or 1076 -1993, respectively. You can also change the default by modifying the VHDL93 variable in the
modelsim.ini file (see
Simulator Control Variables for more information).
Dependency Checking
Dependent design units must be reanalyzed when the design units they depend on are changed in the library.
vcom determines whether or not the compilation results have changed. For example, if you keep an entity and its architectures in the same source file and you modify only an architecture and recompile the source file, the entity compilation results will remain unchanged and you will not have to recompile design units that depend on the entity.
Range and Index Checking
A range check verifies that a scalar value defined with a range subtype is always assigned a value within its range. An index check verifies that whenever an array subscript expression is evaluated, the subscript will be within the array's range.
Range and index checks are performed by default when you compile your design. You can disable range checks (potentially offering a performance advantage) and index checks using arguments to the vcom command. Or, you can use the NoRangeCheck and NoIndexCheck variables in the modelsim.ini file to specify whether or not they are performed. See
Range checks in ModelSim are slightly more restrictive than those specified by the VHDL
LRM. ModelSim requires any assignment to a signal to also be in range whereas the LRM requires only that range checks be done whenever a signal is updated. Most assignments to signals update the signal anyway, and the more restrictive requirement allows ModelSim to generate better error messages.
Subprogram Inlining
ModelSim attempts to inline subprograms at compile time to improve simulation performance.
This happens automatically and should be largely transparent. However, you can disable automatic inlining two ways:
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•
Invoke vcom with the -O0 or -O1 argument
•
Use the mti_inhibit_inline attribute as described below
Single-stepping through a simulation varies slightly depending on whether inlining occurred.
When single-stepping to a subprogram call that has not been inlined, the simulator stops first at the line of the call, and then proceeds to the line of the first executable statement in the called subprogram. If the called subprogram has been inlined, the simulator does not first stop at the subprogram call, but stops immediately at the line of the first executable statement.
mti_inhibit_inline Attribute
You can disable inlining for individual design units (a package, architecture, or entity) or subprograms with the mti_inhibit_inline attribute. Follow these rules to use the attribute:
•
Declare the attribute within the design unit's scope as follows: attribute mti_inhibit_inline : boolean;
•
Assign the value true to the attribute for the appropriate scope. For example, to inhibit inlining for a particular function (e.g., "foo"), add the following attribute assignment: attribute mti_inhibit_inline of foo : procedure is true;
To inhibit inlining for a particular package (e.g., "pack"), add the following attribute assignment: attribute mti_inhibit_inline of pack : package is true;
Do similarly for entities and architectures.
Differences Between Language Versions
There are three versions of the IEEE VHDL 1076 standard: VHDL-1987, VHDL-1993, and
VHDL-2002. The default language version for ModelSim is VHDL-2002. If your code was written according to the ’87 or ’93 version, you may need to update your code or instruct
ModelSim to use the earlier versions’ rules.
To select a specific language version, do one of the following:
•
Select the appropriate version from the compiler options menu in the GUI
•
Invoke vcom using the argument -87, -93, or -2002
•
Set the VHDL93 variable in the [vcom] section of the modelsim.ini file. Appropriate values for VHDL93 are:
- 0, 87, or 1987 for VHDL-1987
- 1, 93, or 1993 for VHDL-1993
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- 2, 02, or 2002 for VHDL-2002
The following is a list of language incompatibilities that may cause problems when compiling a design.
•
VHDL-93 and VHDL-2002 — The only major problem between VHDL-93 and VHDL-
2002 is the addition of the keyword "PROTECTED". VHDL-93 programs which use this as an identifier should choose a different name.
All other incompatibilities are between VHDL-87 and VHDL-93.
•
VITAL and SDF — It is important to use the correct language version for VITAL.
VITAL2000 must be compiled with VHDL-93 or VHDL-2002. VITAL95 must be compiled with VHDL-87. A typical error message that indicates the need to compile under language version VHDL-87 is:
"VITALPathDelay DefaultDelay parameter must be locally static"
•
Purity of NOW — In VHDL-93 the function "now" is impure. Consequently, any function that invokes "now" must also be declared to be impure. Such calls to "now" occur in VITAL. A typical error message:
"Cannot call impure function 'now' from inside pure function
'<name>'"
•
Files — File syntax and usage changed between VHDL-87 and VHDL-93. In many cases vcom issues a warning and continues:
"Using 1076-1987 syntax for file declaration."
In addition, when files are passed as parameters, the following warning message is produced:
"Subprogram parameter name is declared using VHDL 1987 syntax."
This message often involves calls to endfile(<name>) where <name> is a file parameter.
•
Files and packages — Each package header and body should be compiled with the same language version. Common problems in this area involve files as parameters and the size of type CHARACTER. For example, consider a package header and body with a procedure that has a file parameter: procedure proc1 ( out_file : out std.textio.text) ...
If you compile the package header with VHDL-87 and the body with VHDL-93 or
VHDL-2002, you will get an error message such as:
"** Error: mixed_package_b.vhd(4): Parameter kinds do not conform between declarations in package header and body: 'out_file'."
•
Direction of concatenation — To solve some technical problems, the rules for direction and bounds of concatenation were changed from VHDL-87 to VHDL-93. You won't see any difference in simple variable/signal assignments such as:
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v1 := a & b;
But if you (1) have a function that takes an unconstrained array as a parameter, (2) pass a concatenation expression as a formal argument to this parameter, and (3) the body of the function makes assumptions about the direction or bounds of the parameter, then you will get unexpected results. This may be a problem in environments that assume all arrays have "downto" direction.
• xnor — "xnor" is a reserved word in VHDL-93. If you declare an xnor function in
VHDL-87 (without quotes) and compile it under VHDL-2002, you will get an error message like the following:
** Error: xnor.vhd(3): near "xnor": expecting: STRING IDENTIFIER
•
'FOREIGN attribute — In VHDL-93 package STANDARD declares an attribute
'FOREIGN. If you declare your own attribute with that name in another package, then
ModelSim issues a warning such as the following:
-- Compiling package foopack
** Warning: foreign.vhd(9): (vcom-1140) VHDL-1993 added a definition of the attribute foreign to package std.standard. The attribute is also defined in package 'standard'. Using the definition from package 'standard'.
•
Size of CHARACTER type — In VHDL-87 type CHARACTER has 128 values; in
VHDL-93 it has 256 values. Code which depends on this size will behave incorrectly.
This situation occurs most commonly in test suites that check VHDL functionality. It's unlikely to occur in practical designs. A typical instance is the replacement of warning message:
"range nul downto del is null" by
"range nul downto 'ÿ' is null" -- range is nul downto y(umlaut)
• bit string literals — In VHDL-87 bit string literals are of type bit_vector. In VHDL-93 they can also be of type STRING or STD_LOGIC_VECTOR. This implies that some expressions that are unambiguous in VHDL-87 now become ambiguous is VHDL-93. A typical error message is:
** Error: bit_string_literal.vhd(5): Subprogram '=' is ambiguous.
Suitable definitions exist in packages 'std_logic_1164' and
'standard'.
•
Sub-element association — In VHDL-87 when using individual sub-element association in an association list, associating individual sub-elements with NULL is discouraged. In
VHDL-93 such association is forbidden. A typical message is:
"Formal '<name>' must not be associated with OPEN when subelements are associated individually."
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Simulating VHDL Designs
A VHDL design is ready for simulation after it has been compiled with vcom . The simulator may then be invoked with the name of the configuration or entity/architecture pair.
Note
This section discusses simulation from the UNIX or Windows/DOS command line. You can also use a project to simulate (see
Getting Started with Projects ) or the Simulate
dialog box.
This example invokes vsim on the entity my_asic and the architecture structure:
vsim my_asic structure
vsim is capable of annotating a design using VITAL compliant models with timing data from an
SDF file. You can specify the min:typ:max delay by invoking vsim with the -sdfmin, -sdftyp, or -sdfmax option. Using the SDF file f1.sdf in the current work directory, the following invocation of vsim annotates maximum timing values for the design unit my_asic:
vsim -sdfmax /my_asic=f1.sdf my_asic
By default, the timing checks within VITAL models are enabled. They can be disabled with the
+notimingchecks option. For example:
vsim +notimingchecks topmod
Simulator Resolution Limit (VHDL)
The simulator internally represents time as a 64-bit integer in units equivalent to the smallest unit of simulation time, also known as the simulator resolution limit. The default resolution limit is set to the value specified by the
variable in the modelsim.ini file. You can view the current resolution by invoking the report command with the simulator state option.
Overriding the Resolution
You can override ModelSim’s default resolution by specifying the -t option on the command line or by selecting a different Simulator Resolution in the Simulate dialog box. Available resolutions are: 1x, 10x, or 100x of fs, ps, ns, us, ms, or sec.
For example this command chooses 10 ps resolution:
vsim -t 10ps topmod
Clearly you need to be careful when doing this type of operation. If the resolution set by -t is larger than a delay value in your design, the delay values in that design unit are rounded to the closest multiple of the resolution. In the example above, a delay of 4 ps would be rounded to 0 ps.
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Choosing the Resolution for VHDL
You should choose the coarsest resolution limit possible that does not result in undesired rounding of your delays. The time precision should not be unnecessarily small because it will limit the maximum simulation time limit, and it will degrade performance in some cases.
Default Binding
By default ModelSim performs default binding when you load the design with vsim . The advantage of performing default binding at load time is that it provides more flexibility for compile order. Namely, entities don't necessarily have to be compiled before other entities/architectures which instantiate them.
However, you can force ModelSim to perform default binding at compile time. This may allow you to catch design errors (e.g., entities with incorrect port lists) earlier in the flow. Use one of these two methods to change when default binding occurs:
•
Specify the -bindAtCompile argument to vcom
•
Set the
BindAtCompile variable in the modelsim.ini to 1 (true)
Default Binding Rules
When looking for an entity to bind with, ModelSim searches the currently visible libraries for an entity with the same name as the component. ModelSim does this because IEEE 1076-1987 contained a flaw that made it almost impossible for an entity to be directly visible if it had the same name as the component. In short, if a component was declared in an architecture, any likenamed entity above that declaration would be hidden because component/entity names cannot be overloaded. As a result we implemented the following rules for determining default binding:
•
If performing default binding at load time, search the libraries specified with the -Lf argument to vsim.
•
If a directly visible entity has the same name as the component, use it.
•
If an entity would be directly visible in the absence of the component declaration, use it.
•
If the component is declared in a package, search the library that contained the package for an entity with the same name.
If none of these methods is successful, ModelSim will also do the following:
•
Search the work library.
•
Search all other libraries that are currently visible by means of the library clause.
•
If performing default binding at load time, search the libraries specified with the -L argument to vsim.
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Note that these last three searches are an extension to the 1076 standard.
Disabling Default Binding
If you want default binding to occur only via configurations, you can disable ModelSim’s normal default binding methods by setting the
RequireConfigForAllDefaultBinding
variable in the modelsim.ini to 1 (true).
Delta Delays
Event-based simulators such as ModelSim may process many events at a given simulation time.
Multiple signals may need updating, statements that are sensitive to these signals must be executed, and any new events that result from these statements must then be queued and executed as well. The steps taken to evaluate the design without advancing simulation time are referred to as "delta times" or just "deltas."
The diagram below represents the process for VHDL designs. This process continues until the end of simulation time.
Figure 5-1. VHDL Delta Delay Process
Execute concurrent statements at current time
Advance delta time
Advance simulation time
No
Any transactions to process?
Yes
Any events to process?
Yes
Execute concurrent statements that are sensitive to events
No
This mechanism in event-based simulators may cause unexpected results. Consider the following code snippet:
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clk2 <= clk; process (rst, clk)
begin
if(rst = '0')then
s0 <= '0';
elsif(clk'event and clk='1') then
s0 <= inp; end if;
end process; process (rst, clk2)
begin
if(rst = '0')then
s1 <= '0';
elsif(clk2'event and clk2='1') then
s1 <= s0;
end if;
end process;
In this example you have two synchronous processes, one triggered with clk and the other with
clk2. To your surprise, the signals change in the clk2 process on the same edge as they are set in the clk process. As a result, the value of inp appears at s1 rather than s0.
During simulation an event on clk occurs (from the testbench). From this event ModelSim performs the "clk2 <= clk" assignment and the process which is sensitive to clk. Before advancing the simulation time, ModelSim finds that the process sensitive to clk2 can also be run. Since there are no delays present, the effect is that the value of inp appears at s1 in the same simulation cycle.
In order to get the expected results, you must do one of the following:
•
Insert a delay at every output
•
Make certain to use the same clock
•
Insert a delta delay
To insert a delta delay, you would modify the code like this:
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process (rst, clk)
begin
if(rst = '0')then
s0 <= '0';
elsif(clk'event and clk='1') then
s0 <= inp;
s0_delayed <= s0;
end if;
end process;
process (rst, clk2)
begin
if(rst = '0')then
s1 <= '0';
elsif(clk2'event and clk2='1') then
s1 <= s0_delayed;
end if;
end process;
The best way to debug delta delay problems is observe your signals in the List window. There you can see how values change at each delta time.
Detecting Infinite Zero-Delay Loops
If a large number of deltas occur without advancing time, it is usually a symptom of an infinite zero-delay loop in the design. In order to detect the presence of these loops, ModelSim defines a limit, the “iteration limit", on the number of successive deltas that can occur. When ModelSim reaches the iteration limit, it issues a warning message.
The iteration limit default value is 1000. If you receive an iteration limit warning, first increase the iteration limit and try to continue simulation. You can set the iteration limit from the
Simulate > Runtime Options menu or by modifying the
variable in the
modelsim.ini. See
Simulator Control Variables for more information on modifying the
modelsim.ini file.
If the problem persists, look for zero-delay loops. Run the simulation and look at the source code when the error occurs. Use the step button to step through the code and see which signals or variables are continuously oscillating. Two common causes are a loop that has no exit, or a series of gates with zero delay where the outputs are connected back to the inputs.
Using the TextIO Package
To access the routines in TextIO, include the following statement in your VHDL source code:
USE std.textio.all;
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Using the TextIO Package
A simple example using the package TextIO is:
USE std.textio.all;
ENTITY simple_textio IS
END;
ARCHITECTURE simple_behavior OF simple_textio IS
BEGIN
PROCESS
VARIABLE i: INTEGER:= 42;
VARIABLE LLL: LINE;
BEGIN
WRITE (LLL, i);
WRITELINE (OUTPUT, LLL);
WAIT;
END PROCESS;
END simple_behavior;
Syntax for File Declaration
The VHDL’87 syntax for a file declaration is:
file identifier : subtype_indication is [ mode ] file_logical_name ; where "file_logical_name" must be a string expression.
In newer versions of the 1076 spec, syntax for a file declaration is:
file identifier_list : subtype_indication [ file_open_information ] ; where "file_open_information" is:
[open file_open_kind_expression] is file_logical_name
You can specify a full or relative path as the file_logical_name; for example (VHDL’87):
Normally if a file is declared within an architecture, process, or package, the file is opened when you start the simulator and is closed when you exit from it. If a file is declared in a subprogram, the file is opened when the subprogram is called and closed when execution RETURNs from the subprogram. Alternatively, the opening of files can be delayed until the first read or write by setting the DelayFileOpen variable in the modelsim.ini file. Also, the number of concurrently open files can be controlled by the ConcurrentFileLimit variable. These variables help you manage a large number of files during simulation. See
Simulator Variables for more details.
Using STD_INPUT and STD_OUTPUT Within the Tool
The standard VHDL’87 TextIO package contains the following file declarations:
file input: TEXT is in "STD_INPUT";
file output: TEXT is out "STD_OUTPUT";
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Updated versions of the TextIO package contain these file declarations:
file input: TEXT open read_mode is "STD_INPUT";
file output: TEXT open write_mode is "STD_OUTPUT";
STD_INPUT is a file_logical_name that refers to characters that are entered interactively from the keyboard, and STD_OUTPUT refers to text that is displayed on the screen.
In ModelSim, reading from the STD_INPUT file allows you to enter text into the current buffer from a prompt in the Transcript pane. The lines written to the STD_OUTPUT file appear in the
Transcript.
TextIO Implementation Issues
Writing Strings and Aggregates
A common error in VHDL source code occurs when a call to a WRITE procedure does not specify whether the argument is of type STRING or BIT_VECTOR. For example, the VHDL procedure:
WRITE (L, "hello"); will cause the following error:
ERROR: Subprogram "WRITE" is ambiguous.
In the TextIO package, the WRITE procedure is overloaded for the types STRING and
BIT_VECTOR. These lines are reproduced here: procedure WRITE(L: inout LINE; VALUE: in BIT_VECTOR;
JUSTIFIED: in SIDE:= RIGHT; FIELD: in WIDTH := 0); procedure WRITE(L: inout LINE; VALUE: in STRING;
JUSTIFIED: in SIDE:= RIGHT; FIELD: in WIDTH := 0);
The error occurs because the argument "hello" could be interpreted as a string or a bit vector, but the compiler is not allowed to determine the argument type until it knows which function is being called.
The following procedure call also generates an error:
WRITE (L, "010101");
This call is even more ambiguous, because the compiler could not determine, even if allowed to, whether the argument "010101" should be interpreted as a string or a bit vector.
There are two possible solutions to this problem:
•
Use a qualified expression to specify the type, as in:
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WRITE (L, string’("hello"));
•
Call a procedure that is not overloaded, as in:
WRITE_STRING (L, "hello");
The WRITE_STRING procedure simply defines the value to be a STRING and calls the
WRITE procedure, but it serves as a shell around the WRITE procedure that solves the overloading problem. For further details, refer to the WRITE_STRING procedure in the io_utils package, which is located in the file <install_dir>/modeltech/examples/misc/io_utils.vhd.
Reading and Writing Hexadecimal Numbers
The reading and writing of hexadecimal numbers is not specified in standard VHDL. The Issues
Screening and Analysis Committee of the VHDL Analysis and Standardization Group (ISAC-
VASG) has specified that the TextIO package reads and writes only decimal numbers.
To expand this functionality, ModelSim supplies hexadecimal routines in the package io_utils, which is located in the file <install_dir>/modeltech/examples/misc/io_utils.vhd. To use these routines, compile the io_utils package and then include the following use clauses in your VHDL source code: use std.textio.all; use work.io_utils.all;
Dangling Pointers
Dangling pointers are easily created when using the TextIO package, because WRITELINE deallocates the access type (pointer) that is passed to it. Following are examples of good and bad
VHDL coding styles:
Bad VHDL (because L1 and L2 both point to the same buffer):
READLINE (infile, L1);
L2 := L1;
-- Read and allocate buffer
-- Copy pointers
WRITELINE (outfile, L1); -- Deallocate buffer
Good VHDL (because L1 and L2 point to different buffers):
READLINE (infile, L1); -- Read and allocate buffer
L2 := new string’(L1.all); -- Copy contents
WRITELINE (outfile, L1); -- Deallocate buffer
The ENDLINE Function
The ENDLINE function described in the IEEE Standard VHDL Language Reference Manual,
IEEE Std 1076-1987 contains invalid VHDL syntax and cannot be implemented in VHDL. This
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is because access values must be passed as variables, but functions do not allow variable parameters.
Based on an ISAC-VASG recommendation the ENDLINE function has been removed from the
TextIO package. The following test may be substituted for this function:
(L = NULL) OR (L’LENGTH = 0)
The ENDFILE Function
In the VHDL Language Reference Manuals, the ENDFILE function is listed as:
-- function ENDFILE (L: in TEXT) return BOOLEAN;
As you can see, this function is commented out of the standard TextIO package. This is because the ENDFILE function is implicitly declared, so it can be used with files of any type, not just files of type TEXT.
Using Alternative Input/Output Files
You can use the TextIO package to read and write to your own files. To do this, just declare an input or output file of type TEXT. For example, for an input file:
The VHDL’87 declaration is:
file myinput : TEXT is in "pathname.dat";
The VHDL’93 declaration is:
file myinput : TEXT open read_mode is "pathname.dat";
Then include the identifier for this file ("myinput" in this example) in the READLINE or
WRITELINE procedure call.
Flushing the TEXTIO Buffer
Flushing of the TEXTIO buffer is controlled by the
UnbufferedOutput variable in the
modelsim.ini file.
Providing Stimulus
You can stimulate and test a design by reading vectors from a file, using them to drive values onto signals, and testing the results. A VHDL test bench has been included with the ModelSim install files as an example. Check for this file:
<install_dir>/modeltech/examples/misc/stimulus.vhd
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VITAL Specification and Source Code
VITAL Specification and Source Code
VITAL ASIC Modeling Specification
The IEEE 1076.4 VITAL ASIC Modeling Specification is available from the Institute of
Electrical and Electronics Engineers, Inc.:
IEEE Customer Service
445 Hoes Lane
Piscataway, NJ 08854-1331
Tel: (732) 981-0060
Fax: (732) 981-1721 home page: http://www.ieee.org
VITAL source code
The source code for VITAL packages is provided in the directories:
/<install_dir>/vhdl_src/vital22b
/vital95
/vital2000
VITAL Packages
VITAL 1995 accelerated packages are pre-compiled into the ieee library in the installation directory. VITAL 2000 accelerated packages are pre-compiled into the vital2000 library. If you need to use the newer library, you either need to change the ieee library mapping or add a use clause to your VHDL code to access the VITAL 2000 packages.
To change the ieee library mapping, issue the following command: vmap ieee <modeltech>/vital2000
Or, alternatively, add use clauses to your code:
LIBRARY vital2000;
USE vital2000.vital_primitives.all;
USE vital2000.vital_timing.all;
USE vital2000.vital_memory.all;
Note that if your design uses two libraries -one that depends on vital95 and one that depends on vital2000 - then you will have to change the references in the source code to vital2000.
Changing the library mapping will not work.
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VITAL Compliance
A simulator is VITAL compliant if it implements the SDF mapping and if it correctly simulates designs using the VITAL packages, as outlined in the VITAL Model Development
Specification. ModelSim is compliant with the IEEE 1076.4 VITAL ASIC Modeling
Specification. In addition, ModelSim accelerates the VITAL_Timing, VITAL_Primitives, and
VITAL_memory packages. The optimized procedures are functionally equivalent to the IEEE
1076.4 VITAL ASIC Modeling Specification (VITAL 1995 and 2000).
VITAL Compliance Checking
If you are using VITAL 2.2b, you must turn off the compliance checking either by not setting the attributes, or by invoking vcom with the option -novitalcheck.
Compiling and Simulating with Accelerated
VITAL Packages
vcom automatically recognizes that a VITAL function is being referenced from the ieee library and generates code to call the optimized built-in routines.
Invoke with the -novital option if you do not want to use the built-in VITAL routines (when debugging for instance). To exclude all VITAL functions, use -novital all:
vcom -novital all design.vhd
To exclude selected VITAL functions, use one or more -novital <fname> options:
vcom -novital VitalTimingCheck -novital VitalAND design.vhd
The -novital switch only affects calls to VITAL functions from the design units currently being compiled. Pre-compiled design units referenced from the current design units will still call the built-in functions unless they too are compiled with the -novital option.
ModelSim VITAL built-ins will be updated in step with new releases of the VITAL packages.
Util Package
The util package serves as a container for various VHDL utilities. The package is part of the modelsim_lib library which is located in the modeltech tree and is mapped in the default
modelsim.ini file.
To access the utilities in the package, you would add lines like the following to your VHDL code: library modelsim_lib; use modelsim_lib.util.all;
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Util Package
get_resolution
get_resolution returns the current simulator resolution as a real number. For example, 1 femtosecond corresponds to 1e-15.
Syntax resval := get_resolution;
Returns
Name
resval
Type
real
Description
The simulator resolution represented as a real
Arguments
None
Related functions
•
•
Example
If the simulator resolution is set to 10ps, and you invoke the command:
resval := get_resolution;
the value returned to resval would be 1e-11.
init_signal_driver()
The init_signal_driver() procedure drives the value of a VHDL signal or Verilog net onto an existing VHDL signal or Verilog net. This allows you to drive signals or nets at any level of the design hierarchy from within a VHDL architecture (e.g., a testbench).
See
init_signal_driver for complete details.
init_signal_spy()
The init_signal_spy() utility mirrors the value of a VHDL signal or Verilog register/net onto an existing VHDL signal or Verilog register. This allows you to reference signals, registers, or nets at any level of hierarchy from within a VHDL architecture (e.g., a testbench).
See
init_signal_spy for complete details.
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Util Package
signal_force()
The signal_force() procedure forces the value specified onto an existing VHDL signal or
Verilog register or net. This allows you to force signals, registers, or nets at any level of the design hierarchy from within a VHDL architecture (e.g., a testbench). A signal_force works the same as the force command with the exception that you cannot issue a repeating force.
See
signal_force for complete details.
signal_release()
The signal_release() procedure releases any force that was applied to an existing VHDL signal or Verilog register or net. This allows you to release signals, registers, or nets at any level of the design hierarchy from within a VHDL architecture (e.g., a testbench). A signal_release works the same as the noforce command.
See
signal_release for complete details.
to_real()
to_real() converts the physical type time value into a real value with respect to the current simulator resolution. The precision of the converted value is determined by the simulator resolution. For example, if you were converting 1900 fs to a real and the simulator resolution was ps, then the real value would be 2.0 (i.e., 2 ps).
Syntax realval := to_real(timeval);
Returns
Name
realval
Type
real
Description
The time value represented as a real with respect to the simulator resolution
Arguments
Name
timeval
Type
time
Description
The value of the physical type time
Related functions
•
•
Example
If the simulator resolution is set to ps, and you enter the following function:
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Util Package realval := to_real(12.99 ns);
then the value returned to realval would be 12990.0. If you wanted the returned value to be in units of nanoseconds (ns) instead, you would use the
get_resolution function to recalculate the
value:
realval := 1e+9 * (to_real(12.99 ns)) * get_resolution();
If you wanted the returned value to be in units of femtoseconds (fs), you would enter the function this way:
realval := 1e+15 * (to_real(12.99 ns)) * get_resolution();
to_time()
to_time() converts a real value into a time value with respect to the current simulator resolution.
The precision of the converted value is determined by the simulator resolution. For example, if you were converting 5.9 to a time and the simulator resolution was ps, then the time value would be 6 ps.
Syntax timeval := to_time(realval);
Returns
Name
timeval
Type
time
Description
The real value represented as a physical type time with respect to the simulator resolution
Arguments
Name
realval
Type
real
Description
The value of the type real
Related functions
•
•
Example
If the simulator resolution is set to ps, and you enter the following function:
timeval := to_time(72.49);
then the value returned to timeval would be 72 ps.
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Modeling Memory
As a VHDL user, you might be tempted to model a memory using signals. Two common simulator problems are the likely result:
•
You may get a "memory allocation error" message, which typically means the simulator ran out of memory and failed to allocate enough storage.
•
Or, you may get very long load, elaboration, or run times.
These problems are usually explained by the fact that signals consume a substantial amount of memory (many dozens of bytes per bit), all of which needs to be loaded or initialized before your simulation starts.
Modeling memory with variables or protected types instead provides some excellent performance benefits:
• storage required to model the memory can be reduced by 1-2 orders of magnitude
• startup and run times are reduced
• associated memory allocation errors are eliminated
In the VHDL example below, we illustrate three alternative architectures for entity memory:
•
Architecture bad_style_87 uses a vhdl signal to store the ram data.
•
Architecture style_87 uses variables in the memory process
•
Architecture style_93 uses variables in the architecture.
For large memories, architecture bad_style_87 runs many times longer than the other two, and uses much more memory. This style should be avoided.
Architectures style_87 and style_93 work with equal efficiently. However, VHDL 1993 offers additional flexibility because the ram storage can be shared between multiple processes. For example, a second process is shown that initializes the memory; you could add other processes to create a multi-ported memory.
To implement this model, you will need functions that convert vectors to integers. To use it you will probably need to convert integers to vectors.
Example functions are provided below in package "conversions".
For completeness sake we also show an example using VHDL 2002 protected types, though in this example, protected types offer no advantage over shared variables.
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VHDL87 and VHDL93 Example
library ieee; use ieee.std_logic_1164.all; use work.conversions.all; entity memory is generic(add_bits : integer := 12; data_bits : integer := 32); port(add_in : in std_ulogic_vector(add_bits-1 downto 0); data_in : in std_ulogic_vector(data_bits-1 downto 0); data_out : out std_ulogic_vector(data_bits-1 downto 0); cs, mwrite : in std_ulogic; do_init : in std_ulogic); subtype word is std_ulogic_vector(data_bits-1 downto 0); constant nwords : integer := 2 ** add_bits; end; type ram_type is array(0 to nwords-1) of word; architecture style_93 of memory is
-----------------------------shared variable ram : ram_type;
-----------------------------begin memory: process (cs) variable address : natural; begin if rising_edge(cs) then address := sulv_to_natural(add_in); if (mwrite = '1') then ram(address) := data_in; end if; data_out <= ram(address); end if; end process memory;
-- illustrates a second process using the shared variable initialize: process (do_init) variable address : natural; begin if rising_edge(do_init) then for address in 0 to nwords-1 loop ram(address) := data_in; end loop; end if; end process initialize; end architecture style_93; architecture style_87 of memory is begin memory: process (cs)
----------------------variable ram : ram_type;
----------------------variable address : natural;
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begin if rising_edge(cs) then address := sulv_to_natural(add_in); if (mwrite = '1') then ram(address) := data_in; end if; data_out <= ram(address); end if; end process; end style_87; architecture bad_style_87 of memory is
---------------------signal ram : ram_type;
---------------------begin memory: process (cs) variable address : natural := 0; begin if rising_edge(cs) then address := sulv_to_natural(add_in); if (mwrite = '1') then ram(address) <= data_in; else data_out <= data_in; data_out <= ram(address); end if; end if; end process; end bad_style_87;
------------------------------------------------------------
-----------------------------------------------------------library ieee; use ieee.std_logic_1164.all; package conversions is function sulv_to_natural(x : std_ulogic_vector) return natural; function natural_to_sulv(n, bits : natural) return std_ulogic_vector; end conversions; package body conversions is function sulv_to_natural(x : std_ulogic_vector) return natural is variable n : natural := 0; variable failure : boolean := false; begin assert (x'high - x'low + 1) <= 31 report "Range of sulv_to_natural argument exceeds natural range" severity error; for i in x'range loop n := n * 2; case x(i) is
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when '1' | 'H' => n := n + 1; when '0' | 'L' => null; when others => failure := true; end case; end loop; assert not failure report "sulv_to_natural cannot convert indefinite std_ulogic_vector" severity error; if failure then return 0; else return n; end if; end sulv_to_natural; function natural_to_sulv(n, bits : natural) return std_ulogic_vector is variable x : std_ulogic_vector(bits-1 downto 0) :=
(others => '0'); variable tempn : natural := n; begin for i in x'reverse_range loop if (tempn mod 2) = 1 then x(i) := '1'; end if; tempn := tempn / 2; end loop; return x; end natural_to_sulv; end conversions;
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VHDL02 example
-------------------------------------------------------------------------
-- Source: sp_syn_ram_protected.vhd
-- Component: VHDL synchronous, single-port RAM
-- Remarks: Various VHDL examples: random access memory (RAM)
-------------------------------------------------------------------------
LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
USE ieee.numeric_std.ALL;
ENTITY sp_syn_ram_protected IS
GENERIC (
data_width : positive := 8;
addr_width : positive := 3
);
PORT (
inclk : IN std_logic;
outclk : IN std_logic;
we : IN std_logic;
addr : IN unsigned(addr_width-1 DOWNTO 0);
data_in : IN std_logic_vector(data_width-1 DOWNTO 0);
data_out : OUT std_logic_vector(data_width-1 DOWNTO 0)
);
END sp_syn_ram_protected;
ARCHITECTURE intarch OF sp_syn_ram_protected IS
TYPE mem_type IS PROTECTED
PROCEDURE write ( data : IN std_logic_vector(data_width-1 downto 0);
addr : IN unsigned(addr_width-1 DOWNTO 0));
IMPURE FUNCTION read ( addr : IN unsigned(addr_width-1 DOWNTO 0))
RETURN
std_logic_vector;
END PROTECTED mem_type;
TYPE mem_type IS PROTECTED BODY
TYPE mem_array IS ARRAY (0 TO 2**addr_width-1) OF
std_logic_vector(data_width-1 DOWNTO 0);
VARIABLE mem : mem_array;
PROCEDURE write ( data : IN std_logic_vector(data_width-1 downto 0);
addr : IN unsigned(addr_width-1 DOWNTO 0)) IS
BEGIN
mem(to_integer(addr)) := data;
END;
IMPURE FUNCTION read ( addr : IN unsigned(addr_width-1 DOWNTO 0))
RETURN
std_logic_vector IS
BEGIN
return mem(to_integer(addr));
END;
END PROTECTED BODY mem_type;
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SHARED VARIABLE memory : mem_type;
BEGIN
ASSERT data_width <= 32
REPORT "### Illegal data width detected"
SEVERITY failure;
control_proc : PROCESS (inclk, outclk)
BEGIN
IF (inclk'event AND inclk = '1') THEN
IF (we = '1') THEN
memory.write(data_in, addr);
END IF;
END IF;
IF (outclk'event AND outclk = '1') THEN
data_out <= memory.read(addr);
END IF;
END PROCESS;
END intarch;
-------------------------------------------------------------------------
-- Source: ram_tb.vhd
-- Component: VHDL testbench for RAM memory example
-- Remarks: Simple VHDL example: random access memory (RAM)
-------------------------------------------------------------------------
LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
USE ieee.numeric_std.ALL;
ENTITY ram_tb IS
END ram_tb;
ARCHITECTURE testbench OF ram_tb IS
-------------------------------------------
-- Component declaration single-port RAM
-------------------------------------------
COMPONENT sp_syn_ram_protected
GENERIC (
data_width : positive := 8;
addr_width : positive := 3
);
PORT (
inclk : IN std_logic;
outclk : IN std_logic;
we : IN std_logic;
addr : IN unsigned(addr_width-1 DOWNTO 0);
data_in : IN std_logic_vector(data_width-1 DOWNTO 0);
data_out : OUT std_logic_vector(data_width-1 DOWNTO 0)
);
END COMPONENT;
-------------------------------------------
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-- Intermediate signals and constants
-------------------------------------------
SIGNAL addr : unsigned(19 DOWNTO 0);
SIGNAL inaddr : unsigned(3 DOWNTO 0);
SIGNAL outaddr : unsigned(3 DOWNTO 0);
SIGNAL data_in : unsigned(31 DOWNTO 0);
SIGNAL data_in1 : std_logic_vector(7 DOWNTO 0);
SIGNAL data_sp1 : std_logic_vector(7 DOWNTO 0);
SIGNAL we : std_logic;
SIGNAL clk : std_logic;
CONSTANT clk_pd : time := 100 ns;
BEGIN
---------------------------------------------------
-- instantiations of single-port RAM architectures.
-- All architectures behave equivalently, but they
-- have different implementations. The signal-based
-- architecture (rtl) is not a recommended style.
---------------------------------------------------
spram1 : entity work.sp_syn_ram_protected
GENERIC MAP (
data_width => 8,
addr_width => 12)
PORT MAP (
inclk => clk,
outclk => clk,
we => we,
addr => addr(11 downto 0),
data_in => data_in1,
data_out => data_sp1);
-------------------------------------------
-- clock generator
-------------------------------------------
clock_driver : PROCESS
BEGIN
clk <= '0';
WAIT FOR clk_pd / 2;
LOOP
clk <= '1', '0' AFTER clk_pd / 2;
WAIT FOR clk_pd;
END LOOP;
END PROCESS;
-------------------------------------------
-- data-in process
-------------------------------------------
datain_drivers : PROCESS(data_in)
BEGIN
data_in1 <= std_logic_vector(data_in(7 downto 0));
END PROCESS;
-------------------------------------------
-- simulation control process
-------------------------------------------
ctrl_sim : PROCESS
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BEGIN
FOR i IN 0 TO 1023 LOOP
we <= '1';
data_in <= to_unsigned(9000 + i, data_in'length);
addr <= to_unsigned(i, addr'length);
inaddr <= to_unsigned(i, inaddr'length);
outaddr <= to_unsigned(i, outaddr'length);
WAIT UNTIL clk'EVENT AND clk = '0';
WAIT UNTIL clk'EVENT AND clk = '0';
data_in <= to_unsigned(7 + i, data_in'length);
addr <= to_unsigned(1 + i, addr'length);
inaddr <= to_unsigned(1 + i, inaddr'length);
WAIT UNTIL clk'EVENT AND clk = '0';
WAIT UNTIL clk'EVENT AND clk = '0';
data_in <= to_unsigned(3, data_in'length);
addr <= to_unsigned(2 + i, addr'length);
inaddr <= to_unsigned(2 + i, inaddr'length);
WAIT UNTIL clk'EVENT AND clk = '0';
WAIT UNTIL clk'EVENT AND clk = '0';
data_in <= to_unsigned(30330, data_in'length);
addr <= to_unsigned(3 + i, addr'length);
inaddr <= to_unsigned(3 + i, inaddr'length);
WAIT UNTIL clk'EVENT AND clk = '0';
WAIT UNTIL clk'EVENT AND clk = '0';
we <= '0';
addr <= to_unsigned(i, addr'length);
outaddr <= to_unsigned(i, outaddr'length);
WAIT UNTIL clk'EVENT AND clk = '0';
WAIT UNTIL clk'EVENT AND clk = '0';
addr <= to_unsigned(1 + i, addr'length);
outaddr <= to_unsigned(1 + i, outaddr'length);
WAIT UNTIL clk'EVENT AND clk = '0';
WAIT UNTIL clk'EVENT AND clk = '0';
addr <= to_unsigned(2 + i, addr'length);
outaddr <= to_unsigned(2 + i, outaddr'length);
WAIT UNTIL clk'EVENT AND clk = '0';
WAIT UNTIL clk'EVENT AND clk = '0';
addr <= to_unsigned(3 + i, addr'length);
outaddr <= to_unsigned(3 + i, outaddr'length);
WAIT UNTIL clk'EVENT AND clk = '0';
WAIT UNTIL clk'EVENT AND clk = '0';
END LOOP;
ASSERT false
REPORT "### End of Simulation!"
SEVERITY failure;
END PROCESS;
END testbench;
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Affecting Performance by Cancelling Scheduled Events
Affecting Performance by Cancelling Scheduled
Events
Performance will suffer if events are scheduled far into the future but then cancelled before they take effect. This situation will act like a memory leak and slow down simulation.
In VHDL this situation can occur several ways. The most common are waits with time-out clauses and projected waveforms in signal assignments.
The following code shows a wait with a time-out: signals synch : bit := '0';
...
p: process begin wait for 10 ms until synch = 1; end process; synch <= not synch after 10 ns;
At time 0, process p makes an event for time 10ms. When synch goes to 1 at 10 ns, the event at
10 ms is marked as cancelled but not deleted, and a new event is scheduled at 10ms + 10ns. The cancelled events are not reclaimed until time 10ms is reached and the cancelled event is processed. As a result there will be 500000 (10ms/20ns) cancelled but un-deleted events. Once
10ms is reached, memory will no longer increase because the simulator will be reclaiming events as fast as they are added.
For projected waveforms the following would behave the same way: signals synch : bit := '0';
...
p: process(synch) begin
output <= '0', '1' after 10ms; end process; synch <= not synch after 10 ns;
Converting an Integer Into a bit_vector
The following code demonstrates how to convert an integer into a bit_vector.
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library ieee; use ieee.numeric_bit.ALL; entity test is end test; architecture only of test is signal s1 : bit_vector(7 downto 0); signal int : integer := 45; begin p:process begin wait for 10 ns; s1 <= bit_vector(to_signed(int,8)); end process p; end only;
VHDL Simulation
Converting an Integer Into a bit_vector
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Chapter 6
Verilog and SystemVerilog Simulation
This chapter describes how to compile and simulate Verilog and SystemVerilog designs with
ModelSim. ModelSim implements the Verilog language as defined by the IEEE Standards
1364-1995 and 1364-2005. We recommend that you obtain these specifications for reference.
The following functionality is partially implemented in ModelSim:
•
Verilog Procedural Interface (VPI) (see
/<install_dir>/modeltech/docs/technotes/Verilog_VPI.note for details)
•
IEEE Std P1800-2005 SystemVerilog (see
/<install_dir>/modeltech/docs/technotes/sysvlog.note for implementation details)
Terminology
This chapter uses the term “Verilog” to represent both Verilog and SystemVerilog, unless otherwise noted.
Basic Verilog Flow
Simulating Verilog designs with ModelSim includes four general steps:
1. Compile your Verilog code into one or more libraries using the vlog command. See
for details.
2. Load your design with the vsim command. See
Simulating Verilog Designs for details.
3. Run and debug your design.
Compiling Verilog Files
The first time you compile a design there is a two-step process:
1. Create a working library with vlib or select File > New > Library.
2. Compile the design using vlog or select Compile > Compile.
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Creating a Working Library
Before you can compile your design, you must create a library in which to store the compilation results. Use the vlib command or select File > New > Library to create a new library. For example:
vlib work
This creates a library named work. By default compilation results are stored in the work library.
The work library is actually a subdirectory named work. This subdirectory contains a special file named _info. Do not create libraries using UNIX commands – always use the vlib.
See
Design Libraries for additional information on working with libraries.
Invoking the Verilog Compiler
The Verilog compiler, vlog, compiles Verilog source code into retargetable, executable code.
The library format is compatible across all supported platforms, and you can simulate your design on any platform without having to recompile your design.
As the design compiles, the resulting object code for modules and UDPs is generated into a library. As noted above, the compiler places results into the work library by default. You can specify an alternate library with the -work argument.
Example 6-1. Invocation of the Verilog Compiler
Here is a sample invocation of vlog:
vlog top.v +libext+.v+.u -y vlog_lib
After compiling top.v, vlog will scan the vlog_lib library for files with modules with the same name as primitives referenced, but undefined in top.v. The use of +libext+.v+.u implies filenames with a .v or .u suffix (any combination of suffixes may be used). Only referenced definitions will be compiled.
Parsing SystemVerilog Keywords
With standard Verilog files (<filename>.v), vlog will not automatically parse SystemVerilog keywords. SystemVerilog keywords are parsed when any of the following situations exists:
• any file within the design contains the .sv file extension,
• the -sv argument is used with the vlog command,
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• the Use System Verilog option is selected in the Verilog tab of the Compiler Options dialog. Access this dialog by selecting Compile > Compile Options from the Main window menu bar.
Figure 6-1. Selecting ‘Use System Verilog’ Compile Option
Here are two examples of the vlog command that will enable SystemVerilog features and keywords in ModelSim:
vlog testbench.sv top.v memory.v cache.v
vlog -sv testbench.v proc.v
In the first example, the .sv extension for testbench automatically instructs ModelSim to parse
SystemVerilog keywords. The -sv option used in the second example enables SystemVerilog features and keywords.
Though a primary goal of the SystemVerilog standardization efforts has been to ensure full backward compatibility with the Verilog standard, there is an issue with keywords.
SystemVerilog adds several new keywords to the Verilog language (see Table B-1 in Appendix
B of the P1800 SystemVerilog standard). If your design uses one of these keywords as a regular identifier for a variable, module, task, function, etc., your design will not compile in ModelSim.
Incremental Compilation
ModelSim Verilog supports incremental compilation of designs. Unlike other Verilog simulators, there is no requirement that you compile the entire design in one invocation of the compiler.
You are not required to compile your design in any particular order (unless you are using
SystemVerilog packages; see note below) because all module and UDP instantiations and external hierarchical references are resolved when the design is loaded by the simulator.
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Note
Compilation order may matter when using SystemVerilog packages. As stated in the
IEEE std p1800-2005 LRM, section entitled Referencing data in packages, which states:
"Packages must exist in order for the items they define to be recognized by the scopes in which they are imported.”
Incremental compilation is made possible by deferring these bindings, and as a result some errors cannot be detected during compilation. Commonly, these errors include: modules that were referenced but not compiled, incorrect port connections, and incorrect hierarchical references.
Example 6-2. Incremental Compilation Example
Contents of testbench.sv
module testbench; timeunit 1ns; timeprecision 10ps; bit d=1, clk = 0; wire q; initial for (int cycles=0; cycles < 100; cycles++)
#100 clk = !clk; design dut(q, d, clk); endmodule
Contents of design.v: module design(output bit q, input bit d, clk); timeunit 1ns; timeprecision 10ps; always @(posedge clk) q = d; endmodule
Compile the design incrementally as follows:
ModelSim> vlog testbench.sv
.
# Top level modules:
# testbench
ModelSim> vlog -sv test1.v
.
# Top level modules:
# dut
Note that the compiler lists each module as a top-level module, although, ultimately, only
testbench is a top-level module. If a module is not referenced by another module compiled in the same invocation of the compiler, then it is listed as a top-level module. This is just an informative message and can be ignored during incremental compilation.
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The message is more useful when you compile an entire design in one invocation of the compiler and need to know the top-level module names for the simulator. For example,
% vlog top.v and2.v or2.v
-- Compiling module top
-- Compiling module and2
-- Compiling module or2
Top level modules: top
Automatic Incremental Compilation with -incr
The most efficient method of incremental compilation is to manually compile only the modules that have changed. However, this is not always convenient, especially if your source files have compiler directive interdependencies (such as macros). In this case, you may prefer to compile your entire design along with the -incr argument. This causes the compiler to automatically determine which modules have changed and generate code only for those modules.
The following is an example of how to compile a design with automatic incremental compilation:
% vlog -incr top.v and2.v or2.v
-- Compiling module top
-- Compiling module and2
-- Compiling module or2
Top level modules: top
Now, suppose that you modify the functionality of the or2 module:
% vlog -incr top.v and2.v or2.v
-- Skipping module top
-- Skipping module and2
-- Compiling module or2
Top level modules: top
The compiler informs you that it skipped the modules top and and2, and compiled or2.
Automatic incremental compilation is intelligent about when to compile a module. For example, changing a comment in your source code does not result in a recompile; however, changing the compiler command line arguments results in a recompile of all modules.
Note
Changes to your source code that do not change functionality but that do affect source code line numbers (such as adding a comment line) will cause all affected modules to be recompiled. This happens because debug information must be kept current so that
ModelSim can trace back to the correct areas of the source code.
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Library Usage
All modules and UDPs in a Verilog design must be compiled into one or more libraries. One library is usually sufficient for a simple design, but you may want to organize your modules into various libraries for a complex design. If your design uses different modules having the same name, then you are required to put those modules in different libraries because design unit names must be unique within a library.
The following is an example of how you may organize your ASIC cells into one library and the rest of your design into another:
% vlib work
% vlib asiclib
% vlog -work asiclib and2.v or2.v
-- Compiling module and2
-- Compiling module or2
Top level modules: and2 or2
% vlog top.v
-- Compiling module top
Top level modules: top
Note that the first compilation uses the -work asiclib argument to instruct the compiler to place the results in the asiclib library rather than the default work library.
Library Search Rules for vlog
Since instantiation bindings are not determined at compile time, you must instruct the simulator to search your libraries when loading the design. The top-level modules are loaded from the library named work unless you prefix the modules with the <library>. option. All other
Verilog instantiations are resolved in the following order:
•
Search libraries specified with -Lf arguments in the order they appear on the command line.
•
Search the library specified in the
Verilog-XL uselib Compiler Directive section.
•
Search libraries specified with -L arguments in the order they appear on the command line.
•
Search the work library.
•
Search the library explicitly named in the special escaped identifier instance name.
Handling Sub-Modules with Common Names
Sometimes in one design you need to reference two different modules that have the same name.
This situation can occur if you have hierarchical modules organized into separate libraries, and
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you have commonly-named sub-modules in the libraries that have different definitions. This may happen if you are using vendor-supplied libraries.
For example, say you have the following design configuration:
Example 6-3. Sub-Modules with Common Names
top modA modB lib1: modA cellX lib2: modB cellX
The normal library search rules will fail in this situation. For example, if you load the design as follows:
vsim -L lib1 -L lib2 top
both instantiations of cellX resolve to the lib1 version of cellX. On the other hand, if you specify
-L lib2 -L lib1, both instantiations of cellX resolve to the lib2 version of cellX.
To handle this situation, ModelSim implements a special interpretation of the expression -L
work. When you specify -L work first in the search library arguments you are directing vsim to search for the instantiated module or UDP in the library that contains the module that does the instantiation.
In the example above you would invoke vsim as follows:
vsim -L work -L lib1 -L lib2 top
SystemVerilog Multi-File Compilation Issues
Declarations in Compilation Unit Scope
SystemVerilog allows the declaration of types, variables, functions, tasks, and other constructs in compilation unit scope ($unit). The visibility of declarations in $unit scope does not extend outside the current compilation unit. Thus, it is important to understand how compilation units are defined by the tool during compilation.
By default, vlog operates in Single File Compilation Unit mode (SFCU). This means the visibility of declarations in $unit scope terminates at the end of each source file. Visibility does not carry forward from one file to another, except when a module, interface, or package
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declaration begins in one file and ends in another file. In that case, the compilation unit spans from the file containing the beginning of the declaration to the file containing the end of the declaration.
vlog also supports a non-default behavior called Multi File Compilation Unit mode (MFCU). In
MFCU mode, vlog compiles all files given on the command line into one compilation unit. You can invoke vlog in MFCU mode as follows:
•
For a specific compilation -- with the -mfcu argument to vlog .
•
For all compilations -- by setting the variable MultiFileCompilationUnit = 1 in the
modelsim.ini file.
By using either of these methods, you allow declarations in $unit scope to remain in effect throughout the compilation of all files.
In case you have made MFCU the default behavior by setting MultiFileCompilationUnit = 1 in your modelsim.ini file, it is possible to override the default behavior on specific compilations by using the -sfcu argument to vlog .
Macro Definitions and Compiler Directives in Compilation Unit
Scope
According to the SystemVerilog IEEE Std p1800-2005 LRM, the visibility of macro definitions and compiler directives span the lifetime of a single compilation unit. By default, this means the definitions of macros and settings of compiler directives terminate at the end of each source file.
They do not carry forward from one file to another, except when a module, interface, or package declaration begins in one file and ends in another file. In that case, the compilation unit spans from the file containing the beginning of the definition to the file containing the end of the definition.
See
Declarations in Compilation Unit Scope for instructions on how to control vlog's handling
of compilation units.
Note
Compiler directives revert to their default values at the end of a compilation unit.
If a compiler directive is specified as an option to the compiler, this setting is used for all compilation units present in the current compilation.
Verilog-XL Compatible Compiler Arguments
The compiler arguments listed below are equivalent to Verilog-XL arguments and may ease the porting of a design to ModelSim. See the vlog command for a description of each argument.
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+define+<macro_name>[=<macro_text>]
+delay_mode_distributed
+delay_mode_path
+delay_mode_unit
+delay_mode_zero
-f <filename>
+incdir+<directory>
+mindelays
+maxdelays
+nowarn<mnemonic>
+typdelays
-u
Arguments Supporting Source Libraries
The compiler arguments listed below support source libraries in the same manner as Verilog-
XL. See the vlog command for a description of each argument.
Note that these source libraries are very different from the libraries that the ModelSim compiler uses to store compilation results. You may find it convenient to use these arguments if you are porting a design to ModelSim or if you are familiar with these arguments and prefer to use them.
Source libraries are searched after the source files on the command line are compiled. If there are any unresolved references to modules or UDPs, then the compiler searches the source libraries to satisfy them. The modules compiled from source libraries may in turn have additional unresolved references that cause the source libraries to be searched again. This process is repeated until all references are resolved or until no new unresolved references are found. Source libraries are searched in the order they appear on the command line.
-v <filename>
-y <directory>
+libext+<suffix>
+librescan
+nolibcell
-R [<simargs>]
Verilog-XL uselib Compiler Directive
The `uselib compiler directive is an alternative source library management scheme to the -v, -y, and +libext compiler arguments. It has the advantage that a design may reference different modules having the same name. You compile designs that contain `uselib directive statements using the -compile_uselibs argument (described below) to vlog .
The syntax for the `uselib directive is:
`uselib <library_reference>...
where <library_reference> can be one or more of the following:
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•
dir=<library_directory>, which is equivalent to the command line argument:
-y <library_directory>
•
file=<library_file>, which is equivalent to the command line argument:
-v <library_file>
•
libext=<file_extension>, which is equivalent to the command line argument:
+libext+<file_extension>
•
lib=<library_name>, which references a library for instantiated objects. This behaves similarly to a LIBRARY/USE clause in VHDL. You must ensure the correct mappings are set up if the library does not exist in the current working directory. The
-compile_uselibs argument does not affect this usage of `uselib.
For example, the following directive
`uselib dir=/h/vendorA libext=.v
is equivalent to the following command line arguments:
-y /h/vendorA +libext+.v
Since the `uselib directives are embedded in the Verilog source code, there is more flexibility in defining the source libraries for the instantiations in the design. The appearance of a `uselib directive in the source code explicitly defines how instantiations that follow it are resolved, completely overriding any previous `uselib directives.
-compile_uselibs Argument
Use the -compile_uselibs argument to vlog to reference `uselib directives. The argument finds the source files referenced in the directive, compiles them into automatically created object libraries, and updates the modelsim.ini file with the logical mappings to the libraries.
When using -compile_uselibs, ModelSim determines into which directory to compile the object libraries by choosing, in order, from the following three values:
•
The directory name specified by the -compile_uselibs argument. For example,
-compile_uselibs=./mydir
•
The directory specified by the MTI_USELIB_DIR environment variable (see
•
A directory named mti_uselibs that is created in the current working directory
The following code fragment and compiler invocation show how two different modules that have the same name can be instantiated within the same design:
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module top;
`uselib dir=/h/vendorA libext=.v
NAND2 u1(n1, n2, n3);
`uselib dir=/h/vendorB libext=.v
NAND2 u2(n4, n5, n6); endmodule
vlog -compile_uselibs top
This allows the NAND2 module to have different definitions in the vendorA and vendorB libraries.
uselib is Persistent
As mentioned above, the appearance of a `uselib directive in the source code explicitly defines how instantiations that follow it are resolved. This may result in unexpected consequences. For example, consider the following compile command:
vlog -compile_uselibs dut.v srtr.v
Assume that dut.v contains a `uselib directive. Since srtr.v is compiled after dut.v, the `uselib directive is still in effect. When srtr is loaded it is using the `uselib directive from dut.v to decide where to locate modules. If this is not what you intend, then you need to put an empty
`uselib at the end of dut.v to "close" the previous `uselib statement.
Verilog Configurations
The Verilog 2001 specification added configurations. Configurations specify how a design is
"assembled" during the elaboration phase of simulation. Configurations actually consist of two pieces: the library mapping and the configuration itself. The library mapping is used at compile time to determine into which libraries the source files are to be compiled. Here is an example of a simple library map file: library work ../top.v; library rtlLib lrm_ex_top.v; library gateLib lrm_ex_adder.vg; library aLib lrm_ex_adder.v;
Here is an example of a library map file that uses -incdir: library lib1 src_dir/*.v -incdir ../include_dir2, ../, my_incdir;
The name of the library map file is arbitrary. You specify the library map file using the -libmap argument to the vlog command. Alternatively, you can specify the file name as the first item on the vlog command line, and the compiler will read it as a library map file.
The library map file must be compiled along with the Verilog source files. Multiple map files are allowed but each must be preceded by the -libmap argument.
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The library map file and the configuration can exist in the same or different files. If they are separate, only the map file needs the -libmap argument. The configuration is treated as any other Verilog source file.
Configurations and the Library Named work
The library named “work” is treated specially by ModelSim (see
for details) for Verilog configurations. Consider the following code example: config cfg; design top; instance top.u1 use work.u1; endconfig
In this case, work.u1 indicates to load u1 from the current library.
Verilog Generate Statements
The Verilog 2001 rules for generate statements had numerous inconsistencies and ambiguities.
As a result, ModelSim implements the rules that have been adopted for Verilog 2005. Most of the rules are backwards compatible, but there is one key difference related to name visibility.
Name Visibility in Generate Statements
Consider the following code example: module m; parameter p = 1; generate if (p) integer x = 1; else real x = 2.0; endgenerate initial $display(x); endmodule
This code sample is legal under 2001 rules. However, it is illegal under the 2005 rules and will cause an error in ModelSim. Under the new rules, you cannot hierarchically reference a name in an anonymous scope from outside that scope. In the example above, x does not propagate its visibility upwards, and each condition alternative is considered to be an anonymous scope.
To fix the code such that it will simulate properly in ModelSim, write it like this instead:
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module m; parameter p = 1; if (p) begin:s end integer x = 1; else begin:s real x = 2.0; end initial $display(s.x); endmodule
Since the scope is named in this example, normal hierarchical resolution rules apply and the code is fine.
Note too that the keywords generate - endgenerate are optional under the 2005 rules and are excluded in the second example.
Simulating Verilog Designs
A Verilog design is ready for simulation after it has been compiled with vlog. The simulator may then be invoked with the names of the top-level modules (many designs contain only one top-level module). For example, if your top-level modules are "testbench" and "globals", then invoke the simulator as follows:
vsim testbench globals
After the simulator loads the top-level modules, it iteratively loads the instantiated modules and
UDPs in the design hierarchy, linking the design together by connecting the ports and resolving hierarchical references. By default all modules and UDPs are loaded from the library named
work. Modules and UDPs from other libraries can be specified using the -L or -Lf arguments to
vsim (see
On successful loading of the design, the simulation time is set to zero, and you must enter a run command to begin simulation. Commonly, you enter run -all to run until there are no more simulation events or until $finish is executed in the Verilog code. You can also run for specific time periods (e.g., run 100 ns). Enter the quit command to exit the simulator.
Simulator Resolution Limit (Verilog)
The simulator internally represents time as a 64-bit integer in units equivalent to the smallest unit of simulation time, also known as the simulator resolution limit. The resolution limit defaults to the smallest time precision found among all of the `timescale compiler directives in the design. Here is an example of a `timescale directive:
`timescale 1 ns / 100 ps
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The first number is the time units and the second number is the time precision. The directive above causes time values to be read as ns and to be rounded to the nearest 100 ps.
Time units and precision can also be specified with SystemVerilog keywords as follows:
timeunit 1 ns timeprecision 100 ps
Modules Without Timescale Directives
You may encounter unexpected behavior if your design contains some modules with timescale directives and others without. The time units for modules without a timescale directive default to the simulator resolution. For example, say you have the two modules shown in the table below:
Table 6-1. Sample Modules With and Without Timescale Directive
Module 1 Module 2
`timescale 1 ns / 10 ps module mod2 (set); module mod1 (set); output set; reg set; parameter d = 1.55; initial begin set = 1'bz;
#d set = 1'b0;
#d set = 1'b1; end endmodule output set; reg set; parameter d = 1.55; initial begin set = 1'bz;
#d set = 1'b0;
#d set = 1'b1; end endmodule
If you invoke vsim as vsim mod2 mod1 then Module 1 sets the simulator resolution to 10 ps.
Module 2 has no timescale directive, so the time units default to the simulator resolution, in this case 10 ps. If you watched /mod1/set and /mod2/set in the Wave window, you’d see that in
Module 1 it transitions every 1.55 ns as expected (because of the 1 ns time unit in the timescale directive). However, in Module 2, set transitions every 20 ps. That’s because the delay of 1.55
in Module 2 is read as 15.5 ps and is rounded up to 20 ps.
In such cases ModelSim will issue the following warning message during elaboration:
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** Warning: (vsim-3010) [TSCALE] - Module 'mod1' has a `timescale directive in effect, but previous modules do not.
If you invoke vsim as vsim mod1 mod2, the simulation results would be the same but
ModelSim would produce a different warning message:
** Warning: (vsim-3009) [TSCALE] - Module 'mod2' does not have a
`timescale directive in effect, but previous modules do.
These warnings should ALWAYS be investigated.
If the design contains no `timescale directives, then the resolution limit and time units default to the value specified by the
Resolution variable in the modelsim.ini file. (The variable is set to 1
ps by default.)
-timescale Option
The -timescale option can be used with the vlog and vopt to specifies the default timescale for modules not having an explicit `timescale directive in effect during compilation. The format of the -timescale argument is the same as that of the `timescale directive
-timescale <time_units>/<time_precision>
The format for <time_units> and <time_precision> is <n><units>. The value of <n> must be
1, 10, or 100. The value of <units> must be fs, ps, ns, us, ms, or s. In addition, the <time_units> must be greater than or equal to the <time_precision>. For example:
-timescale "1ns / 1ps"
The argument above needs quotes because it contains white space.
Multiple Timescale Directives
As alluded to above, your design can have multiple timescale directives. The timescale directive takes effect where it appears in a source file and applies to all source files which follow in the same
vlog
command. Separately compiled modules can also have different timescales. The simulator determines the smallest timescale of all the modules in a design and uses that as the simulator resolution.
timescale, -t, and Rounding
The optional vsim argument -t sets the simulator resolution limit for the overall simulation. If the resolution set by -t is larger than the precision set in a module, the time values in that module are rounded up. If the resolution set by -t is smaller than the precision of the module, the precision of that module remains whatever is specified by the `timescale directive. Consider the following code:
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`timescale 1 ns / 100 ps module foo; initial
#12.536 $display
The list below shows three possibilities for -t and how the delays in the module would be handled in each case:
•
-t not set
The delay will be rounded to 12.5 as directed by the module’s ‘timescale directive.
•
-t is set to 1 fs
The delay will be rounded to 12.5. Again, the module’s precision is determined by the
‘timescale directive. ModelSim does not override the module’s precision.
•
-t is set to 1 ns
The delay will be rounded to 12. The module’s precision is determined by the -t setting.
ModelSim has no choice but to round the module’s time values because the entire simulation is operating at 1 ns.
Choosing the Resolution for Verilog
You should choose the coarsest resolution limit possible that does not result in undesired rounding of your delays. The time precision should not be unnecessarily small because it will limit the maximum simulation time limit, and it will degrade performance in some cases.
Event Ordering in Verilog Designs
Event-based simulators such as ModelSim may process multiple events at a given simulation time. The Verilog language is defined such that you cannot explicitly control the order in which simultaneous events are processed. Unfortunately, some designs rely on a particular event order, and these designs may behave differently than you expect.
Event Queues
Section 5 of the IEEE Std 1364-1995 LRM defines several event queues that determine the order in which events are evaluated. At the current simulation time, the simulator has the following pending events:
• active events
• inactive events
• non-blocking assignment update events
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• monitor events
• future events o inactive events o non-blocking assignment update events
The LRM dictates that events are processed as follows – 1) all active events are processed; 2) the inactive events are moved to the active event queue and then processed; 3) the non-blocking events are moved to the active event queue and then processed; 4) the monitor events are moved to the active queue and then processed; 5) simulation advances to the next time where there is an inactive event or a non-blocking assignment update event.
Within the active event queue, the events can be processed in any order, and new active events can be added to the queue in any order. In other words, you cannot control event order within the active queue. The example below illustrates potential ramifications of this situation.
Say you have these four statements:
1. always@(q) p = q;
2. always @(q) p2 = not q;
3. always @(p or p2) clk = p and p2;
4. always @(posedge clk) and current values as follows: q = 0, p = 0, p2=1
The tables below show two of the many valid evaluations of these statements. Evaluation events are denoted by a number where the number is the statement to be evaluated. Update events are denoted <name>(old->new) where <name> indicates the reg being updated and new is the updated value.\
Table 6-2. Evaluation 1 of always Statements
Event being processed Active event queue
q(0 -> 1)
1 p(0 -> 1)
3 clk(0 -> 1)
4
2 q(0 -> 1)
1, 2 p(0 -> 1), 2
3, 2 clk(0 -> 1), 2
4, 2
2 p2(1 -> 0)
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Table 6-2. Evaluation 1 of always Statements (cont.)
Event being processed Active event queue
p2(1 -> 0)
3 clk(1 -> 0)
3 clk(1 -> 0)
<empty>
Table 6-3. Evaluation 2 of always Statement
Event being processed Active event queue
q(0 -> 1)
1 q(0 -> 1)
1, 2 p(0 -> 1), 2 p2(1 -> 0), p(0 -> 1) 2 p(0 -> 1) p2(1
−>
0)
3
3, p2(1 -> 0)
3
<empty> (clk doesn’t change)
Again, both evaluations are valid. However, in Evaluation 1, clk has a glitch on it; in Evaluation
2, clk doesn’t. This indicates that the design has a zero-delay race condition on clk.
Controlling Event Queues with Blocking or Non-Blocking
Assignments
The only control you have over event order is to assign an event to a particular queue. You do this via blocking or non-blocking assignments.
Blocking Assignments
Blocking assignments place an event in the active, inactive, or future queues depending on what type of delay they have:
• a blocking assignment without a delay goes in the active queue
• a blocking assignment with an explicit delay of 0 goes in the inactive queue
• a blocking assignment with a non-zero delay goes in the future queue
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Non-Blocking Assignments
A non-blocking assignment goes into either the non-blocking assignment update event queue or the future non-blocking assignment update event queue. (Non-blocking assignments with no delays and those with explicit zero delays are treated the same.)
Non-blocking assignments should be used only for outputs of flip-flops. This insures that all outputs of flip-flops do not change until after all flip-flops have been evaluated. Attempting to use non-blocking assignments in combinational logic paths to remove race conditions may only cause more problems. (In the preceding example, changing all statements to non-blocking assignments would not remove the race condition.) This includes using non-blocking assignments in the generation of gated clocks.
The following is an example of how to properly use non-blocking assignments.
gen1: always @(master) clk1 = master; gen2: always @(clk1) clk2 = clk1; f1 : always @(posedge clk1) begin q1 <= d1; end f2: always @(posedge clk2) begin q2 <= q1; end
If written this way, a value on d1 always takes two clock cycles to get from d1 to q2.
If you change clk1 = master and clk2 = clk1 to non-blocking assignments or q2 <= q1 and q1
<= d1 to blocking assignments, then d1 may get to q2 is less than two clock cycles.
Debugging Event Order Issues
Since many models have been developed on Verilog-XL, ModelSim tries to duplicate Verilog-
XL event ordering to ease the porting of those models to ModelSim. However, ModelSim does not match Verilog-XL event ordering in all cases, and if a model ported to ModelSim does not behave as expected, then you should suspect that there are event order dependencies.
ModelSim helps you track down event order dependencies with the following compiler arguments: -compat, -hazards, and -keep_delta.
See the
vlog
command for descriptions of -compat and -hazards.
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Hazard Detection
The -hazard argument to vsim detects event order hazards involving simultaneous reading and writing of the same register in concurrently executing processes. vsim detects the following kinds of hazards:
•
WRITE/WRITE — Two processes writing to the same variable at the same time.
•
READ/WRITE — One process reading a variable at the same time it is being written to by another process. ModelSim calls this a READ/WRITE hazard if it executed the read first.
•
WRITE/READ — Same as a READ/WRITE hazard except that ModelSim executed the write first.
vsim issues an error message when it detects a hazard. The message pinpoints the variable and the two processes involved. You can have the simulator break on the statement where the hazard is detected by setting the break on assertion level to Error.
To enable hazard detection you must invoke vlog with the -hazards argument when you compile your source code and you must also invoke vsim with the -hazards argument when you simulate.
Note
Enabling -hazards implicitly enables the -compat argument. As a result, using this argument may affect your simulation results.
Hazard Detection and Optimization Levels
In certain cases hazard detection results are affected by the optimization level used in the simulation. Some optimizations change the read/write operations performed on a variable if the transformation is determined to yield equivalent results. Since the hazard detection algorithm doesn’t know whether or not the read/write operations can affect the simulation results, the optimizations can result in different hazard detection results. Generally, the optimizations reduce the number of false hazards by eliminating unnecessary reads and writes, but there are also optimizations that can produce additional false hazards.
Limitations of Hazard Detection
•
Reads and writes involving bit and part selects of vectors are not considered for hazard detection. The overhead of tracking the overlap between the bit and part selects is too high.
•
A WRITE/WRITE hazard is flagged even if the same value is written by both processes.
•
A WRITE/READ or READ/WRITE hazard is flagged even if the write does not modify the variable's value.
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•
Glitches on nets caused by non-guaranteed event ordering are not detected.
•
A non-blocking assignment is not treated as a WRITE for hazard detection purposes.
This is because non-blocking assignments are not normally involved in hazards. (In fact, they should be used to avoid hazards.)
•
Hazards caused by simultaneous forces are not detected.
Negative Timing Check Limits
Verilog supports negative limit values in the $setuphold and $recrem system tasks. These tasks have optional delayed versions of input signals to insure proper evaluation of models with negative timing check limits. Delay values for these delayed nets are determined by the simulator so that valid data is available for evaluation before a clocking signal.
Example 6-4. Negative Timing Check
$setuphold(posedge clk, negedge d, 5, -3, Notifier,,, clk_dly, d_dly);
d violation region
5 3
0 clk
ModelSim calculates the delay for signal d_dly as 4 time units instead of 3. It does this to prevent d_dly and clk_dly from occurring simultaneously when a violation isn’t reported.
ModelSim accepts negative limit checks by default, unlike current versions of Verilog-XL. To match Verilog-XL default behavior (i.e., zeroing all negative timing check limits), use the
+no_neg_tcheck argument to vsim .
Negative Timing Constraint Algorithm
The algorithm ModelSim uses to calculate delays for delayed nets isn’t described in IEEE Std
1364. Rather, ModelSim matches Verilog-XL behavior. The algorithm attempts to find a set of delays so the data net is valid when the clock net transitions and the timing checks are satisfied.
The algorithm is iterative because a set of delays can be selected that satisfies all timing checks for a pair of inputs but then causes mis-ordering of another pair (where both pairs of inputs share a common input). When a set of delays that satisfies all timing checks is found, the delays are said to converge.
Using Delayed Inputs for Timing Checks
By default ModelSim performs timing checks on inputs specified in the timing check. If you want timing checks performed on the delayed inputs, use the +delayed_timing_checks argument with the vsim command.
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Consider an example. This timing check:
$setuphold(posedge clk, posedge t, 20, -12, NOTIFIER,,, clk_dly, t_dly);
reports a timing violation when posedge t occurs in the violation region:
20 -12 t
0 clk
With the +delayed_timing_checks argument, the violation region between the delayed inputs is:
7 t_dly
0
1 clk_dly
Although the check is performed on the delayed inputs, the timing check violation message is adjusted to reference the undelayed inputs. Only the report time of the violation message is noticeably different between the delayed and undelayed timing checks.
By far the greatest difference between these modes is evident when there are conditions on a delayed check event because the condition is not implicitly delayed. Also, timing checks specified without explicit delayed signals are delayed, if necessary, when they reference an input that is delayed for a negative timing check limit.
Other simulators perform timing checks on the delayed inputs. To be compatible, ModelSim supports both methods.
Verilog-XL Compatible Simulator Arguments
The simulator arguments listed below are equivalent to Verilog-XL arguments and may ease the porting of a design to ModelSim. See the vsim command for a description of each argument.
+alt_path_delays
-l <filename>
+maxdelays
+mindelays
+multisource_int_delays
+no_cancelled_e_msg
+no_neg_tchk
+no_notifier
+no_path_edge
+no_pulse_msg
-no_risefall_delaynets
+no_show_cancelled_e
+nosdfwarn
+nowarn<mnemonic>
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+ntc_warn
+pulse_e/<percent>
+pulse_e_style_ondetect
+pulse_e_style_onevent
+pulse_int_e/<percent>
+pulse_int_r/<percent>
+pulse_r/<percent>
+sdf_nocheck_celltype
+sdf_verbose
+show_cancelled_e
+transport_int_delays
+transport_path_delays
+typdelays
Using Escaped Identifiers
ModelSim always converts Verilog escaped identifiers to VHDL syntax.
In Verilog, escaped identifiers start with the backslash character and end with a white space.
Neither the backslash at the beginning or the white space at the end are considered to be a part of the identifier. When a ModelSim displays Verilog escaped identifiers, however, a backslash is added at the end in order to match the VHDL syntax for escaped identifiers. This is because all Verilog escaped identifiers can be easily converted to VHDL but the converse is not true.
So, for example, a Verilog escaped identifier like the following:
\/top/dut/03
will be displayed as follows:
\/top/dut/03\
When entering Verilog identifiers with the ModelSim command line interface, you should use the VHDL syntax, with a backslash at the beginning and end of the identifier.
In Tcl, the backslash is one of a number of characters that have a special meaning. For example,
\n
creates a new line.
When a Tcl command is used in the command line interface, the TCL backslash should be escaped by adding another backslash. For example:
force -freeze /top/ix/iy/\\yw\[1\]\\ 10 0, 01 {50 ns} -r 100
The Verilog identifier, in this example, is \yw[1]. Here, double backslashes are used because it is necessary to escape the square brackets ([]), which have a special meaning in Tcl.
For a more detailed description of special characters in Tcl and how backslashes should be used with those characters, click Help > Tcl Syntax in the menu bar of the graphic interface, or simply open the docs/tcl_help_html/TclCmd directory in your ModelSim installation.
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Cell Libraries
Model Technology passed the ASIC Council’s Verilog test suite and achieved the "Library
Tested and Approved" designation from Si2 Labs. This test suite is designed to ensure Verilog timing accuracy and functionality and is the first significant hurdle to complete on the way to achieving full ASIC vendor support. As a consequence, many ASIC and FPGA vendors’
Verilog cell libraries are compatible with ModelSim Verilog.
The cell models generally contain Verilog "specify blocks" that describe the path delays and timing constraints for the cells. See section 13 in the IEEE Std 1364-1995 for details on specify blocks, and section 14.5 for details on timing constraints. ModelSim Verilog fully implements specify blocks and timing constraints as defined in IEEE Std 1364 along with some Verilog-XL compatible extensions.
SDF Timing Annotation
ModelSim Verilog supports timing annotation from Standard Delay Format (SDF) files. See
Standard Delay Format (SDF) Timing Annotation for details.
Delay Modes
Verilog models may contain both distributed delays and path delays. The delays on primitives,
UDPs, and continuous assignments are the distributed delays, whereas the port-to-port delays specified in specify blocks are the path delays. These delays interact to determine the actual delay observed. Most Verilog cells use path delays exclusively, with the distributed delays set to zero. For example, module and2(y, a, b); input a, b; output y; and(y, a, b); specify
(a => y) = 5;
(b => y) = 5; endspecify endmodule
In the above two-input "and" gate cell, the distributed delay for the "and" primitive is zero, and the actual delays observed on the module ports are taken from the path delays. This is typical for most cells, but a complex cell may require non-zero distributed delays to work properly. Even so, these delays are usually small enough that the path delays take priority over the distributed delays. The rule is that if a module contains both path delays and distributed delays, then the larger of the two delays for each path shall be used (as defined by the IEEE Std 1364). This is the default behavior, but you can specify alternate delay modes with compiler directives and
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arguments. These arguments and directives are compatible with Verilog-XL. Compiler delay mode arguments take precedence over delay mode directives in the source code.
Distributed Delay Mode
In distributed delay mode the specify path delays are ignored in favor of the distributed delays.
Select this delay mode with the +delay_mode_distributed compiler argument or the
`delay_mode_distributed compiler directive.
Path Delay Mode
In path delay mode the distributed delays are set to zero in any module that contains a path delay. Select this delay mode with the +delay_mode_path compiler argument or the
`delay_mode_path compiler directive.
Unit Delay Mode
In unit delay mode the non-zero distributed delays are set to one unit of simulation resolution
(determined by the minimum time_precision argument in all ‘timescale directives in your design or the value specified with the -t argument to vsim), and the specify path delays and timing constraints are ignored. Select this delay mode with the +delay_mode_unit compiler argument or the `delay_mode_unit compiler directive.
Zero Delay Mode
In zero delay mode the distributed delays are set to zero, and the specify path delays and timing constraints are ignored. Select this delay mode with the +delay_mode_zero compiler argument or the `delay_mode_zero compiler directive.
System Tasks and Functions
ModelSim supports system tasks and functions as follows:
•
All system tasks and functions defined in IEEE Std 1364
•
Some system tasks and functions defined in SystemVerilog IEEE std p1800-2005 LRM
•
Several system tasks and functions that are specific to ModelSim
•
Several non-standard, Verilog-XL system tasks
The system tasks and functions listed in this section are built into the simulator, although some designs depend on user-defined system tasks implemented with the Programming Language
Interface (PLI), Verilog Procedural Interface (VPI), or the SystemVerilog DPI (Direct
Programming Interface). If the simulator issues warnings regarding undefined system tasks or functions, then it is likely that these tasks or functions are defined by a PLI/VPI application that must be loaded by the simulator.
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IEEE Std 1364 System Tasks and Functions
The following system tasks and functions are described in detail in the IEEE Std 1364.
Table 6-4. IEEE Std 1364 System Tasks and Functions - 1
Timescale tasks Simulator control tasks
Simulation time functions
Command line input
$printtimescale
$timeformat
$finish
$stop
$realtime
$stime
$test$plusargs
$value$plusargs
$time
Probabilistic distribution functions
Table 6-5. IEEE Std 1364 System Tasks and Functions - 2
Conversion functions
Stochastic analysis tasks
Timing check tasks
$dist_chi_square
$dist_erlang
$bitstoreal
$itor
$q_add
$q_exam
$hold
$nochange
$dist_exponential
$dist_normal
$dist_poisson
$dist_t
$dist_uniform
$random
$realtobits
$rtoi
$signed
$unsigned
$q_full
$q_initialize
$q_remove
$period
$recovery
$setup
$setuphold
$skew
$width
1
$removal
$recrem
1. Verilog-XL ignores the threshold argument even though it is part of the Verilog spec. ModelSim does not ignore this argument. Be careful that you don’t set the threshold argument greater-than-or-equal to the limit argument as that essentially disables the $width check. Note too that you cannot override the threshold argument via SDF annotation.
Display tasks
$display
Table 6-6. IEEE Std 1364 System Tasks
PLA modeling tasks Value change dump
(VCD) file tasks
$async$and$array $dumpall
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Display tasks
Table 6-6. IEEE Std 1364 System Tasks (cont.)
PLA modeling tasks Value change dump
(VCD) file tasks
$displayb
$displayh
$displayo
$monitor
$async$nand$array
$async$or$array
$async$nor$array
$async$and$plane
$dumpfile
$dumpflush
$dumplimit
$dumpoff
$dumpon
$dumpvars
$monitorb
$monitorh
$monitoro
$monitoroff
$monitoron
$strobe
$strobeb
$strobeh
$async$nand$plane
$async$or$plane
$async$nor$plane
$sync$and$array
$sync$nand$array
$sync$or$array
$sync$nor$array
$sync$and$plane
$strobeo
$write
$writeb
$writeh
$writeo
$sync$nand$plane
$sync$or$plane
$sync$nor$plane
File I/O tasks
$fclose
$fdisplay
$fdisplayb
$fdisplayh
$fdisplayo
$feof
$ferror
$fflush
$fgetc
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$fmonitoro
$fopen
$fread
$fscanf
$fseek
$fstrobe
$fstrobeb
$fstrobeh
$fstrobeo
$fwriteh
$fwriteo
$readmemb
$readmemh
$rewind
$sdf_annotate
$sformat
$sscanf
$swrite
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Table 6-7. IEEE Std 1364 File I/O Tasks (cont.)
File I/O tasks
$fgets
$fmonitor
$fmonitorb
$fmonitorh
$ftell
$fwrite
$fwriteb
$swriteb
$swriteh
$swriteo
$ungetc
SystemVerilog System Tasks and Functions
The following ModelSim-supported system tasks and functions are described in detail in the
SystemVerilog IEEE Std p1800-2005 LRM.
Table 6-8. SystemVerilog System Tasks and Functions - 1
Expression size function Range function
$bits $isunbounded
Shortreal conversions
Table 6-9. SystemVerilog System Tasks and Functions - 2
Array querying functions
$shortrealbits
$bitstoshortreal
$dimensions
$left
$right
$low
$high
$increment
$size
Table 6-10. SystemVerilog System Tasks and Functions - 4
Reading packed data functions
Writing packed data functions
Other functions
$readmemb
$readmemh
$writememb
$writememh
$root
$unit
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System Tasks and Functions Specific to the Tool
The following system tasks and functions are specific to ModelSim. They are not included in the IEEE Std 1364, nor are they likely supported in other simulators. Their use may limit the portability of your code.
$init_signal_driver
The $init_signal_driver() system task drives the value of a VHDL signal or Verilog net onto an existing VHDL signal or Verilog net. This allows you to drive signals or nets at any level of the design hierarchy from within a Verilog module (e.g., a testbench). See
for complete details.
$init_signal_spy
The $init_signal_spy() system task mirrors the value of a VHDL signal or Verilog register/net onto an existing Verilog register or VHDL signal. This system task allows you to reference signals, registers, or nets at any level of hierarchy from within a Verilog module (e.g., a testbench). See
$init_signal_spy for complete details.
$psprintf()
The $psprintf() system function behaves like the $sformat() file I/O task except that the string result is passed back to the user as the function return value for $psprintf(), not placed in the first argument as for $sformat(). Thus $psprintf() can be used where a string is valid. Note that at this time, unlike other system tasks and functions, $psprintf() cannot be overridden by a user-defined system function in the PLI.
$signal_force
The $signal_force() system task forces the value specified onto an existing VHDL signal or Verilog register or net. This allows you to force signals, registers, or nets at any level of the design hierarchy from within a Verilog module (e.g., a testbench). A
$signal_force works the same as the force command with the exception that you cannot issue a repeating force. See
for complete details.
$signal_release
The $signal_release() system task releases a value that had previously been forced onto an existing VHDL signal or Verilog register or net. A $signal_release works the same as the noforce command. See
$signal_release for complete details.
$sdf_done
This task is a "cleanup" function that removes internal buffers, called MIPDs, that have a delay value of zero. These MIPDs are inserted in response to the -v2k_int_delay argument to the vsim command. In general the simulator will automatically remove all zero delay MIPDs. However, if you have $sdf_annotate() calls in your design that are not getting executed, the zero-delay MIPDs are not removed. Adding the $sdf_done task after your last $sdf_annotate() will remove any zero-delay MIPDs that have been created.
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Verilog-XL Compatible System Tasks and Functions
ModelSim supports a number of Verilog-XL specific system tasks and functions.
Supported Tasks and Functions Mentioned in IEEE Std 1364
The following supported system tasks and functions, though not part of the IEEE standard, are described in an annex of the IEEE Std 1364.
$countdrivers
$getpattern
$sreadmemb
$sreadmemh
Supported Tasks not Described in the IEEE Std 1364
The following system tasks are also provided for compatibility with Verilog-XL, though they are not described in the IEEE Std 1364.
$deposit(variable, value);
This system task sets a Verilog register or net to the specified value. variable is the register or net to be changed; value is the new value for the register or net. The value remains until there is a subsequent driver transaction or another $deposit task for the same register or net. This system task operates identically to the ModelSim
force -deposit command.
$disable_warnings("<keyword>"[,<module_instance>...]);
This system task instructs ModelSim to disable warnings about timing check violations or triregs that acquire a value of ‘X’ due to charge decay. <keyword> may be decay or
timing. You can specify one or more module instance names. If you don’t specify a module instance, ModelSim disables warnings for the entire simulation.
$enable_warnings("<keyword>"[,<module_instance>...]);
This system task enables warnings about timing check violations or triregs that acquire a value of ‘X’ due to charge decay. <keyword> may be decay or timing. You can specify one or more module instance names. If you don’t specify a module_instance, ModelSim enables warnings for the entire simulation.
$system("command");
This system function takes a literal string argument, executes the specified operating system command, and displays the status of the underlying OS process. Double quotes are required for the OS command. For example, to list the contents of the working directory on Unix:
$system("ls -l");
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Return value of the $system function is a 32-bit integer that is set to the exit status code of the underlying OS process.
Note
There is a known issue in the return value of this system function on the win32 platform.
If the OS command is built with a cygwin compiler, the exit status code may not be reported correctly when an exception is thrown, and thus the return code may be wrong.
The workaround is to avoid building the application using cygwin or to use the switch
-mno-cygwin in cygwin the gcc command line.
$systemf(list_of_args)
This system function can take any number of arguments. The list_of_args is treated exactly the same as with the $display() function. The OS command that will be run is the final output from $display() given the same list_of_args. Return value of the $systemf function is a 32-bit integer that is set to the exit status code of the underlying OS process.
Note
There is a known issue in the return value of this system function on the win32 platform.
If the OS command is built with a cygwin compiler, the exit status code may not be reported correctly when an exception is thrown, and thus the return code may be wrong.
The workaround is to avoid building the application using cygwin or to use the switch
-mno-cygwin in cygwin the gcc command line.
Supported Tasks that Have Been Extended
The following system tasks are extended to provide additional functionality for negative timing constraints and an alternate method of conditioning, as in Verilog-XL.
$recovery(reference event, data_event, removal_limit, recovery_limit, [notifier],
[tstamp_cond], [tcheck_cond], [delayed_reference], [delayed_data])
The $recovery system task normally takes a recovery_limit as the third argument and an optional notifier as the fourth argument. By specifying a limit for both the third and fourth arguments, the $recovery timing check is transformed into a combination removal and recovery timing check similar to the $recrem timing check. The only difference is that the removal_limit and recovery_limit are swapped.
$setuphold(clk_event, data_event, setup_limit, hold_limit, [notifier], [tstamp_cond],
[tcheck_cond], [delayed_clk], [delayed_data])
The tstamp_cond argument conditions the data_event for the setup check and the clk_event for the hold check. This alternate method of conditioning precludes specifying conditions in the clk_event and data_event arguments.
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The tcheck_cond argument conditions the data_event for the hold check and the clk_event for the setup check. This alternate method of conditioning precludes specifying conditions in the clk_event and data_event arguments.
The delayed_clk argument is a net that is continuously assigned the value of the net specified in the clk_event. The delay is non-zero if the setup_limit is negative, zero otherwise.
The delayed_data argument is a net that is continuously assigned the value of the net specified in the data_event. The delay is non-zero if the hold_limit is negative, zero otherwise.
The delayed_clk and delayed_data arguments are provided to ease the modeling of devices that may have negative timing constraints. The model's logic should reference the delayed_clk and delayed_data nets in place of the normal clk and data nets. This ensures that the correct data is latched in the presence of negative constraints. The simulator automatically calculates the delays for delayed_clk and delayed_data such that the correct data is latched as long as a timing constraint has not been violated. See
Negative Timing Check Limits for more details.
Unsupported Verilog-XL System Tasks
The following system tasks are Verilog-XL system tasks that are not implemented in ModelSim
Verilog, but have equivalent simulator commands.
$input("filename")
This system task reads commands from the specified filename. The equivalent simulator command is do <filename>.
$list[(hierarchical_name)]
This system task lists the source code for the specified scope. The equivalent functionality is provided by selecting a module in the structure pane of the Workspace.
The corresponding source code is displayed in a Source window.
$reset
This system task resets the simulation back to its time 0 state. The equivalent simulator command is restart.
$restart("filename")
This system task sets the simulation to the state specified by filename, saved in a previous call to $save. The equivalent simulator command is restore <filename>.
$save("filename")
This system task saves the current simulation state to the file specified by filename. The equivalent simulator command is checkpoint <filename>.
$scope(hierarchical_name)
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This system task sets the interactive scope to the scope specified by hierarchical_name.
The equivalent simulator command is environment <pathname>.
$showscopes
This system task displays a list of scopes defined in the current interactive scope. The equivalent simulator command is show.
$showvars
This system task displays a list of registers and nets defined in the current interactive scope. The equivalent simulator command is show.
Compiler Directives
ModelSim Verilog supports all of the compiler directives defined in the IEEE Std 1364, some
Verilog-XL compiler directives, and some that are proprietary. The SystemVerilog IEEE Std
P1800-2005 version of the ‘define and ‘include compiler directives are not currently supported.
Many of the compiler directives (such as `timescale) take effect at the point they are defined in the source code and stay in effect until the directive is redefined or until it is reset to its default by a `resetall directive. The effect of compiler directives spans source files, so the order of source files on the compilation command line could be significant. For example, if you have a file that defines some common macros for the entire design, then you might need to place it first in the list of files to be compiled.
The `resetall directive affects only the following directives by resetting them back to their default settings (this information is not provided in the IEEE Std 1364):
`celldefine
‘default_decay_time
`default_nettype
`delay_mode_distributed
`delay_mode_path
`delay_mode_unit
`delay_mode_zero
`protected
`timescale
`unconnected_drive
`uselib
ModelSim Verilog implicitly defines the following macro:
`define MODEL_TECH
IEEE Std 1364 Compiler Directives
The following compiler directives are described in detail in the IEEE Std 1364.
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`celldefine
`default_nettype
`define
`else
`elsif
`endcelldefine
`endif
`ifdef
‘ifndef
`include
‘line
`nounconnected_drive
`resetall
`timescale
`unconnected_drive
`undef
Verilog-XL Compatible Compiler Directives
The following compiler directives are provided for compatibility with Verilog-XL.
‘default_decay_time <time>
This directive specifies the default decay time to be used in trireg net declarations that do not explicitly declare a decay time. The decay time can be expressed as a real or integer number, or as "infinite" to specify that the charge never decays.
`delay_mode_distributed
This directive disables path delays in favor of distributed delays. See
details.
`delay_mode_path
This directive sets distributed delays to zero in favor of path delays. See
for details.
`delay_mode_unit
This directive sets path delays to zero and non-zero distributed delays to one time unit.
See
`delay_mode_zero
This directive sets path delays and distributed delays to zero. See
details.
`uselib
This directive is an alternative to the -v, -y, and +libext source library compiler arguments. See
Verilog-XL uselib Compiler Directive for details.
The following Verilog-XL compiler directives are silently ignored by ModelSim Verilog. Many of these directives are irrelevant to ModelSim Verilog, but may appear in code being ported from Verilog-XL.
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`accelerate
`autoexpand_vectornets
`disable_portfaults
`enable_portfaults
`expand_vectornets
`noaccelerate
`noexpand_vectornets
`noremove_gatenames
`noremove_netnames
`nosuppress_faults
`remove_gatenames
`remove_netnames
`suppress_faults
The following Verilog-XL compiler directives produce warning messages in ModelSim
Verilog. These are not implemented in ModelSim Verilog, and any code containing these directives may behave differently in ModelSim Verilog than in Verilog-XL.
`default_trireg_strength
`signed
`unsigned
Verilog PLI/VPI and SystemVerilog DPI
ModelSim supports the use of the Verilog PLI (Programming Language Interface) and VPI
(Verilog Procedural Interface) and the SystemVerilog DPI (Direct Programming Interface).
These three interfaces provide a mechanism for defining tasks and functions that communicate with the simulator through a C procedural interface. For more information on the ModelSim implementation, see
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Chapter 7
WLF Files (Datasets) and Virtuals
This chapter describes the Wave Log Format (WLF) file and how you should and can use it in your simulation flow.
A ModelSim simulation can be saved to a wave log format (WLF) file for future viewing or comparison to a current simulation. We use the term "dataset" to refer to a WLF file that has been reopened for viewing.
You can open more than one WLF file for simultaneous viewing. You can also create virtual signals that are simple logical combinations of, or logical functions of, signals from different datasets.
WLF files are recordings of simulation runs. The WLF file is written as an archive file in binary format and is used to drive the debug windows at a later time. The files contain data from logged objects (e.g., signals and variables) and the design hierarchy in which the logged objects are found. You can record the entire design or choose specific objects.
The WLF file provides you with precise in-simulation and post-simulation debugging capability. Any number of WLF files can be reloaded for viewing or comparing to the active simulation.
A dataset is a previously recorded simulation that has been loaded into ModelSim. Each dataset has a logical name to let you indicate the dataset to which any command applies. This logical name is displayed as a prefix. The current, active simulation is prefixed by "sim:", while any other datasets are prefixed by the name of the WLF file by default.
Two datasets are displayed in the Wave window in
. The current simulation is shown in the top pane and is indicated by the "sim" prefix. A dataset from a previous simulation is shown in the bottom pane and is indicated by the "gold" prefix.
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Saving a Simulation to a WLF File
Figure 7-1. Displaying Two Datasets in the Wave Window
The simulator resolution (see
Simulator Resolution Limit (Verilog) or
Limit (VHDL) ) must be the same for all datasets you are comparing, including the current
simulation. If you have a WLF file that is in a different resolution, you can use the wlfman command to change it.
Saving a Simulation to a WLF File
If you add objects to the Dataflow, List, or Wave windows, or log objects with the log command, the results of each simulation run are automatically saved to a WLF file called
vsim.wlf in the current directory. If you then run a new simulation in the same directory, the
vsim.wlf file is overwritten with the new results.
If you want to save the WLF file and not have it be overwritten, select the dataset tab in the
Workspace and then select File > Save. Or, you can use the -wlf <filename> argument to the vsim command or the dataset save command.
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Note
If you do not use dataset save or dataset snapshot, you must end a simulation session with a quit or quit -sim command in order to produce a valid WLF file. If you don’t end the simulation in this manner, the WLF file will not close properly, and ModelSim may issue the error message "bad magic number" when you try to open an incomplete dataset in subsequent sessions. If you end up with a "damaged" WLF file, you can try to "repair" it using the wlfrecover command.
WLF File Parameter Overview
There are a number of WLF file parameters that you can control via the modelsim.ini file or a simulator argument. This section summarizes the various parameters.
Feature
WLF Filename
WLF Size Limit
WLF Time Limit
Table 7-1. WLF File Parameters vsim argument
-wlf <filename>
-wlfslim <n>
-wlftlim <t>
modelsim.ini
WLFFilename=<filename>
vsim.wlf
WLFSizeLimit = <n>
WLFTimeLimit = <t>
Default
no limit no limit
WLF Compression -wlfcompress
-wlfnocompress
WLFCompress = 0|1 1 (-wlfcompress)
WLF Optimization
1
-wlfopt
-wlfnoopt
WLFOptimize = 0|1 1 (-wlfopt)
WLF Delete on Quit a
-wlfdeleteonquit
-wlfnodeleteonquit
WLFDeleteOnQuit = 0|1 0
WLF Cache Size a
WLF Collapse Mode
-wlfcachesize <n> WLFCacheSize = <n>
-wlfnocollapse
-wlfcollapsedelta
-wlfcollapsetime
256
WLFCollapseModel = 0|1|2 1
1. These parameters can also be set using the dataset config command.
•
WLF Filename — Specify the name of the WLF file.
•
WLF Size Limit — Limit the size of a WLF file to <n> megabytes by truncating from the front of the file as necessary.
•
WLF Time Limit — Limit the size of a WLF file to <t> time by truncating from the front of the file as necessary.
•
WLF Compression — Compress the data in the WLF file.
•
WLF Optimization — Write additional data to the WLF file to improve draw performance at large zoom ranges. Optimization results in approximately 15% larger
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WLF files. Disabling WLF optimization also prevents ModelSim from reading a previously generated WLF file that contains optimized data.
•
WLF Delete on Quit — Delete the WLF file automatically when the simulation exits.
Valid for current simulation dataset (vsim.wlf) only.
•
WLF Cache Size — Specify the size in megabytes of the WLF reader cache. WLF reader cache is enabled by default. The default value is 256. This feature caches blocks of the WLF file to reduce redundant file I/O. If the cache is made smaller or disabled, least recently used data will be freed to reduce the cache to the specified size.
•
WLF Collapse Mode —WLF event collapsing has three settings: disabled, delta, time: o
When disabled, all events and event order are preserved.
o o
Delta mode records an object's value at the end of a simulation delta (iteration) only.
Default.
Time mode records an object's value at the end of a simulation time step only.
Opening Datasets
To open a dataset, do one of the following:
•
Select File > Open and choose Log Files or use the dataset open command.
Figure 7-2. Open Dataset Dialog Box
The Open Dataset dialog includes the following options:
•
Dataset Pathname — Identifies the path and filename of the WLF file you want to open.
•
Logical Name for Dataset — This is the name by which the dataset will be referred. By default this is the name of the WLF file.
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Viewing Dataset Structure
Viewing Dataset Structure
Each dataset you open creates a structure tab in the Main window workspace. The tab is labeled with the name of the dataset and displays a hierarchy of the design units in that dataset.
The graphic below shows three structure tabs: one for the active simulation (sim) and one each for two datasets (test and gold).
Figure 7-3. Structure Tabs in Workspace Pane
Click here to scroll tabs
If you have too many tabs to display in the available space, you can scroll the tabs left or right by clicking the arrow icons at the bottom right-hand corner of the window.
Structure Tab Columns
Each structure tab displays three columns by default:
Column name
Instance
Design unit
Table 7-2. Structure Tab Columns
Description
the name of the instance the name of the design unit
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Table 7-2. Structure Tab Columns (cont.)
Column name
Design unit type
Description
the type (e.g., Module, Entity, etc.) of the design unit
You can hide or show columns by right-clicking a column name and selecting the name on the list.
Managing Multiple Datasets
GUI
When you have one or more datasets open, you can manage them using the Dataset Browser.
To open the browser, select File > Datasets.
Figure 7-4. The Dataset Browser
Command Line
You can open multiple datasets when the simulator is invoked by specifying more than one
vsim -view <filename> option. By default the dataset prefix will be the filename of the WLF file. You can specify a different dataset name as an optional qualifier to the vsim -view switch on the command line using the following syntax:
-view <dataset>=<filename>
For example:
vsim -view foo=vsim.wlf
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ModelSim designates one of the datasets to be the "active" dataset, and refers all names without dataset prefixes to that dataset. The active dataset is displayed in the context path at the bottom of the Main window. When you select a design unit in a dataset’s structure tab, that dataset becomes active automatically. Alternatively, you can use the Dataset Browser or the environment command to change the active dataset.
Design regions and signal names can be fully specified over multiple WLF files by using the dataset name as a prefix in the path. For example:
sim:/top/alu/out view:/top/alu/out golden:.top.alu.out
Dataset prefixes are not required unless more than one dataset is open, and you want to refer to something outside the active dataset. When more than one dataset is open, ModelSim will automatically prefix names in the Wave and List windows with the dataset name. You can change this default by selecting Tools > Window Preferences (Wave and List windows).
ModelSim also remembers a "current context" within each open dataset. You can toggle between the current context of each dataset using the environment command, specifying the dataset without a path. For example:
env foo:
sets the active dataset to foo and the current context to the context last specified for foo. The context is then applied to any unlocked windows.
The current context of the current dataset (usually referred to as just "current context") is used for finding objects specified without a path.
The Objects pane can be locked to a specific context of a dataset. Being locked to a dataset means that the pane will update only when the content of that dataset changes. If locked to both a dataset and a context (e.g., test: /top/foo), the pane will update only when that specific context changes. You specify the dataset to which the pane is locked by selecting File > Environment.
Restricting the Dataset Prefix Display
The default for dataset prefix viewing is set with a variable in pref.tcl,
PrefMain(DisplayDatasetPrefix). Setting the variable to 1 will display the prefix, setting it to
0 will not. It is set to 1 by default. Either edit the pref.tcl file directly or use the Tools > Edit
Preferences command to change the variable value.
Additionally, you can restrict display of the dataset prefix if you use the environment
-nodataset command to view a dataset. To display the prefix use the environment command with the -dataset option (you won’t need to specify this option if the variable noted above is set to 1). The environment command line switches override the pref.tcl variable.
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Saving at Intervals with Dataset Snapshot
Saving at Intervals with Dataset Snapshot
Dataset Snapshot lets you periodically copy data from the current simulation WLF file to another file. This is useful for taking periodic "snapshots" of your simulation or for clearing the current simulation WLF file based on size or elapsed time.
Once you have logged the appropriate objects, select Tools > Dataset Snapshot (Wave window).
Figure 7-5. Dataset Snapshot Dialog
Collapsing Time and Delta Steps
By default ModelSim collapses delta steps. This means each logged signal that has events during a simulation delta has its final value recorded to the WLF file when the delta has expired.
The event order in the WLF file matches the order of the first events of each signal.
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Virtual Objects
You can configure how ModelSim collapses time and delta steps using arguments to the vsim command or by setting the
WLFCollapseMode variable in the modelsim.ini file. The table
below summarizes the arguments and how they affect event recording.
Table 7-3. vsim Arguments for Collapsing Time and Delta Steps vsim argument effect modelsim.ini setting
WLFCollapseMode = 0 -wlfnocollapse All events for each logged signal are recorded to the WLF file in the exact order they occur in the simulation.
-wlfdeltacollapse Each logged signal which has events during a simulation delta has its final value recorded to the WLF file when the delta has expired.
Default.
-wlftimecollapse Same as delta collapsing but at the timestep granularity.
WLFCollapseMode = 1
WLFCollapseMode = 2
When a run completes that includes single stepping or hitting a breakpoint, all events are flushed to the WLF file regardless of the time collapse mode. It’s possible that single stepping through part of a simulation may yield a slightly different WLF file than just running over that piece of code. If particular detail is required in debugging, you should disable time collapsing.
Virtual Objects
Virtual objects are signal-like or region-like objects created in the GUI that do not exist in the
ModelSim simulation kernel. ModelSim supports the following kinds of virtual objects:
•
•
•
•
Virtual objects are indicated by an orange diamond as illustrated by bus in
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Virtual Objects
Figure 7-6. Virtual Objects Indicated by Orange Diamond
Virtual Signals
Virtual signals are aliases for combinations or subelements of signals written to the WLF file by the simulation kernel. They can be displayed in the Objects, List, and Wave windows, accessed by the examine command, and set using the force command. You can create virtual signals using the Tools > Combine Signals (Wave and List windows) menu selections or by using the virtual signal command. Once created, virtual signals can be dragged and dropped from the
Objects pane to the Wave and List windows.
Virtual signals are automatically attached to the design region in the hierarchy that corresponds to the nearest common ancestor of all the elements of the virtual signal. The virtual signal command has an -install <region> option to specify where the virtual signal should be installed. This can be used to install the virtual signal in a user-defined region in order to reconstruct the original RTL hierarchy when simulating and driving a post-synthesis, gate-level implementation.
A virtual signal can be used to reconstruct RTL-level design buses that were broken down during synthesis. The virtual hide command can be used to hide the display of the broken-down bits if you don't want them cluttering up the Objects pane.
If the virtual signal has elements from more than one WLF file, it will be automatically installed in the virtual region virtuals:/Signals.
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Virtual Objects
Virtual signals are not hierarchical – if two virtual signals are concatenated to become a third virtual signal, the resulting virtual signal will be a concatenation of all the scalar elements of the first two virtual signals.
The definitions of virtuals can be saved to a macro file using the virtual save command. By default, when quitting, ModelSim will append any newly-created virtuals (that have not been saved) to the virtuals.do file in the local directory.
If you have virtual signals displayed in the Wave or List window when you save the Wave or
List format, you will need to execute the virtuals.do file (or some other equivalent) to restore the virtual signal definitions before you re-load the Wave or List format during a later run.
There is one exception: "implicit virtuals" are automatically saved with the Wave or List format.
Implicit and Explicit Virtuals
An implicit virtual is a virtual signal that was automatically created by ModelSim without your knowledge and without you providing a name for it. An example would be if you expand a bus in the Wave window, then drag one bit out of the bus to display it separately. That action creates a one-bit virtual signal whose definition is stored in a special location, and is not visible in the
Objects pane or to the normal virtual commands.
All other virtual signals are considered "explicit virtuals".
Virtual Functions
Virtual functions behave in the GUI like signals but are not aliases of combinations or elements of signals logged by the kernel. They consist of logical operations on logged signals and can be dependent on simulation time. They can be displayed in the Objects, Wave, and List windows and accessed by the examine command, but cannot be set by the force command.
Examples of virtual functions include the following:
• a function defined as the inverse of a given signal
• a function defined as the exclusive-OR of two signals
• a function defined as a repetitive clock
• a function defined as "the rising edge of CLK delayed by 1.34 ns"
Virtual functions can also be used to convert signal types and map signal values.
The result type of a virtual function can be any of the types supported in the GUI expression syntax: integer, real, boolean, std_logic, std_logic_vector, and arrays and records of these types.
Verilog types are converted to VHDL 9-state std_logic equivalents and Verilog net strengths are ignored.
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Virtual Objects
Virtual functions can be created using the virtual function command.
Virtual functions are also implicitly created by ModelSim when referencing bit-selects or partselects of Verilog registers in the GUI, or when expanding Verilog registers in the Objects,
Wave, or List window. This is necessary because referencing Verilog register elements requires an intermediate step of shifting and masking of the Verilog "vreg" data structure.
Virtual Regions
User-defined design hierarchy regions can be defined and attached to any existing design region or to the virtuals context tree. They can be used to reconstruct the RTL hierarchy in a gate-level design and to locate virtual signals. Thus, virtual signals and virtual regions can be used in a gate-level design to allow you to use the RTL test bench.
Virtual regions are created and attached using the virtual region command.
Virtual Types
User-defined enumerated types can be defined in order to display signal bit sequences as meaningful alphanumeric names. The virtual type is then used in a type conversion expression to convert a signal to values of the new type. When the converted signal is displayed in any of the windows, the value will be displayed as the enumeration string corresponding to the value of the original signal.
Virtual types are created using the virtual type command.
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Chapter 8
Waveform Analysis
When your simulation finishes, you will often want to analyze waveforms to assess and debug your design. Designers typically use the Wave window for waveform analysis. However, you can also look at waveform data in a textual format in the List window.
To analyze waveforms in ModelSim, follow these steps:
1. Compile your files.
2. Load your design.
3. Add objects to the Wave or List window.
add wave <object_name> add list <object_name>
4. Run the design.
Objects You Can View
The list below identifies the types of objects can be viewed in the Wave or List window.
•
VHDL objects — (indicated by dark blue diamond in the Wave window) signals, aliases, process variables, and shared variables
•
Verilog objects — (indicated by light blue diamond in the Wave window) nets, registers, variables, and named events
•
Virtual objects — (indicated by an orange diamond in the Wave window) virtual signals, buses, and functions, see;
Virtual Objects for more information
Wave Window Overview
The Wave window opens by default in the MDI frame of the Main window as shown below.
The window can be undocked from the main window by pressing the Undock button in the window header or by using the view -undock wave command. The preference variable
PrefMain(ViewUnDocked) wave can be used to control this default behavior. Setting this variable will open the Wave Window undocked each time you start ModelSim.
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Wave Window Overview
Figure 8-1. Undocking the Wave Window
Here is an example of a Wave window that is undocked from the MDI frame. All menus and icons associated with Wave window functions now appear in the menu and toolbar areas of the
Wave window.
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Figure 8-2. Docking the Wave Window
Waveform Analysis
Wave Window Overview
If the Wave window is docked into the Main window MDI frame, all menus and icons that were in the standalone version of the Wave window move into the Main window menu bar and toolbar.
The Wave window is divided into a number of window panes. All window panes in the Wave window can be resized by clicking and dragging the bar between any two panes.
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List Window Overview
Figure 8-3. Panes in the Wave Window
List Window Overview
The List window displays simulation results in tabular format. Common tasks that people use the window for include:
•
Using gating expressions and trigger settings to focus in on particular signals or events.
See
Configuring New Line Triggering in the List Window .
•
Debugging delta delay issues. See
Delta Delays for more information.
The window is divided into two adjustable panes, which allows you to scroll horizontally through the listing on the right, while keeping time and delta visible on the left.
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Adding Objects to the Wave or List Window
Figure 8-4. Tabular Format of the List Window
Adding Objects to the Wave or List Window
You can add objects to the Wave or List window in several ways.
Adding Objects with Drag and Drop
You can drag and drop objects into the Wave or List window from the Workspace, Active
Processes, Memory, Objects, Source, or Locals panes. You can also drag objects from the Wave window to the List window and vice versa.
Select the objects in the first window, then drop them into the Wave window. Depending on what you select, all objects or any portion of the design can be added.
Adding Objects with a Menu Command
The Add menu in the Main windows let you add objects to the Wave window, List window, or
Log file.
Adding Objects with a Command
Use the add list or add wave commands to add objects from the command line. For example:
VSIM> add wave /proc/a
Adds signal /proc/a to the Wave window.
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VSIM> add list *
Adds all the objects in the current region to the List window.
VSIM> add wave -r /*
Adds all objects in the design to the Wave window.
Adding Objects with a Window Format File
Select File > Open > Format and specify a previously saved format file. See
Window Format for details on how to create a format file.
Measuring Time with Cursors in the Wave
Window
ModelSim uses cursors to measure time in the Wave window. Cursors extend a vertical line over the waveform display and identify a specific simulation time. Multiple cursors can be used to measure time intervals, as shown in the graphic below.
When the Wave window is first drawn, there is one cursor located at time zero. Clicking anywhere in the waveform display brings that cursor to the mouse location. The selected cursor is drawn as a bold solid line; all other cursors are drawn with thin lines.
As shown in the graphic below, three window panes relate to cursors: the cursor name pane on the bottom left, the cursor value pane in the bottom middle, and the cursor pane with horizontal
"tracks" on the bottom right.
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Measuring Time with Cursors in the Wave Window
Figure 8-5. Cursor Names, Values and Time Measurements
Working with Cursors
The table below summarizes common cursor actions.
Action
Add cursor
Table 8-1. Actions for Cursors
Menu command
(Wave window docked)
Menu command
(Wave window undocked)
Add > Wave > Cursor Add > Cursor
Toolbar button
Delete cursor
Wave > Delete Cursor Edit > Delete Cursor
Zoom In on
Active Cursor
Wave > Zoom > Zoom
Cursor
View > Zoom > Zoom
Cursor
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Action
Lock cursor
Name cursor
Select cursor
Table 8-1. Actions for Cursors (cont.)
Menu command
(Wave window docked)
Menu command
(Wave window undocked)
Wave > Edit Cursor Edit > Edit Cursor
Wave > Edit Cursor Edit > Edit Cursor
Wave > Cursors View > Cursors
Toolbar button
NA
NA
NA
Shortcuts for Working with Cursors
There are a number of useful keyboard and mouse shortcuts related to the actions listed above:
•
Select a cursor by clicking the cursor name.
•
Jump to a "hidden" cursor (one that is out of view) by double-clicking the cursor name.
•
Name a cursor by right-clicking the cursor name and entering a new value. Press
<Enter> on your keyboard after you have typed the new name.
•
Move a locked cursor by holding down the <shift> key and then clicking-and-dragging the cursor.
•
Move a cursor to a particular time by right-clicking the cursor value and typing the value to which you want to scroll. Press <Enter> on your keyboard after you have typed the new value.
Understanding Cursor Behavior
The following list describes how cursors "behave" when you click in various panes of the Wave window:
•
If you click in the waveform pane, the cursor closest to the mouse position is selected and then moved to the mouse position.
•
Clicking in a horizontal "track" in the cursor pane selects that cursor and moves it to the mouse position.
•
Cursors "snap" to a waveform edge if you click or drag a cursor along the selected waveform to within ten pixels of a waveform edge. You can set the snap distance in the
Window Preferences dialog. Select Tools > Options > Wave Preferences when the
Wave window is docked in the Main window MDI frame. Select Tools > Window
Preferences when the Wave window is a stand-alone, undocked window.
•
You can position a cursor without snapping by dragging in the cursor pane below the waveforms.
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Setting Time Markers in the List Window
Jumping to a Signal Transition
You can move the active cursor to the next or previous transition on the selected signal using these two buttons on the toolbar:
Find Previous
Transition
locate the previous signal value change for the selected signal
Find Next Transition
locate the next signal value change for the selected signal
Setting Time Markers in the List Window
Time markers in the List window are similar to cursors in the Wave window. Time markers tag lines in the data table so you can quickly jump back to that time. Markers are indicated by a thin box surrounding the marked line.
Figure 8-6. Time Markers in the List Window
Working with Markers
The table below summarizes actions you can take with markers.
Action
Add marker
Table 8-2. Actions for Time Markers
Method
Select a line and then select Edit > Add Marker
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Zooming the Wave Window Display
Action
Delete marker
Table 8-2. Actions for Time Markers (cont.)
Method
Select a tagged line and then select Edit > Delete
Marker
Goto marker Select View > Goto > <time>
Zooming the Wave Window Display
Zooming lets you change the simulation range in the waveform pane. You can zoom using the context menu, toolbar buttons, mouse, keyboard, or commands.
Zooming with the Menu, Toolbar and Mouse
You can access Zoom commands from the View menu in the Wave window when it is undocked, from the Wave > Zoom menu selections in the Main window when the Wave window is docked, or by clicking the right mouse button in the waveform pane of the Wave window.
These zoom buttons are available on the toolbar:
Zoom In 2x
zoom in by a factor of two from the current view
Zoom In on Active Cursor
centers the active cursor in the waveform display and zooms in
Zoom Mode
change mouse pointer to zoom mode; see below
Zoom Out 2x
zoom out by a factor of two from current view
Zoom Full
zoom out to view the full range of the simulation from time 0 to the current time
To zoom with the mouse, first enter zoom mode by selecting View > Zoom > Mouse Mode >
Zoom Mode. The left mouse button then offers 3 zoom options by clicking and dragging in different directions:
•
Down-Right or Down-Left: Zoom Area (In)
•
Up-Right: Zoom Out
•
Up-Left: Zoom Fit
Also note the following about zooming with the mouse:
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Zooming the Wave Window Display
•
The zoom amount is displayed at the mouse cursor. A zoom operation must be more than 10 pixels to activate.
•
You can enter zoom mode temporarily by holding the <Ctrl> key down while in select mode.
•
With the mouse in the Select Mode, the middle mouse button will perform the above zoom operations.
Saving Zoom Range and Scroll Position with Bookmarks
Bookmarks save a particular zoom range and scroll position. This lets you return easily to a specific view later. You save the bookmark with a name and then access the named bookmark from the Bookmark menu. Bookmarks are saved in the Wave format file (see
Adding Objects with a Window Format File
) and are restored when the format file is read.
Managing Bookmarks
The table below summarizes actions you can take with bookmarks.
Action
Table 8-3. Actions for Bookmarks
Menu commands
(Wave window docked)
Menu commands
(Wave window undocked)
Add > Bookmark
Add bookmark
Add > Wave >
Bookmark
View bookmark
Wave > Bookmarks >
<bookmark_name>
Delete bookmark Wave > Bookmarks >
Bookmarks > <select bookmark then Delete>
View > Bookmarks >
<bookmark_name>
View > Bookmarks >
Bookmarks > <select bookmark then Delete>
Command
bookmark add wave bookmark goto wave bookmark delete wave
Adding Bookmarks
To add a bookmark, follow these steps:
1. Zoom the wave window as you see fit using one of the techniques discussed in
Zooming the Wave Window Display .
2. If the Wave window is docked, select Add > Wave > Bookmark. If the Wave window is undocked, select Add > Bookmark.
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Figure 8-7. Bookmark Properties Dialog
3. Give the bookmark a name and click OK.
Editing Bookmarks
Once a bookmark exists, you can change its properties by selecting Wave > Bookmarks >
Bookmarks if the Wave window is docked; or by selecting Tools > Bookmarks if the Wave window is undocked.
Searching in the Wave and List Windows
The Wave and List windows provide two methods for locating objects:
•
Finding signal names – Select Edit > Find or use the find command to search for the name of a signal.
•
Search for values or transitions – Select Edit > Signal Search to locate transitions or signal values. The search feature is not available in all versions of ModelSim.
Finding Signal Names
The Find command is used to locate a signal name or value in the Wave or List window. When you select Edit > Find, the Find dialog appears.
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Searching in the Wave and List Windows
Figure 8-8. Find Signals by Name or Value
One option of note is the "Exact" checkbox. Check Exact if you only want to find objects that match your search exactly. For example, searching for "clk" without Exact will find /top/clk and clk1.
There are two differences between the Wave and List windows as it relates to the Find feature:
•
In the Wave window you can specify a value to search for in the values pane.
•
The find operation works only within the active pane in the Wave window.
Searching for Values or Transitions
Available in some versions of ModelSim, the Search command lets you search for transitions or values on selected signals. When you select Edit > Search Signals, the Signal Search dialog appears.
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Searching in the Wave and List Windows
Figure 8-9. Wave Signal Search Dialog
One option of note is Search for Expression. The expression can involve more than one signal but is limited to signals currently in the window. Expressions can include constants, variables, and DO files. See Expression Syntax for more information.
Using the Expression Builder for Expression Searches
The Expression Builder is a feature of the Wave and List Signal Search dialog boxes, and the
List trigger properties dialog box. It aids in building a search expression that follows the
GUI_expression_format .
To locate the Builder:
• select Edit > Search Signals (List or Wave window)
• select the Search for Expression option in the resulting dialog box
• select the Builder button
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Figure 8-10. Expression Builder Dialog
The Expression Builder dialog box provides an array of buttons that help you build a GUI expression. For instance, rather than typing in a signal name, you can select the signal in the associated Wave or List window and press Insert Selected Signal. All Expression Builder buttons correspond to the Expression Syntax .
Saving an Expression to a Tcl Variable
Clicking the Save button will save the expression to a Tcl variable. Once saved this variable can be used in place of the expression. For example, say you save an expression to the variable
"foo". Here are some operations you could do with the saved variable:
•
Read the value of foo with the set command:
set foo
•
Put $foo in the Expression: entry box for the Search for Expression selection.
•
Issue a searchlog command using foo:
searchlog -expr $foo 0
Searching for when a Signal Reaches a Particular Value
Select the signal in the Wave window and click Insert Selected Signal and ==. Then, click the value buttons or type a value.
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Formatting the Wave Window
Evaluating Only on Clock Edges
Click the && button to AND this condition with the rest of the expression. Then select the clock in the Wave window and click Insert Selected Signal and ‘rising. You can also select the falling edge or both edges.
Operators
Other buttons will add operators of various kinds (see Expression Syntax ), or you can type them in.
Formatting the Wave Window
Setting Wave Window Display Preferences
You can set Wave Window display preferences by selecting Tools > Options > Wave
Preferences (when the window is docked in the MDI frame) or Tools > Window Preferences
(when the window is undocked). These commands open the Wave Window Preferences dialog
(
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Figure 8-11. Display Tab of the Wave Window Preferences Dialog
Hiding/Showing Path Hierarchy
You can set how many elements of the object path display by changing the Display Signal Path value in the Wave Window Preferences dialog (
Figure 8-11 ). Zero indicates the full path while
a non-zero number indicates the number of path elements to be displayed.
Setting the Timeline to Count Clock Cycles
You can set the timeline of the Wave window to count clock cycles rather than elapsed time. If the Wave window is docked in the MDI frame, open the Wave Window Preferences dialog by selecting Tools > Options > Wave Preferences from the Main window menus. If the Wave window is undocked, select Tools > Window Preferences from the Wave window menus. This opens the Wave Window Preferences dialog. In the dialog, select the Grid & Timeline tab
(
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Formatting the Wave Window
Figure 8-12. Grid & Timeline Tab of Wave Window Preferences Dialog
Enter the period of your clock in the Grid Period field and select “Display grid period count
(cycle count).” The timeline will now show the number of clock cycles, as shown in
Figure 8-13. Clock Cycles in Timeline of Wave Window
Formatting Objects in the Wave Window
You can adjust various object properties to create the view you find most useful. Select one or more objects and then select View > Properties or use the selections in the Format menu.
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Formatting the Wave Window
Changing Radix (base) for the Wave Window
One common adjustment is changing the radix (base) of an object. When you select View >
Properties, the Wave Signal Properties dialog appears.
Figure 8-14. Changing Signal Radix
The default radix is symbolic, which means that for an enumerated type, the value pane lists the actual values of the enumerated type of that object. For the other radixes - binary, octal, decimal, unsigned, hexadecimal, or ASCII - the object value is converted to an appropriate representation in that radix.
Note
When the symbolic radix is chosen for SystemVerilog reg and integer types, the values are treated as binary. When the symbolic radix is chosen for SystemVerilog bit and int types, the values are considered to be decimal.
Aside from the Wave Signal Properties dialog, there are three other ways to change the radix:
•
Change the default radix for the current simulation using Simulate > Runtime Options
(Main window)
•
Change the default radix for the current simulation using the radix command.
•
Change the default radix permanently by editing the
modelsim.ini file.
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Formatting the Wave Window
Dividing the Wave Window
Dividers serve as a visual aid for debugging, allowing you to separate signals and waveforms for easier viewing. In the graphic below, a bus is separated from the two signals above it with a divider called "Bus."
Figure 8-15. Separate Signals with Wave Window Dividers
To insert a divider, follow these steps:
1. Select the signal above which you want to place the divider.
2. If the Wave pane is docked in MDI frame of the Main window, select Add > Wave >
Divider from the Main window menu bar. If the Wave window stands alone, undocked from the Main window, select Add > Divider from the Wave window menu bar.
3. Specify the divider name in the Wave Divider Properties dialog. The default name is
New Divider. Unnamed dividers are permitted. Simply delete "New Divider" in the
Divider Name field to create an unnamed divider.
4. Specify the divider height (default height is 17 pixels) and then click OK.
You can also insert dividers with the -divider argument to the add wave command.
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Formatting the Wave Window
Working with Dividers
The table below summarizes several actions you can take with dividers:
Action
Move a divider
Change a divider’s name or size
Delete a divider
Table 8-4. Actions for Dividers
Method
Click-and-drag the divider to the desired location
Right-click the divider and select Divider Properties
Right-click the divider and select Delete
Splitting Wave Window Panes
The pathnames, values, and waveforms panes of the Wave window display can be split to accommodate signals from one or more datasets. For more information on viewing multiple simulations, see
WLF Files (Datasets) and Virtuals .
To split the window, select Add > Window Pane.
In the illustration below, the top split shows the current active simulation with the prefix "sim," and the bottom split shows a second dataset with the prefix "gold".
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Wave Groups
Figure 8-16. Splitting Wave Window Panes
The Active Split
The active split is denoted with a solid white bar to the left of the signal names. The active split becomes the target for objects added to the Wave window.
Wave Groups
Wave groups are a wave window specific container object for creating arbitrary groups of items. A wave group may contain 0, 1 or many items. The command line as well as drag and drop may be used to add or remove items from a group. Groups themselves may be dragged around the wave window or to another wave window.
Currently, groups may not be nested.
Creating a Wave Group
There are two ways to create a wave group.
1. Use the Tools > Group menu selection.
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Wave Groups
a. Select a set of signals in the wave window.
b. Select the Tools > Group menu item. The Wave Group Create dialog will appear.
Figure 8-17. Fill in the name of the group in the Group Name field.
c. Click Ok. The new wave group will be denoted by a red diamond in the Wave window pathnames.
Figure 8-18. Wave groups denoted by red diamond
2. Use the -group argument to the add wave command.
Example 1 — The following command will create a group named mygroup containing three items: add wave -group mygroup sig1 sig2 sig3
Example 2 — The following command will create an empty group named mygroup: add wave -group mygroup
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Wave Groups
Deleting or Ungrouping a Wave Group
If a wave group is selected and cut or deleted the entire group and all its contents will be removed from the wave window. Likewise, the delete wave command will remove the entire group if the group name is specified.
If a wave group is selected and the Tools > Ungroup menu item is selected the group will be removed and all of its contents will remain in the Wave window in existing order.
Adding Items to an Existing Wave Group
There are three ways to add items to an existing wave group.
1. Using the drag and drop capability to move items outside of the group or from other windows within ModelSim into the group. The insertion indicator will show the position the item will be dropped into the group. If the cursor is moved over the lower portion of the group item name a box will be drawn around the group name indicating the item will be dropped into the last position in the group.
2. The cut/copy/paste functions may be used to paste items into a group.
3. Use the add wave -group command.
The following example adds two more signals to an existing group called mygroup.
add wave -group mygroup sig4 sig5
Removing Items from an Existing Wave Group
You can use any of the following methods to remove an item from a wave group.
1. Use the drag and drop capability to move an item outside of the group.
2. Use menu or icon selections to cut or delete an item or items from the group.
3. Use the delete wave command to specify a signal to be removed from the group.
Note
The delete wave command removes all occurrences of a specified name from the wave window, not just an occurrence within a group.
Miscellaneous Wave Group Features
Dragging a wave group from the Wave window to the List window will result in all of the items within the group being added to the List window.
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Formatting the List Window
Dragging a group from the Wave window to the Transcript window will result in a list of all of the items within the group being added to the existing command line, if any.
Formatting the List Window
Setting List Window Display Properties
Before you add objects to the List window, you can set the window’s display properties. To change when and how a signal is displayed in the List window, select Tools > List Preferences from the List window menu bar (when the window is undocked).
Figure 8-19. Modifying List Window Display Properties
Formatting Objects in the List Window
You can adjust various properties of objects to create the view you find most useful. Select one or more objects and then select View > Signal Properties from the List window menu bar
(when the window is undocked).
Changing Radix (base) for the List Window
One common adjustment is changing the radix (base) of an object. When you select View >
Signal Properties, the List Signal Properties dialog appears (
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Formatting the List Window
Figure 8-20. List Signal Properties Dialog
The default radix is symbolic, which means that for an enumerated type, the window lists the actual values of the enumerated type of that object. For the other radixes - binary, octal, decimal, unsigned, hexadecimal, or ASCII - the object value is converted to an appropriate representation in that radix.
Changing the radix can make it easier to view information in the List window. Compare the image below (with decimal values) with the image in the section
symbolic values).
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Saving the Window Format
Figure 8-21. Changing the Radix in the List Window
Aside from the List Signal Properties dialog, there are three other ways to change the radix:
•
Change the default radix for the current simulation using Simulate > Runtime Options
(Main window)
•
Change the default radix for the current simulation using the radix command.
•
Change the default radix permanently by editing the
modelsim.ini file.
Saving the Window Format
By default all Wave and List window information is forgotten once you close the windows. If you want to restore the windows to a previously configured layout, you must save a window format file. Follow these steps:
1. Add the objects you want to the Wave or List window.
2. Edit and format the objects to create the view you want.
3. Save the format to a file by selecting File > Save > Format.
To use the format file, start with a blank Wave or List window and run the DO file in one of two ways:
•
Invoke the do command from the command line:
VSIM> do <my_format_file>
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Printing and Saving Waveforms in the Wave window
•
Select File > Load.
Note
Window format files are design-specific. Use them only with the design you were simulating when they were created.
Printing and Saving Waveforms in the Wave window
You can print the waveform display or save it as an encapsulated postscript (EPS) file.
Saving a .eps Waveform File and Printing in UNIX
Select File > Print Postscript (Wave window) to print all or part of the waveform in the current
Wave window in UNIX, or save the waveform as a .eps file on any platform (see also the write wave command).
Printing from the Wave Window on Windows Platforms
Select File > Print (Wave window) to print all or part of the waveform in the current Wave window, or save the waveform as a printer file (a Postscript file for Postscript printers).
Printer Page Setup
Select File > Page setup or click the Setup button in the Write Postscript or Print dialog box to define how the printed page will appear.
Saving List Window Data to a File
Select File > Write List in the List window to save the data in one of these formats:
•
Tabular — writes a text file that looks like the window listing ns delta /a /b /cin /sum /cout
0 +0 X X U X U
0 +1 0 1 0 X U
2 +0 0 1 0 X U
•
Events — writes a text file containing transitions during simulation
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@0 +0
/a X
/b X
/cin U
/sum X
/cout U
@0 +1
/a 0
/b 1
/cin 0
•
TSSI — writes a file in standard TSSI format; see also, the write tssi command.
0 00000000000000010?????????
2 00000000000000010???????1?
3 00000000000000010??????010
4 00000000000000010000000010
100 00000001000000010000000010
You can also save List window output using the write list command.
Combining Objects into Buses
You can combine signals in the Wave or List window into buses. A bus is a collection of signals concatenated in a specific order to create a new virtual signal with a specific value. A virtual compare signal (the result of a comparison simulation) is not supported for combination with any other signal.
To combine signals into a bus, use one of the following methods:
•
Select two or more signals in the Wave or List window and then choose Tools >
Combine Signals from the menu bar. A virtual signal that is the result of a comparison simulation is not supported for combining with any other signal.
•
Use the virtual signal command at the Main window command prompt.
In the illustration below, three signals have been combined to form a new bus called "Bus1".
Note that the component signals are listed in the order in which they were selected in the Wave window. Also note that the value of the bus is made up of the values of its component signals, arranged in a specific order.
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Combining Objects into Buses
Figure 8-22. Signals Combined to Create Virtual Bus
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Configuring New Line Triggering in the List Window
Configuring New Line Triggering in the List
Window
New line triggering refers to what events cause a new line of data to be added to the List window. By default ModelSim adds a new line for any signal change including deltas within a single unit of time resolution.
You can set new line triggering on a signal-by-signal basis or for the whole simulation. To set for a single signal, select View > Signal Properties from the List window menu bar (when the window is undocked) and select the Triggers line setting. Individual signal settings override global settings.
Figure 8-23. Line Triggering in the List Window
To modify new line triggering for the whole simulation, select Tools > List Preferences from the List window menu bar (when the window is undocked), or use the configure command.
When you select Tools > List Preferences, the Modify Display Properties dialog appears:
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Configuring New Line Triggering in the List Window
Figure 8-24. Setting Trigger Properties
The following table summaries the triggering options:
Option
Deltas
Strobe trigger
Trigger gating
Table 8-5. Triggering Options
Description
Choose between displaying all deltas (Expand
Deltas), displaying the value at the final delta
(Collapse Delta). You can also hide the delta column all together (No Delta), however this will display the value at the final delta.
Specify an interval at which you want to trigger data display
Use a gating expression to control triggering; see
Using Gating Expressions to Control Triggering
for more details
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Configuring New Line Triggering in the List Window
Using Gating Expressions to Control Triggering
Trigger gating controls the display of data based on an expression. Triggering is enabled once the gating expression evaluates to true. This setup behaves much like a hardware signal analyzer that starts recording data on a specified setup of address bits and clock edges.
Here are some points about gating expressions:
•
Gating expressions affect the display of data but not acquisition of the data.
•
The expression is evaluated when the List window would normally have displayed a row of data (given the other trigger settings).
•
The duration determines for how long triggering stays enabled after the gating expression returns to false (0). The default of 0 duration will enable triggering only while the expression is true (1). The duration is expressed in x number of default timescale units.
•
Gating is level-sensitive rather than edge-triggered.
Trigger Gating Example Using the Expression Builder
This example shows how to create a gating expression with the ModelSim Expression Builder.
Here is the procedure:
1. Select Tools > Window Preferences from the List window menu bar (when the window is undocked) and select the Triggers tab.
2. Click the Use Expression Builder button.
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Figure 8-25. Trigger Gating Using Expression Builder
3. Select the signal in the List window that you want to be the enable signal by clicking on its name in the header area of the List window.
4. Click Insert Selected Signal and then 'rising in the Expression Builder.
5. Click OK to close the Expression Builder.
You should see the name of the signal plus "'rising" added to the Expression entry box of the Modify Display Properties dialog box.
6. Click OK to close the dialog.
If you already have simulation data in the List window, the display should immediately switch to showing only those cycles for which the gating signal is rising. If that isn't quite what you want, you can go back to the expression builder and play with it until you get it the way you want it.
If you want the enable signal to work like a "One-Shot" that would display all values for the next, say 10 ns, after the rising edge of enable, then set the On Duration value to 10 ns.
Trigger Gating Example Using Commands
The following commands show the gating portion of a trigger configuration statement:
configure list -usegating 1 configure list -gateduration 100 configure list -gateexpr {/test_delta/iom_dd'rising}
See the configure command for more details.
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Miscellaneous Tasks
Sampling Signals at a Clock Change
You easily can sample signals at a clock change using the add list command with the
-notrigger argument. The -notrigger argument disables triggering the display on the specified signals. For example:
add list clk -notrigger a b c
When you run the simulation, List window entries for clk, a, b, and c appear only when clk changes.
If you want to display on rising edges only, you have two options:
1. Turn off the List window triggering on the clock signal, and then define a repeating strobe for the List window.
2. Define a "gating expression" for the List window that requires the clock to be in a specified state. See above.
Miscellaneous Tasks
Examining Waveform Values
You can use your mouse to display a dialog that shows the value of a waveform at a particular time. You can do this two ways:
•
Rest your mouse pointer on a waveform. After a short delay, a dialog will pop-up that displays the value for the time at which your mouse pointer is positioned. If you’d prefer that this popup not display, it can be toggled off in the display properties. See
Wave Window Display Preferences .
•
Right-click a waveform and select Examine. A dialog displays the value for the time at which you clicked your mouse. This method works in the List window as well.
Displaying Drivers of the Selected Waveform
You can automatically display in the Dataflow window the drivers of a signal selected in the
Wave window. You can do this three ways:
•
Select a waveform and click the Show Drivers button on the toolbar.
•
Select a waveform and select Show Drivers from the shortcut menu
•
Double-click a waveform edge (you can enable/disable this option in the display properties dialog; see
Setting Wave Window Display Preferences )
This operation opens the Dataflow window and displays the drivers of the signal selected in the
Wave window. The Wave pane in the Dataflow window also opens to show the selected signal
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Creating and managing breakpoints
with a cursor at the selected time. The Dataflow window shows the signal(s) values at the current cursor position.
Sorting a Group of Objects in the Wave Window
Select View > Sort to sort the objects in the pathname and values panes.
Creating and managing breakpoints
ModelSim supports both signal (i.e., when conditions) and file-line breakpoints. Breakpoints can be set from multiple locations in the GUI or from the command line.
Signal breakpoints
Signal breakpoints (when conditions) instruct ModelSim to perform actions when the specified conditions are met. For example, you can break on a signal value or at a specific simulator time
(see the when command for additional details). When a breakpoint is hit, a message in the Main window transcript identifies the signal that caused the breakpoint.
Setting signal breakpoints from the command line
You use the when command to set a signal breakpoint from the VSIM> prompt.
Setting signal breakpoints from the GUI
Signal breakpoints are most easily set in the
Right-click a signal and select Insert Breakpoint from the context menu. A breakpoint is set on that signal and will be listed in the Breakpoints dialog.
File-line breakpoints
File-line breakpoints are set on executable lines in your source files. When the line is hit, the simulator stops and the Source window opens to show the line with the breakpoint. You can change this behavior by editing the PrefSource(OpenOnBreak) variable. See
Preferences for details on setting preference variables.
Setting file-line breakpoints from the command line
You use the bp command to set a file-line breakpoint from the VSIM> prompt.
Setting file-line breakpoints from the GUI
File-line breakpoints are most easily set using your mouse in the
blue line number at the left side of the Source window, and a red diamond denoting a breakpoint
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Creating and managing breakpoints
will appear. The breakpoints are toggles – click once to create the colored diamond; click again to disable or enable the breakpoint. To delete the breakpoint completely, click the red diamond with your right mouse button, and select Remove Breakpoint.
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Chapter 9
Tracing Signals with the Dataflow Window
This chapter discusses how to use the Dataflow window for tracing signal values and browsing the physical connectivity of your design.
Dataflow Window Overview
The Dataflow window allows you to explore the "physical" connectivity of your design.
Note
OEM versions of ModelSim have limited Dataflow functionality. Many of the features described below will operate differently. The window will show only one process and its attached signals or one signal and its attached processes, as displayed in
.
Figure 9-1. The Dataflow Window (undocked)
Objects You Can View in the Dataflow Window
The Dataflow window displays:
• processes
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• signals, nets, and registers
The window has built-in mappings for all Verilog primitive gates (i.e., AND, OR, etc.). For components other than Verilog primitives, you can define a mapping between processes and built-in symbols. See
for details.
Adding Objects to the Window
You can use any of the following methods to add objects to the Dataflow window:
• drag and drop objects from other windows
• use the Navigate menu options in the Dataflow window
• use the add dataflow command
• double-click any waveform in the Wave window display
The Navigate menu offers four commands that will add objects to the window. The commands include:
•
View region — clear the window and display all signals from the current region
•
Add region — display all signals from the current region without first clearing window
•
View all nets — clear the window and display all signals from the entire design
•
Add ports — add port symbols to the port signals in the current region
When you view regions or entire nets, the window initially displays only the drivers of the added objects in order to reduce clutter. You can easily view readers by selecting an object and invoking Navigate > Expand net to readers.
A small circle above an input signal on a block denotes a trigger signal that is on the process’ sensitivity list.
Links to Other Windows
The Dataflow window has links to other windows as described below:
Table 9-1. Dataflow Window Links to Other Windows and Panes
Window Link
select a signal or process in the Dataflow window, and the structure tab updates if that object is in a different design unit select a process in either window, and that process is highlighted in the other
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Table 9-1. Dataflow Window Links to Other Windows and Panes (cont.)
Window
Link
select a design object in either window, and that object is highlighted in the other
• trace through the design in the Dataflow window, and the associated signals are added to the Wave window
• move a cursor in the Wave window, and the values update in the Dataflow window
select an object in the Dataflow window, and the Source window updates if that object is in a different source file
Exploring the Connectivity of the Design
A primary use of the Dataflow window is exploring the "physical" connectivity of your design.
One way of doing this is by expanding the view from process to process. This allows you to see the drivers/receivers of a particular signal, net, or register.
You can expand the view of your design using menu commands or your mouse. To expand with the mouse, simply double click a signal, register, or process. Depending on the specific object you click, the view will expand to show the driving process and interconnect, the reading process and interconnect, or both.
Alternatively, you can select a signal, register, or net, and use one of the toolbar buttons or menu commands described in
Table 9-2. Icon and Menu Selections for Exploring Design Connectivity
Expand net to all drivers
display driver(s) of the selected signal, net, or register
Navigate > Expand net to drivers
Navigate > Expand net
Expand net to all drivers and readers
display driver(s) and reader(s) of the selected signal, net, or register
Expand net to all readers
display reader(s) of the selected signal, net, or register
Navigate > Expand net to readers
As you expand the view, note that the "layout" of the design may adjust to best show the connectivity. For example, the location of an input signal may shift from the bottom to the top of a process.
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The Embedded Wave Viewer
Tracking Your Path Through the Design
You can quickly traverse through many components in your design. To help mark your path, the objects that you have expanded are highlighted in green.
Figure 9-2. Green Highlighting Shows Your Path Through the Design
You can clear this highlighting using the Edit > Erase highlight command or by clicking the Erase highlight icon in the toolbar.
The Embedded Wave Viewer
Another way of exploring your design is to use the Dataflow window’s embedded wave viewer.
This viewer closely resembles, in appearance and operation, the stand-alone Wave window (see
Waveform Analysis for more information).
The wave viewer is opened using the View > Show Wave command or by clicking the
Show Wave icon.
One common scenario is to place signals in the wave viewer and the Dataflow panes, run the design for some amount of time, and then use time cursors to investigate value changes. In other words, as you place and move cursors in the wave viewer pane (see
Cursors in the Wave Window for details), the signal values update in the Dataflow pane.
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Zooming and Panning
Figure 9-3. Wave Viewer Displays Inputs and Outputs of Selected Process
Another scenario is to select a process in the Dataflow pane, which automatically adds to the wave viewer pane all signals attached to the process.
See
Tracing Events (Causality) for another example of using the embedded wave viewer.
Zooming and Panning
The Dataflow window offers several tools for zooming and panning the display.
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These zoom buttons are available on the toolbar:
Zoom In
zoom in by a factor of two from the current view
Zoom Out
zoom out by a factor of two from current view
Zoom Full
zoom out to view the entire schematic
To zoom with the mouse, you can either use the middle mouse button or enter Zoom Mode by selecting View > Zoom and then use the left mouse button.
Four zoom options are possible by clicking and dragging in different directions:
•
Down-Right: Zoom Area (In)
•
Up-Right: Zoom Out (zoom amount is displayed at the mouse cursor)
•
Down-Left: Zoom Selected
•
Up-Left: Zoom Full
The zoom amount is displayed at the mouse cursor. A zoom operation must be more than 10 pixels to activate.
Panning with the Mouse
You can pan with the mouse in two ways: 1) enter Pan Mode by selecting View > Pan and then drag with the left mouse button to move the design; 2) hold down the <Ctrl> key and drag with the middle mouse button to move the design.
Tracing Events (Causality)
One of the most useful features of the Dataflow window is tracing an event to see the cause of an unexpected output. This feature uses the Dataflow window’s embedded wave viewer (see
The Embedded Wave Viewer for more details).
In short you identify an output of interest in the Dataflow pane and then use time cursors in the wave viewer pane to identify events that contribute to the output.
The process for tracing events is as follows:
1. Log all signals before starting the simulation (add log -r /*).
2. After running a simulation for some period of time, open the Dataflow window and the wave viewer pane.
3. Add a process or signal of interest into the Dataflow window (if adding a signal, find its driving process). Select the process and all signals attached to the selected process will appear in the wave viewer pane.
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4. Place a time cursor on an edge of interest; the edge should be on a signal that is an output of the process.
5. Select Trace > Trace input net to event.
A second cursor is added at the most recent input event.
6. Keep selecting Trace > Trace next event until you've reached an input event of interest. Note that the signals with the events are selected in the wave pane.
7. Now select Trace > Trace Set.
The Dataflow display "jumps" to the source of the selected input event(s). The operation follows all signals selected in the wave viewer pane. You can change which signals are followed by changing the selection.
8. To continue tracing, go back to step 5 and repeat.
If you want to start over at the originally selected output, select Trace > Trace event reset.
Tracing the Source of an Unknown State (StX)
Another useful Dataflow window debugging tool is the ability to trace an unknown state (StX) back to its source. Unknown values are indicated by red lines in the Wave window (
and in the wave viewer of the Dataflow window.
Figure 9-4. Unknown States Shown as Red Lines in Wave Window
The procedure for tracing to the source of an unknown state in the Dataflow window is as follows:
1. Load your design.
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2. Log all signals in the design or any signals that may possibly contribute to the unknown value (log -r /* will log all signals in the design).
3. Add signals to the Wave window or wave viewer pane, and run your design the desired length of time.
4. Put a Wave window cursor on the time at which the signal value is unknown (StX). In
Figure 9-4 , Cursor 1 at time 2305 shows an unknown state on signal t_out.
5. Add the signal of interest to the Dataflow window by doing one of the following: o double-clicking on the signal’s waveform in the Wave window, o o right-clicking the signal in the Objects window and selecting Add to Dataflow >
Selected Signals from the popup menu, selecting the signal in the Objects window and selecting Add > Dataflow > Selected
Signals from the menu bar.
6. In the Dataflow window, make sure the signal of interest is selected.
7. Trace to the source of the unknown by doing one of the following: o o
If the Dataflow window is docked, select Tools > Trace > TraceX, Tools > Trace >
TraceX Delay, Tools > Trace > ChaseX, or Tools > Trace > ChaseX Delay.
If the Dataflow window is undocked, select Trace > TraceX, Trace > TraceX
Delay, Trace > ChaseX, or Trace > ChaseX Delay.
These commands behave as follows:
•
TraceX / TraceX Delay— Steps back to the last driver of an X value. TraceX
Delay works similarly but it steps back in time to the last driver of an X value.
TraceX should be used for RTL designs; TraceX Delay should be used for gatelevel netlists with back annotated delays.
•
ChaseX / ChaseX Delay — "Jumps" through a design from output to input, following X values. ChaseX Delay acts the same as ChaseX but also moves backwards in time to the point where the output value transitions to X. ChaseX should be used for RTL designs; ChaseX Delay should be used for gate-level netlists with back annotated delays.
Finding Objects by Name in the Dataflow
Window
Select Edit > Find from the menu bar, or click the Find icon in the toolbar, to search for signal, net, or register names or an instance of a component. This opens the Find in
Dataflow dialog (
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Printing and Saving the Display
Figure 9-5. Find in Dataflow Dialog
With the Find in Dataflow dialog you can limit the search by type to instances or signals. You select Exact to find an item that exactly matches the entry you’ve typed in the Find field. The
Match case selection will enforce case-sensitive matching of your entry. And the Zoom to selection will zoom in to the item in Find field.
The Find All button allows you to find and highlight all occurrences of the item in the Find field. If Zoom to is checked, the view will change such that all selected items are viewable. If
Zoom to is not selected, then no change is made to zoom or scroll state.
Printing and Saving the Display
Saving a .eps File and Printing the Dataflow Display from
UNIX
Select File > Print Postscript to setup and print the Dataflow display in UNIX, or save the waveform as a .eps file on any platform.
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Printing and Saving the Display
Figure 9-6. The Print Postscript Dialog
Printing from the Dataflow Display on Windows Platforms
Select File > Print to print the Dataflow display or to save the display to a file.
Figure 9-7. The Print Dialog
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Configuring Page Setup
Configuring Page Setup
Clicking the Setup button in the Print Postscript or Print dialog box allows you to configure page view, highlight, color mode, orientation, and paper options (this is the same dialog that opens via File > Page setup).
Figure 9-8. The Dataflow Page Setup Dialog
Symbol Mapping
The Dataflow window has built-in mappings for all Verilog primitive gates (i.e., AND, OR, etc.). For components other than Verilog primitives, you can define a mapping between processes and built-in symbols. This is done through a file containing name pairs, one per line, where the first name is the concatenation of the design unit and process names,
(DUname.Processname), and the second name is the name of a built-in symbol. For example: xorg(only).p1 XOR org(only).p1 OR andg(only).p1 AND
Entities and modules are mapped the same way:
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Symbol Mapping
AND1 AND
AND2 AND # A 2-input and gate
AND3 AND
AND4 AND
AND5 AND
AND6 AND xnor(test) XNOR
Note that for primitive gate symbols, pin mapping is automatic.
The Dataflow window looks in the current working directory and inside each library referenced by the design for the file dataflow.bsm (.bsm stands for "Built-in Symbol Map"). It will read all files found.
User-defined symbols
You can also define your own symbols using an ASCII symbol library file format for defining symbol shapes. This capability is delivered via Concept Engineering’s Nlview
TM
widget
Symlib format.
The Dataflow window will search the current working directory, and inside each library referenced by the design, for the file dataflow.sym. Any and all files found will be given to the
Nlview widget to use for symbol lookups. Again, as with the built-in symbols, the DU name and optional process name is used for the symbol lookup. Here's an example of a symbol for a full adder: symbol adder(structural) * DEF \ port a in -loc -12 -15 0 -15 \ pinattrdsp @name -cl 2 -15 8 \ port b in -loc -12 15 0 15 \ pinattrdsp @name -cl 2 15 8 \ port cin in -loc 20 -40 20 -28 \ pinattrdsp @name -uc 19 -26 8 \ port cout out -loc 20 40 20 28 \ pinattrdsp @name -lc 19 26 8 \ port sum out -loc 63 0 51 0 \ pinattrdsp @name -cr 49 0 8 \ path 10 0 0 7 \ path 0 7 0 35 \ path 0 35 51 17 \ path 51 17 51 -17 \ path 51 -17 0 -35 \ path 0 -35 0 -7 \ path 0 -7 10 0
Port mapping is done by name for these symbols, so the port names in the symbol definition must match the port names of the Entity|Module|Process (in the case of the process, it’s the signal names that the process reads/writes).
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Configuring Window Options
Note
When you create or modify a symlib file, you must generate a file index. This index is how the Nlview widget finds and extracts symbols from the file. To generate the index, select Tools > Create symlib index (Dataflow window) and specify the symlib file. The file will be rewritten with a correct, up-to-date index.
Configuring Window Options
You can configure several options that determine how the Dataflow window behaves. The settings affect only the current session.
Select Tools > Options to open the Dataflow Options dialog box.
Figure 9-9. Configuring Dataflow Options
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Chapter 10
Signal Spy
The Verilog language allows access to any signal from any other hierarchical block without having to route it via the interface. This means you can use hierarchical notation to either assign or determine the value of a signal in the design hierarchy from a testbench. This capability fails when a Verilog testbench attempts to reference a signal in a VHDL block or reference a signal in a Verilog block through a VHDL level of hierarchy.
This limitation exists because VHDL does not allow hierarchical notation. In order to reference internal hierarchical signals, you have to resort to defining signals in a global package and then utilize those signals in the hierarchical blocks in question. But, this requires that you keep making changes depending on the signals that you want to reference.
The Signal Spy procedures and system tasks overcome the aforementioned limitations. They allow you to monitor (spy), drive, force, or release hierarchical objects in a VHDL or mixed design.
The VHDL procedures are provided via the
Util Package within the modelsim_lib library. To
access the procedures you would add lines like the following to your VHDL code: library modelsim_lib; use modelsim_lib.util.all;
The Verilog tasks are available as built-in
System Tasks and Functions . The table below shows
the VHDL procedures and their corresponding Verilog system tasks.
Table 10-1. Signal Spy: Mapping VHDL Procedures to Verilog System Tasks
VHDL procedures Verilog system tasks
Designed for Testbenches
Signal Spy limits the portability of your code. HDL code with Signal Spy procedures or tasks works only in ModelSim, not other simulators. We therefore recommend using Signal Spy only
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Signal Spy in testbenches, where portability is less of a concern, and the need for such a tool is more applicable.
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disable_signal_spy
disable_signal_spy
The disable_signal_spy() procedure disables the associated init_signal_spy. The association between the disable_signal_spy call and the init_signal_spy call is based on specifying the same src_object and dest_object arguments to both functions. The disable_signal_spy call can only affect init_signal_spy calls that had their control_state argument set to "0" or "1".
Syntax
disable_signal_spy(<src_object>, <dest_object>, <verbose>)
Returns
Nothing
Arguments
• src_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog register/net. This path should match the path that was specified in the init_signal_spy call that you wish to disable.
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog register/net. This path should match the path that was specified in the init_signal_spy call that you wish to disable.
• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the transcript stating that a disable occurred and the simulation time that it occurred.
Default is 0, no message
Related procedures
,
Example
See init_signal_spy Example
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enable_signal_spy
enable_signal_spy
The enable_signal_spy() procedure enables the associated init_signal_spy. The association between the enable_signal_spy call and the init_signal_spy call is based on specifying the same src_object and dest_object arguments to both functions. The enable_signal_spy call can only affect init_signal_spy calls that had their control_state argument set to "0" or "1".
Syntax
enable_signal_spy(<src_object>, <dest_object>, <verbose>)
Returns
Nothing
Arguments
• src_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog register/net. This path should match the path that was specified in the init_signal_spy call that you wish to enable.
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog register/net. This path should match the path that was specified in the init_signal_spy call that you wish to enable.
• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the transcript stating that an enable occurred and the simulation time that it occurred.
Default is 0, no message
Related procedures
,
Example
See init_signal_spy Example
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init_signal_driver
init_signal_driver
The init_signal_driver() procedure drives the value of a VHDL signal or Verilog net (called the src_object) onto an existing VHDL signal or Verilog net (called the dest_object). This allows you to drive signals or nets at any level of the design hierarchy from within a VHDL architecture (e.g., a testbench).
The init_signal_driver procedure drives the value onto the destination signal just as if the signals were directly connected in the HDL code. Any existing or subsequent drive or force of the destination signal, by some other means, will be considered with the init_signal_driver value in the resolution of the signal.
Call only once
The init_signal_driver procedure creates a persistent relationship between the source and destination signals. Hence, you need to call init_signal_driver only once for a particular pair of signals. Once init_signal_driver is called, any change on the source signal will be driven on the destination signal until the end of the simulation.
Thus, we recommend that you place all init_signal_driver calls in a VHDL process. You need to code the VHDL process correctly so that it is executed only once. The VHDL process should not be sensitive to any signals and should contain only init_signal_driver calls and a simple wait statement. The process will execute once and then wait forever. See the example below.
Syntax
init_signal_driver(<src_object>, <dest_object>, <delay>, <delay_type>, <verbose>)
Returns
Nothing
Arguments
• src_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog net. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or ".". The path must be contained within double quotes.
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to an existing VHDL signal or Verilog net. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or ".".
The path must be contained within double quotes.
• delay
Optional time value. Specifies a delay relative to the time at which the src_object changes.
The delay can be an inertial or transport delay. If no delay is specified, then a delay of zero is assumed.
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init_signal_driver
• delay_type
Optional del_mode. Specifies the type of delay that will be applied. The value must be either mti_inertial or mti_transport. The default is mti_inertial.
• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the Transcript stating that the src_object is driving the dest_object. Default is 0, no message.
Related procedures
,
Limitations
•
When driving a Verilog net, the only delay_type allowed is inertial. If you set the delay type to mti_transport, the setting will be ignored and the delay type will be mti_inertial.
•
Any delays that are set to a value less than the simulator resolution will be rounded to the nearest resolution unit; no special warning will be issued.
init_signal_driver Example
This example creates a local clock (clk0) and connects it to two clocks within the design hierarchy. The .../blk1/clk will match local clk0 and a message will be displayed. The open entries allow the default delay and delay_type while setting the verbose parameter to a 1. The
.../blk2/clk will match the local clk0 but be delayed by 100 ps.
library IEEE, modelsim_lib; use IEEE.std_logic_1164.all; use modelsim_lib.util.all; entity testbench is end; architecture only of testbench is signal clk0 : std_logic; begin gen_clk0 : process begin clk0 <= '1' after 0 ps, '0' after 20 ps; wait for 40 ps; end process gen_clk0; drive_sig_process : process begin init_signal_driver("clk0", "/testbench/uut/blk1/clk", open, open, 1); init_signal_driver("clk0", "/testbench/uut/blk2/clk", 100 ps, mti_transport); wait; end process drive_sig_process;
...
end;
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init_signal_spy
init_signal_spy
The init_signal_spy() procedure mirrors the value of a VHDL signal or Verilog register/net
(called the src_object) onto an existing VHDL signal or Verilog register (called the dest_object). This allows you to reference signals, registers, or nets at any level of hierarchy from within a VHDL architecture (e.g., a testbench).
The init_signal_spy procedure only sets the value onto the destination signal and does not drive or force the value. Any existing or subsequent drive or force of the destination signal, by some other means, will override the value that was set by init_signal_spy.
Call only once
The init_signal_spy procedure creates a persistent relationship between the source and destination signals. Hence, you need to call init_signal_spy once for a particular pair of signals.
Once init_signal_spy is called, any change on the source signal will mirror on the destination signal until the end of the simulation unless the control_state is set.
The control_state determines whether the mirroring of values can be enabled/disabled and what the initial state is. Subsequent control of whether the mirroring of values is enabled/disabled is handled by the enable_signal_spy and disable_signal_spy calls.
We recommend that you place all init_signal_spy calls in a VHDL process. You need to code the VHDL process correctly so that it is executed only once. The VHDL process should not be sensitive to any signals and should contain only init_signal_spy calls and a simple wait statement. The process will execute once and then wait forever, which is the desired behavior.
See the example below.
Syntax
init_signal_spy(<src_object>, <dest_object>, <verbose>, <control_state>)
Returns
Nothing
Arguments
• src_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog register/net. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or ".".
The path must be contained within double quotes.
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to an existing VHDL signal or Verilog register. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or
".". The path must be contained within double quotes.
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• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the Transcript stating that the src_object’s value is mirrored onto the dest_object. Default is 0, no message.
• control_state
Optional integer. Possible values are -1, 0, or 1. Specifies whether or not you want the ability to enable/disable mirroring of values and, if so, specifies the initial state. The default is -1, no ability to enable/disable and mirroring is enabled. "0" turns on the ability to enable/disable and initially disables mirroring. "1" turns on the ability to enable/disable and initially enables mirroring.
Related procedures
,
,
Limitations
•
When mirroring the value of a Verilog register/net onto a VHDL signal, the VHDL signal must be of type bit, bit_vector, std_logic, or std_logic_vector.
•
Verilog memories (arrays of registers) are not supported.
init_signal_spy Example
In this example, the value of /top/uut/inst1/sig1 is mirrored onto /top/top_sig1. A message is issued to the transcript. The ability to control the mirroring of values is turned on and the init_signal_spy is initially enabled.
The mirroring of values will be disabled when enable_sig transitions to a ’0’ and enable when enable_sig transitions to a ’1’.
library ieee; library modelsim_lib; use ieee.std_logic_1164.all; use modelsim_lib.util.all; entity top is end; architecture only of top is signal top_sig1 : std_logic; begin
...
spy_process : process begin init_signal_spy("/top/uut/inst1/sig1","/top/top_sig1",1,1); wait; end process spy_process;
...
spy_enable_disable : process(enable_sig) begin if (enable_sig = '1') then enable_signal_spy("/top/uut/inst1/sig1","/top/top_sig1",0); elseif (enable_sig = '0')
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init_signal_spy
end process spy_enable_disable;
...
end; disable_signal_spy("/top/uut/inst1/sig1","/top/top_sig1",0); end if;
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signal_force
signal_force
The signal_force() procedure forces the value specified onto an existing VHDL signal or
Verilog register or net (called the dest_object). This allows you to force signals, registers, or nets at any level of the design hierarchy from within a VHDL architecture (e.g., a testbench).
A signal_force works the same as the force command with the exception that you cannot issue a repeating force. The force will remain on the signal until a signal_release, a force or release command, or a subsequent signal_force is issued. Signal_force can be called concurrently or sequentially in a process.
This command acquires displays any signals using your radix setting (either the default, or as you specify) unless you specify the radix in the value you set.
Syntax
signal_force(<dest_object>, <value>, <rel_time>, <force_type>, <cancel_period>, <verbose>)
Returns
Nothing
Arguments
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to an existing VHDL signal or Verilog register/net. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or
".". The path must be contained within double quotes.
• value
Required string. Specifies the value to which the dest_object is to be forced. The specified value must be appropriate for the type.
• rel_time
Optional time. Specifies a time relative to the current simulation time for the force to occur.
The default is 0.
• force_type
Optional forcetype. Specifies the type of force that will be applied. The value must be one of the following; default, deposit, drive, or freeze. The default is "default" (which is "freeze" for unresolved objects or "drive" for resolved objects). See the force command for further details on force type.
• cancel_period
Optional time. Cancels the signal_force command after the specified period of time units.
Cancellation occurs at the last simulation delta cycle of a time unit. A value of zero cancels the force at the end of the current time period. Default is -1 ms. A negative value means that the force will not be cancelled.
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• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the Transcript stating that the value is being forced on the dest_object at the specified time. Default is 0, no message.
Related procedures
,
Limitations
You cannot force bits or slices of a register; you can force only the entire register.
signal_force Example
This example forces reset to a "1" from time 0 ns to 40 ns. At 40 ns, reset is forced to a "0", 2 ms after the second signal_force call was executed.
If you want to skip parameters so that you can specify subsequent parameters, you need to use the keyword "open" as a placeholder for the skipped parameter(s). The first signal_force procedure illustrates this, where an "open" for the cancel_period parameter means that the default value of -1 ms is used.
library IEEE, modelsim_lib; use IEEE.std_logic_1164.all; use modelsim_lib.util.all; entity testbench is end; architecture only of testbench is begin force_process : process begin signal_force("/testbench/uut/blk1/reset", "1", 0 ns, freeze, open, 1); signal_force("/testbench/uut/blk1/reset", "0", 40 ns, freeze, 2 ms,
1); wait; end process force_process;
...
end;
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signal_release
signal_release
The signal_release() procedure releases any force that was applied to an existing VHDL signal or Verilog register/net (called the dest_object). This allows you to release signals, registers or nets at any level of the design hierarchy from within a VHDL architecture (e.g., a testbench).
A signal_release works the same as the noforce command. Signal_release can be called concurrently or sequentially in a process.
Syntax
signal_release(<dest_object>, <verbose>)
Returns
Nothing
Arguments
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to an existing VHDL signal or Verilog register/net. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or
".". The path must be contained within double quotes.
• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the Transcript stating that the signal is being released and the time of the release. Default is 0, no message.
Related procedures
,
Limitations
•
You cannot release a bit or slice of a register; you can release only the entire register.
signal_release Example
This example releases any forces on the signals data and clk when the signal release_flag is a
"1". Both calls will send a message to the transcript stating which signal was released and when.
library IEEE, modelsim_lib; use IEEE.std_logic_1164.all; use modelsim_lib.util.all; entity testbench is end; architecture only of testbench is signal release_flag : std_logic;
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begin stim_design : process begin
...
wait until release_flag = '1'; signal_release("/testbench/dut/blk1/data", 1); signal_release("/testbench/dut/blk1/clk", 1);
...
end process stim_design;
...
end;
Signal Spy
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$disable_signal_spy
$disable_signal_spy
The $disable_signal_spy() system task disables the associated $init_signal_spy task. The association between the $disable_signal_spy task and the $init_signal_spy task is based on specifying the same src_object and dest_object arguments to both tasks. The
$disable_signal_spy task can only affect $init_signal_spy tasks that had their control_state argument set to "0" or "1".
Syntax
$disable_signal_spy(<src_object>, <dest_object>, <verbose>)
Returns
Nothing
Arguments
• src_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog register/net. This path should match the path that was specified in the init_signal_spy call that you wish to disable.
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog register/net. This path should match the path that was specified in the init_signal_spy call that you wish to disable.
• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the transcript stating that a disable occurred and the simulation time that it occurred.
Default is 0, no message
Related tasks
,
Example
See $init_signal_spy Example
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$enable_signal_spy
$enable_signal_spy
The $enable_signal_spy() system task enables the associated $init_signal_spy task. The association between the $enable_signal_spy task and the $init_signal_spy task is based on specifying the same src_object and dest_object arguments to both tasks. The
$enable_signal_spy task can only affect $init_signal_spys tasks that had their control_state argument set to "0" or "1".
Syntax
$enable_signal_spy(<src_object>, <dest_object>, <verbose>)
Returns
Nothing
Arguments
• src_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog register/net. This path should match the path that was specified in the init_signal_spy call that you wish to enable.
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog register/net. This path should match the path that was specified in the init_signal_spy call that you wish to enable.
• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the transcript stating that an enable occurred and the simulation time that it occurred.
Default is 0, no message
Related tasks
,
Example
See $init_signal_spy Example
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$init_signal_driver
$init_signal_driver
The $init_signal_driver() system task drives the value of a VHDL signal or Verilog net (called the src_object) onto an existing VHDL signal or Verilog register/net (called the dest_object).
This allows you to drive signals or nets at any level of the design hierarchy from within a
Verilog module (e.g., a testbench).
The $init_signal_driver system task drives the value onto the destination signal just as if the signals were directly connected in the HDL code. Any existing or subsequent drive or force of the destination signal, by some other means, will be considered with the $init_signal_driver value in the resolution of the signal.
Call only once
The $init_signal_driver system task creates a persistent relationship between the source and destination signals. Hence, you need to call $init_signal_driver only once for a particular pair of signals. Once $init_signal_driver is called, any change on the source signal will be driven on the destination signal until the end of the simulation.
Thus, we recommend that you place all $init_signal_driver calls in a Verilog initial block. See the example below.
Syntax
$init_signal_driver(<src_object>, <dest_object>, <delay>, <delay_type>, <verbose>)
Returns
Nothing
Arguments
• src_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog net. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or ".". The path must be contained within double quotes.
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to an existing VHDL signal or Verilog net. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or ".".
The path must be contained within double quotes.
• delay
Optional integer, real, or time. Specifies a delay relative to the time at which the src_object changes. The delay can be an inertial or transport delay. If no delay is specified, then a delay of zero is assumed.
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$init_signal_driver
• delay_type
Optional integer. Specifies the type of delay that will be applied. The value must be either 0
(inertial) or 1 (transport). The default is 0.
• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the Transcript stating that the src_object is driving the dest_object. Default is 0, no message.
Related tasks
,
Limitations
•
When driving a Verilog net, the only delay_type allowed is inertial. If you set the delay type to 1 (transport), the setting will be ignored, and the delay type will be inertial.
•
Any delays that are set to a value less than the simulator resolution will be rounded to the nearest resolution unit; no special warning will be issued.
•
Verilog memories (arrays of registers) are not supported.
$init_signal_driver Example
This example creates a local clock (clk0) and connects it to two clocks within the design hierarchy. The .../blk1/clk will match local clk0 and a message will be displayed. The .../blk2/clk will match the local clk0 but be delayed by 100 ps. For the second call to work, the .../blk2/clk must be a VHDL based signal, because if it were a Verilog net a 100 ps inertial delay would consume the 40 ps clock period. Verilog nets are limited to only inertial delays and thus the setting of 1 (transport delay) would be ignored.
`timescale 1 ps / 1 ps module testbench; reg clk0; initial begin clk0 = 1; forever begin
#20 clk0 = ~clk0; end end initial begin
$init_signal_driver("clk0", "/testbench/uut/blk1/clk", , , 1); end
$init_signal_driver("clk0", "/testbench/uut/blk2/clk", 100, 1);
...
endmodule
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$init_signal_spy
$init_signal_spy
The $init_signal_spy() system task mirrors the value of a VHDL signal or Verilog register/net
(called the src_object) onto an existing VHDL signal or Verilog register (called the dest_object). This allows you to reference signals, registers, or nets at any level of hierarchy from within a Verilog module (e.g., a testbench).
The $init_signal_spy system task only sets the value onto the destination signal and does not drive or force the value. Any existing or subsequent drive or force of the destination signal, by some other means, will override the value set by $init_signal_spy.
Call only once
The $init_signal_spy system task creates a persistent relationship between the source and the destination signal. Hence, you need to call $init_signal_spy only once for a particular pair of signals. Once $init_signal_spy is called, any change on the source signal will mirror on the destination signal until the end of the simulation unless the control_state is set.
The control_state determines whether the mirroring of values can be enabled/disabled and what the initial state is. Subsequent control of whether the mirroring of values is enabled/disabled is handled by the $enable_signal_spy and $disable_signal_spy tasks.
We recommend that you place all $init_signal_spy tasks in a Verilog initial block. See the example below.
Syntax
$init_signal_spy(<src_object>, <dest_object>, <verbose>, <control_state>)
Returns
Nothing
Arguments
• src_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a VHDL signal or Verilog register/net. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or ".".
The path must be contained within double quotes.
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to a Verilog register or VHDL signal. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or ".". The path must be contained within double quotes.
• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the Transcript stating that the src_object’s value is mirrored onto the dest_object. Default is 0, no message.
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• control_state
Optional integer. Possible values are -1, 0, or 1. Specifies whether or not you want the ability to enable/disable mirroring of values and, if so, specifies the initial state. The default is -1, no ability to enable/disable and mirroring is enabled. "0" turns on the ability to enable/disable and initially disables mirroring. "1" turns on the ability to enable/disable and initially enables mirroring.
Related tasks
,
Limitations
•
When mirroring the value of a VHDL signal onto a Verilog register, the VHDL signal must be of type bit, bit_vector, std_logic, or std_logic_vector.
•
Verilog memories (arrays of registers) are not supported.
$init_signal_spy Example
In this example, the value of .top.uut.inst1.sig1 is mirrored onto .top.top_sig1. A message is issued to the transcript. The ability to control the mirroring of values is turned on and the init_signal_spy is initially enabled.
The mirroring of values will be disabled when enable_reg transitions to a ’0’ and enabled when enable_reg transitions to a ’1’.
module top;
...
reg top_sig1; reg enable_reg;
...
initial begin
$init_signal_spy(".top.uut.inst1.sig1",".top.top_sig1",1,1); end always @ (posedge enable_reg) begin
$enable_signal_spy(".top.uut.inst1.sig1",".top.top_sig1",0); end always @ (negedge enable_reg) begin
$disable_signal_spy(".top.uut.inst1.sig1",".top.top_sig1",0); end
...
endmodule
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$signal_force
$signal_force
The $signal_force() system task forces the value specified onto an existing VHDL signal or
Verilog register/net (called the dest_object). This allows you to force signals, registers, or nets at any level of the design hierarchy from within a Verilog module (e.g., a testbench).
A $signal_force works the same as the force command with the exception that you cannot issue a repeating force. The force will remain on the signal until a $signal_release, a force or release command, or a subsequent $signal_force is issued. $signal_force can be called concurrently or sequentially in a process.
Syntax
$signal_force(<dest_object>, <value>, <rel_time>, <force_type>, <cancel_period>,
<verbose>)
Returns
Nothing
Arguments
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to an existing VHDL signal or Verilog register/net. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or
".". The path must be contained within double quotes.
• value
Required string. Specifies the value to which the dest_object is to be forced. The specified value must be appropriate for the type.
• rel_time
Optional integer, real, or time. Specifies a time relative to the current simulation time for the force to occur. The default is 0.
• force_type
Optional integer. Specifies the type of force that will be applied. The value must be one of the following; 0 (default), 1 (deposit), 2 (drive), or 3 (freeze). The default is "default"
(which is "freeze" for unresolved objects or "drive" for resolved objects). See the force command for further details on force type.
• cancel_period
Optional integer, real, time. Cancels the $signal_force command after the specified period of time units. Cancellation occurs at the last simulation delta cycle of a time unit. A value of zero cancels the force at the end of the current time period. Default is -1. A negative value means that the force will not be cancelled.
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$signal_force
• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the Transcript stating that the value is being forced on the dest_object at the specified time. Default is 0, no message.
Related tasks
,
Limitations
•
You cannot force bits or slices of a register; you can force only the entire register.
•
Verilog memories (arrays of registers) are not supported.
$signal_force Example
This example forces reset to a "1" from time 0 ns to 40 ns. At 40 ns, reset is forced to a "0",
200000 ns after the second $signal_force call was executed.
`timescale 1 ns / 1 ns module testbench; initial begin
$signal_force("/testbench/uut/blk1/reset", "1", 0, 3, , 1);
$signal_force("/testbench/uut/blk1/reset", "0", 40, 3, 200000, 1); end
...
endmodule
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$signal_release
$signal_release
The $signal_release() system task releases any force that was applied to an existing VHDL signal or Verilog register/net (called the dest_object). This allows you to release signals, registers, or nets at any level of the design hierarchy from within a Verilog module (e.g., a testbench).
A $signal_release works the same as the noforce command. $signal_release can be called concurrently or sequentially in a process.
Syntax
$signal_release(<dest_object>, <verbose>)
Returns
Nothing
Arguments
• dest_object
Required string. A full hierarchical path (or relative downward path with reference to the calling block) to an existing VHDL signal or Verilog register/net. Use the path separator to which your simulation is set (i.e., "/" or "."). A full hierarchical path must begin with a "/" or
".". The path must be contained within double quotes.
• verbose
Optional integer. Possible values are 0 or 1. Specifies whether you want a message reported in the Transcript stating that the signal is being released and the time of the release. Default is 0, no message.
Related tasks
,
Limitations
•
You cannot release a bit or slice of a register; you can release only the entire register.
$signal_release Example
This example releases any forces on the signals data and clk when the register release_flag transitions to a "1". Both calls will send a message to the transcript stating which signal was released and when.
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module testbench; reg release_flag; always @(posedge release_flag) begin
$signal_release("/testbench/dut/blk1/data", 1);
$signal_release("/testbench/dut/blk1/clk", 1); end
...
endmodule
Signal Spy
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Chapter 11
Standard Delay Format (SDF) Timing
Annotation
This chapter discusses ModelSim’s implementation of SDF (Standard Delay Format) timing annotation. Included are sections on VITAL SDF and Verilog SDF, plus troubleshooting.
Verilog and VHDL VITAL timing data can be annotated from SDF files by using the simulator’s built-in SDF annotator.
Note
SDF timing annotations can be applied only to your FPGA vendor’s libraries; all other libraries will simulate without annotation.
Specifying SDF Files for Simulation
ModelSim supports SDF versions 1.0 through 4.0 (except the NETDELAY statement). The simulator’s built-in SDF annotator automatically adjusts to the version of the file. Use the following vsim command-line options to specify the SDF files, the desired timing values, and their associated design instances:
-sdfmin [<instance>=]<filename>
-sdftyp [<instance>=]<filename>
-sdfmax [<instance>=]<filename>
Any number of SDF files can be applied to any instance in the design by specifying one of the above options for each file. Use -sdfmin to select minimum, -sdftyp to select typical, and
-sdfmax to select maximum timing values from the SDF file.
Instance Specification
The instance paths in the SDF file are relative to the instance to which the SDF is applied.
Usually, this instance is an ASIC or FPGA model instantiated under a testbench. For example, to annotate maximum timing values from the SDF file myasic.sdf to an instance u1 under a toplevel named testbench, invoke the simulator as follows:
vsim -sdfmax /testbench/u1=myasic.sdf testbench
If the instance name is omitted then the SDF file is applied to the top-level. This is usually
incorrect because in most cases the model is instantiated under a testbench or within a larger system level simulation. In fact, the design can have several models, each having its own SDF file. In this case, specify an SDF file for each instance. For example,
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Specifying SDF Files for Simulation vsim -sdfmax /system/u1=asic1.sdf -sdfmax /system/u2=asic2.sdf system
SDF Specification with the GUI
As an alternative to the command-line options, you can specify SDF files in the Start
Simulation dialog box under the SDF tab.
Figure 11-1. SDF Tab in Start Simulation Dialog
You can access this dialog by invoking the simulator without any arguments or by selecting
Simulate > Start Simulation. See the GUI chapter for a description of this dialog.
For Verilog designs, you can also specify SDF files by using the $sdf_annotate system task.
See
$sdf_annotate for more details.
Errors and Warnings
Errors issued by the SDF annotator while loading the design prevent the simulation from continuing, whereas warnings do not. Use the -sdfnoerror option with vsim to change SDF errors to warnings so that the simulation can continue. Warning messages can be suppressed by using vsim with either the -sdfnowarn or +nosdfwarn options.
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VHDL VITAL SDF
Another option is to use the SDF tab from the Start Simulation dialog box (shown above).
Select Disable SDF warnings (-sdfnowarn +nosdfwarn) to disable warnings, or select Reduce
SDF errors to warnings (-sdfnoerror) to change errors to warnings.
See
Troubleshooting for more information on errors and warnings and how to avoid them.
VHDL VITAL SDF
VHDL SDF annotation works on VITAL cells only. The IEEE 1076.4 VITAL ASIC Modeling
Specification describes how cells must be written to support SDF annotation. Once again, the designer does not need to know the details of this specification because the library provider has already written the VITAL cells and tools that create compatible SDF files. However, the following summary may help you understand simulator error messages. For additional VITAL specification information, see
VITAL Specification and Source Code .
SDF to VHDL Generic Matching
An SDF file contains delay and timing constraint data for cell instances in the design. The annotator must locate the cell instances and the placeholders (VHDL generics) for the timing data. Each type of SDF timing construct is mapped to the name of a generic as specified by the
VITAL modeling specification. The annotator locates the generic and updates it with the timing value from the SDF file. It is an error if the annotator fails to find the cell instance or the named generic. The following are examples of SDF constructs and their associated generic names:
Table 11-1. Matching SDF to VHDL Generics
SDF construct Matching VHDL generic name
(IOPATH a y (3))
(IOPATH (posedge clk) q (1) (2)) tpd_a_y tpd_clk_q_posedge
(INTERCONNECT u1/y u2/a (5))
(SETUP d (posedge clk) (5)) tipd_a tsetup_d_clk_noedge_posedge
(HOLD (negedge d) (posedge clk) (5)) thold_d_clk_negedge_posedge
(SETUPHOLD d clk (5) (5)) tsetup_d_clk & thold_d_clk
(WIDTH (COND (reset==1’b0) clk) (5)) tpw_clk_reset_eq_0
The SDF statement CONDELSE, when targeted for Vital cells, is annotated to a tpd generic of the form tpd_<inputPort>_<outputPort>.
Resolving Errors
If the simulator finds the cell instance but not the generic then an error message is issued. For example,
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Verilog SDF
** Error (vsim-SDF-3240) myasic.sdf(18):
Instance ’/testbench/dut/u1’ does not have a generic named ’tpd_a_y’
In this case, make sure that the design is using the appropriate VITAL library cells. If it is, then there is probably a mismatch between the SDF and the VITAL cells. You need to find the cell instance and compare its generic names to those expected by the annotator. Look in the VHDL source files provided by the cell library vendor.
If none of the generic names look like VITAL timing generic names, then perhaps the VITAL library cells are not being used. If the generic names do look like VITAL timing generic names but don’t match the names expected by the annotator, then there are several possibilities:
•
The vendor’s tools are not conforming to the VITAL specification.
•
The SDF file was accidentally applied to the wrong instance. In this case, the simulator also issues other error messages indicating that cell instances in the SDF could not be located in the design.
•
The vendor’s library and SDF were developed for the older VITAL 2.2b specification.
This version uses different name mapping rules. In this case, invoke vsim with the
-vital2.2b option:
vsim -vital2.2b -sdfmax /testbench/u1=myasic.sdf testbench
For more information on resolving errors see
Verilog SDF
Verilog designs can be annotated using either the simulator command-line options or the
$sdf_annotate system task (also commonly used in other Verilog simulators). The commandline options annotate the design immediately after it is loaded, but before any simulation events take place. The $sdf_annotate task annotates the design at the time it is called in the Verilog source code. This provides more flexibility than the command-line options.
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$sdf_annotate
$sdf_annotate
Syntax
$sdf_annotate
(["<sdffile>"], [<instance>], ["<config_file>"], ["<log_file>"], ["<mtm_spec>"],
["<scale_factor>"], ["<scale_type>"]);
Arguments
•
"<sdffile>"
String that specifies the SDF file. Required.
•
<instance>
Hierarchical name of the instance to be annotated. Optional. Defaults to the instance where the $sdf_annotate call is made.
•
"<config_file>"
String that specifies the configuration file. Optional. Currently not supported, this argument is ignored.
•
"<log_file>"
String that specifies the logfile. Optional. Currently not supported, this argument is ignored.
•
"<mtm_spec>"
String that specifies the delay selection. Optional. The allowed strings are "minimum",
"typical", "maximum", and "tool_control". Case is ignored and the default is "tool_control".
The "tool_control" argument means to use the delay specified on the command line by
+mindelays, +typdelays, or +maxdelays (defaults to +typdelays).
•
"<scale_factor>"
String that specifies delay scaling factors. Optional. The format is
"<min_mult>:<typ_mult>:<max_mult>". Each multiplier is a real number that is used to scale the corresponding delay in the SDF file.
•
"<scale_type>"
String that overrides the <mtm_spec> delay selection. Optional. The <mtm_spec> delay selection is always used to select the delay scaling factor, but if a <scale_type> is specified, then it will determine the min/typ/max selection from the SDF file. The allowed strings are
"from_min", "from_minimum", "from_typ", "from_typical", "from_max",
"from_maximum", and "from_mtm". Case is ignored, and the default is "from_mtm", which means to use the <mtm_spec> value.
Examples
Optional arguments can be omitted by using commas or by leaving them out if they are at the end of the argument list. For example, to specify only the SDF file and the instance to which it applies:
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$sdf_annotate
$sdf_annotate("myasic.sdf", testbench.u1);
To also specify maximum delay values:
$sdf_annotate("myasic.sdf", testbench.u1, , , "maximum");
SDF to Verilog Construct Matching
The annotator matches SDF constructs to corresponding Verilog constructs in the cells.
Usually, the cells contain path delays and timing checks within specify blocks. For each SDF construct, the annotator locates the cell instance and updates each specify path delay or timing check that matches. An SDF construct can have multiple matches, in which case each matching specify statement is updated with the SDF timing value. SDF constructs are matched to Verilog constructs as follows.
•
IOPATH is matched to specify path delays or primitives:
SDF
Table 11-2. Matching SDF IOPATH to Verilog
Verilog
(IOPATH (posedge clk) q (3) (4)) (posedge clk => q) = 0;
(IOPATH a y (3) (4)) buf u1 (y, a);
The IOPATH construct usually annotates path delays. If ModelSim can’t locate a corresponding specify path delay, it returns an error unless you use the
+sdf_iopath_to_prim_ok argument to vsim . If you specify that argument and the module contains no path delays, then all primitives that drive the specified output port are annotated.
•
INTERCONNECT and PORT are matched to input ports:
Table 11-3. Matching SDF INTERCONNECT and PORT to Verilog
SDF Verilog
(INTERCONNECT u1.y u2.a (5)) input a;
(PORT u2.a (5)) inout a;
Both of these constructs identify a module input or inout port and create an internal net that is a delayed version of the port. This is called a Module Input Port Delay (MIPD).
All primitives, specify path delays, and specify timing checks connected to the original port are reconnected to the new MIPD net.
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$sdf_annotate
•
PATHPULSE and GLOBALPATHPULSE are matched to specify path delays:
Table 11-4. Matching SDF PATHPULSE and GLOBALPATHPULSE to Verilog
SDF Verilog
(PATHPULSE a y (5) (10)) (a => y) = 0;
(GLOBALPATHPULSE a y (30) (60)) (a => y) = 0;
If the input and output ports are omitted in the SDF, then all path delays are matched in the cell.
•
DEVICE is matched to primitives or specify path delays:
Table 11-5. Matching SDF DEVICE to Verilog
SDF Verilog
(DEVICE y (5))
(DEVICE y (5)) and u1(y, a, b);
(a => y) = 0; (b => y) = 0;
If the SDF cell instance is a primitive instance, then that primitive’s delay is annotated.
If it is a module instance, then all specify path delays are annotated that drive the output port specified in the DEVICE construct (all path delays are annotated if the output port is omitted). If the module contains no path delays, then all primitives that drive the specified output port are annotated (or all primitives that drive any output port if the output port is omitted).
SETUP is matched to $setup and $setuphold:
Table 11-6. Matching SDF SETUP to Verilog
SDF
(SETUP d (posedge clk) (5))
Verilog
$setup(d, posedge clk, 0);
(SETUP d (posedge clk) (5)) $setuphold(posedge clk, d, 0, 0);
•
HOLD is matched to $hold and $setuphold:
Table 11-7. Matching SDF HOLD to Verilog
SDF
(HOLD d (posedge clk) (5))
Verilog
$hold(posedge clk, d, 0);
(HOLD d (posedge clk) (5)) $setuphold(posedge clk, d, 0, 0);
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$sdf_annotate
•
SETUPHOLD is matched to $setup, $hold, and $setuphold:
Table 11-8. Matching SDF SETUPHOLD to Verilog
SDF
(SETUPHOLD d (posedge clk) (5) (5))
Verilog
$setup(d, posedge clk, 0);
(SETUPHOLD d (posedge clk) (5) (5))
(SETUPHOLD d (posedge clk) (5) (5))
$hold(posedge clk, d, 0);
$setuphold(posedge clk, d, 0, 0);
•
RECOVERY is matched to $recovery:
Table 11-9. Matching SDF RECOVERY to Verilog
SDF
(RECOVERY (negedge reset) (posedge clk)
(5))
Verilog
$recovery(negedge reset, posedge clk, 0);
•
REMOVAL is matched to $removal:
Table 11-10. Matching SDF REMOVAL to Verilog
SDF
(REMOVAL (negedge reset) (posedge clk)
(5))
Verilog
$removal(negedge reset, posedge clk, 0);
•
RECREM is matched to $recovery, $removal, and $recrem:
Table 11-11. Matching SDF RECREM to Verilog
SDF
(RECREM (negedge reset) (posedge clk)
(5) (5))
Verilog
$recovery(negedge reset, posedge clk, 0);
$removal(negedge reset, posedge clk, 0); (RECREM (negedge reset) (posedge clk)
(5) (5))
(RECREM (negedge reset) (posedge clk)
(5) (5))
$recrem(negedge reset, posedge clk, 0);
•
SKEW is matched to $skew:
SDF
Table 11-12. Matching SDF SKEW to Verilog
Verilog
(SKEW (posedge clk1) (posedge clk2) (5)) $skew(posedge clk1, posedge clk2, 0);
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$sdf_annotate
•
WIDTH is matched to $width:
Table 11-13. Matching SDF WIDTH to Verilog
SDF Verilog
(WIDTH (posedge clk) (5)) $width(posedge clk, 0);
•
PERIOD is matched to $period:
Table 11-14. Matching SDF PERIOD to Verilog
SDF Verilog
(PERIOD (posedge clk) (5)) $period(posedge clk, 0);
•
NOCHANGE is matched to $nochange:
SDF
Table 11-15. Matching SDF NOCHANGE to Verilog
Verilog
(NOCHANGE (negedge write) addr (5) (5)) $nochange(negedge write, addr, 0, 0);
Optional Edge Specifications
Timing check ports and path delay input ports can have optional edge specifications. The annotator uses the following rules to match edges:
•
A match occurs if the SDF port does not have an edge.
•
A match occurs if the specify port does not have an edge.
•
A match occurs if the SDF port edge is identical to the specify port edge.
•
A match occurs if explicit edge transitions in the specify port edge overlap with the SDF port edge.
These rules allow SDF annotation to take place even if there is a difference between the number of edge-specific constructs in the SDF file and the Verilog specify block. For example, the
Verilog specify block may contain separate setup timing checks for a falling and rising edge on data with respect to clock, while the SDF file may contain only a single setup check for both edges:
Table 11-16. Matching Verilog Timing Checks to SDF SETUP
SDF Verilog
(SETUP data (posedge clock) (5)) $setup(posedge data, posedge clk, 0);
(SETUP data (posedge clock) (5)) $setup(negedge data, posedge clk, 0);
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$sdf_annotate
In this case, the cell accommodates more accurate data than can be supplied by the tool that created the SDF file, and both timing checks correctly receive the same value.
Likewise, the SDF file may contain more accurate data than the model can accommodate.
SDF
Table 11-17. SDF Data May Be More Accurate Than Model
Verilog
(SETUP (posedge data) (posedge clock) (4)) $setup(data, posedge clk, 0);
(SETUP (negedge data) (posedge clock) (6)) $setup(data, posedge clk, 0);
In this case, both SDF constructs are matched and the timing check receives the value from the last one encountered.
Timing check edge specifiers can also use explicit edge transitions instead of posedge and negedge. However, the SDF file is limited to posedge and negedge. For example,
Table 11-18. Matching Explicit Verilog Edge Transitions to Verilog
SDF Verilog
(SETUP data (posedge clock) (5)) $setup(data, edge[01, 0x] clk, 0);
The explicit edge specifiers are 01, 0x, 10, 1x, x0, and x1. The set of [01, 0x, x1] is equivalent to posedge, while the set of [10, 1x, x0] is equivalent to negedge. A match occurs if any of the explicit edges in the specify port match any of the explicit edges implied by the SDF port.
Optional Conditions
Timing check ports and path delays can have optional conditions. The annotator uses the following rules to match conditions:
•
A match occurs if the SDF does not have a condition.
•
A match occurs for a timing check if the SDF port condition is semantically equivalent to the specify port condition.
•
A match occurs for a path delay if the SDF condition is lexically identical to the specify condition.
Timing check conditions are limited to very simple conditions, therefore the annotator can match the expressions based on semantics. For example,
Table 11-19. SDF Timing Check Conditions
SDF
(SETUP data (COND (reset!=1)
(posedge clock)) (5))
Verilog
$setup(data, posedge clk &&&
(reset==0),0);
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SDF for Mixed VHDL and Verilog Designs
The conditions are semantically equivalent and a match occurs. In contrast, path delay conditions may be complicated and semantically equivalent conditions may not match. For example,
Table 11-20. SDF Path Delay Conditions
SDF
(COND (r1 || r2) (IOPATH clk q (5)))
Verilog
if (r1 || r2) (clk => q) = 5; // matches
(COND (r1 || r2) (IOPATH clk q (5))) if (r2 || r1) (clk => q) = 5; // does not match
The annotator does not match the second condition above because the order of r1 and r2 are reversed.
Rounded Timing Values
The SDF TIMESCALE construct specifies time units of values in the SDF file. The annotator rounds timing values from the SDF file to the time precision of the module that is annotated. For example, if the SDF TIMESCALE is 1ns and a value of .016 is annotated to a path delay in a module having a time precision of 10ps (from the timescale directive), then the path delay receives a value of 20ps. The SDF value of 16ps is rounded to 20ps. Interconnect delays are rounded to the time precision of the module that contains the annotated MIPD.
SDF for Mixed VHDL and Verilog Designs
Annotation of a mixed VHDL and Verilog design is very flexible. VHDL VITAL cells and
Verilog cells can be annotated from the same SDF file. This flexibility is available only by using the simulator’s SDF command-line options. The Verilog $sdf_annotate system task can annotate Verilog cells only. See the vsim command for more information on SDF commandline options.
Interconnect Delays
An interconnect delay represents the delay from the output of one device to the input of another.
ModelSim can model single interconnect delays or multisource interconnect delays for Verilog,
VHDL/VITAL, or mixed designs. See the vsim command for more information on the relevant command-line arguments.
Timing checks are performed on the interconnect delayed versions of input ports. This may result in misleading timing constraint violations, because the ports may satisfy the constraint while the delayed versions may not. If the simulator seems to report incorrect violations, be sure to account for the effect of interconnect delays.
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Disabling Timing Checks
Disabling Timing Checks
ModelSim offers a number of options for disabling timing checks on a "global" or individual basis. The table below provides a summary of those options. See the command and argument descriptions in the Reference Manual for more details.
Table 11-21. Disabling Timing Checks
Command and argument Effect vlog +notimingchecks vlog +nospecify vsim +no_neg_tchk
disables timing check system tasks for all instances in the specified Verilog design disables specify path delays and timing checks for all instances in the specified Verilog design disables negative timing check limits by setting them to zero for all instances in the specified design
vsim +no_notifier vsim +no_tchk_msg vsim +notimingchecks vsim +nospecify
disables the toggling of the notifier register argument of the timing check system tasks for all instances in the specified design disables error messages issued by timing check system tasks when timing check violations occur for all instances in the specified design disables Verilog and VITAL timing checks for all instances in the specified design disables specify path delays and timing checks for all instances in the specified design
Troubleshooting
Specifying the Wrong Instance
By far, the most common mistake in SDF annotation is to specify the wrong instance to the simulator’s SDF options. The most common case is to leave off the instance altogether, which is the same as selecting the top-level design unit. This is generally wrong because the instance paths in the SDF are relative to the ASIC or FPGA model, which is usually instantiated under a top-level testbench. See
Instance Specification for an example.
A common example for both VHDL and Verilog testbenches is provided below. For simplicity, the test benches do nothing more than instantiate a model that has no ports.
VHDL Testbench
entity testbench is end;
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Troubleshooting
architecture only of testbench is component myasic end component; begin dut : myasic; end;
Verilog Testbench
module testbench; myasic dut(); endmodule
The name of the model is myasic and the instance label is dut. For either testbench, an appropriate simulator invocation might be:
vsim -sdfmax /testbench/dut=myasic.sdf testbench
Optionally, you can leave off the name of the top-level:
vsim -sdfmax /dut=myasic.sdf testbench
The important thing is to select the instance for which the SDF is intended. If the model is deep within the design hierarchy, an easy way to find the instance name is to first invoke the simulator without SDF options, view the structure pane, navigate to the model instance, select it, and enter the environment command. This command displays the instance name that should be used in the SDF command-line option.
Mistaking a Component or Module Name for an Instance
Label
Another common error is to specify the component or module name rather than the instance label. For example, the following invocation is wrong for the above testbenches:
vsim -sdfmax /testbench/myasic=myasic.sdf testbench
This results in the following error message:
** Error (vsim-SDF-3250) myasic.sdf(0):
Failed to find INSTANCE ’/testbench/myasic’.
Forgetting to Specify the Instance
If you leave off the instance altogether, then the simulator issues a message for each instance path in the SDF that is not found in the design. For example,
vsim -sdfmax myasic.sdf testbench
Results in:
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Troubleshooting
** Error (vsim-SDF-3250) myasic.sdf(0):
Failed to find INSTANCE ’/testbench/u1’
** Error (vsim-SDF-3250) myasic.sdf(0):
Failed to find INSTANCE ’/testbench/u2’
** Error (vsim-SDF-3250) myasic.sdf(0):
Failed to find INSTANCE ’/testbench/u3’
** Error (vsim-SDF-3250) myasic.sdf(0):
Failed to find INSTANCE ’/testbench/u4’
** Error (vsim-SDF-3250) myasic.sdf(0):
Failed to find INSTANCE ’/testbench/u5’
** Warning (vsim-SDF-3432) myasic.sdf:
This file is probably applied to the wrong instance.
** Warning (vsim-SDF-3432) myasic.sdf:
Ignoring subsequent missing instances from this file.
After annotation is done, the simulator issues a summary of how many instances were not found and possibly a suggestion for a qualifying instance:
** Warning (vsim-SDF-3440) myasic.sdf:
Failed to find any of the 358 instances from this file.
** Warning (vsim-SDF-3442) myasic.sdf:
Try instance ’/testbench/dut’. It contains all instance paths from this file.
The simulator recommends an instance only if the file was applied to the top-level and a qualifying instance is found one level down.
Also see
Resolving Errors for specific VHDL VITAL SDF troubleshooting.
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Chapter 12
Value Change Dump (VCD) Files
This chapter describes how to use VCD files in ModelSim. The VCD file format is specified in the IEEE 1364 standard. It is an ASCII file containing header information, variable definitions, and variable value changes.
VCD is in common use for Verilog designs, and is controlled by VCD system task calls in the
Verilog source code. ModelSim provides command equivalents for these system tasks and extends VCD support to VHDL designs. The ModelSim commands can be used on VHDL,
Verilog, or mixed designs.
If you need vendor-specific ASIC design-flow documentation that incorporates VCD, please contact your ASIC vendor.
Creating a VCD File
There are two flows in ModelSim for creating a VCD file. One flow produces a four-state VCD file with variable changes in 0, 1, x, and z with no strength information; the other produces an extended VCD file with variable changes in all states and strength information and port driver data.
Both flows will also capture port driver changes unless filtered out with optional command-line arguments.
Flow for Four-State VCD File
First, compile and load the design:
% cd ~/modeltech/examples/misc
% vlib work
% vlog counter.v tcounter.v
% vsim test_counter
Next, with the design loaded, specify the VCD file name with the vcd file command and add objects to the file with the vcd add command:
VSIM 1> vcd file myvcdfile.vcd
VSIM 2> vcd add /test_counter/dut/*
VSIM 3> run
VSIM 4> quit -f
There will now be a VCD file in the working directory.
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Using Extended VCD as Stimulus
Flow for Extended VCD File
First, compile and load the design:
% cd ~/modeltech/examples/misc
% vlib work
% vlog counter.v tcounter.v
% vsim test_counter
Next, with the design loaded, specify the VCD file name and objects to add with the
vcd dumpports
command:
VSIM 1> vcd dumpports -file myvcdfile.vcd /test_counter/dut/*
VSIM 3> run
VSIM 4> quit -f
There will now be an extended VCD file called myvcdfile.vcd in the working directory.
Note
There is an internal limit to the number of port driver changes that can be created with the
vcd dumpports
command. If that limit is reached, use the
vcd add
command with the
-dumpports option to create additional port driver changes.
By default ModelSim uses strength ranges for resolving conflicts as specified by IEEE
1364-2005. You can ignore strength ranges using the -no_strength_range argument to the vcd dumpports command. See
for more details.
Case Sensitivity
VHDL is not case sensitive so ModelSim converts all signal names to lower case when it produces a VCD file. Conversely, Verilog designs are case sensitive so ModelSim maintains case when it produces a VCD file.
Using Extended VCD as Stimulus
You can use an extended VCD file as stimulus to re-simulate your design. There are two ways to do this: 1) simulate the top level of a design unit with the input values from an extended VCD file; and 2) specify one or more instances in a design to be replaced with the output values from the associated VCD file.
Simulating with Input Values from a VCD File
When simulating with inputs from an extended VCD file, you can simulate only one design unit at a time. In other words, you can apply the VCD file inputs only to the top level of the design unit for which you captured port data.
The general procedure includes two steps:
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Using Extended VCD as Stimulus
1. Create a VCD file for a single design unit using the vcd dumpports command.
2. Resimulate the single design unit using the -vcdstim argument to vsim . Note that
-vcdstim works only with VCD files that were created by a ModelSim simulation.
Example 12-1. Verilog Counter
First, create the VCD file for the single instance using vcd dumpports:
% cd ~/modeltech/examples/misc
% vlib work
% vlog counter.v tcounter.v
% vsim test_counter
VSIM 1> vcd dumpports -file counter.vcd /test_counter/dut/*
VSIM 2> run
VSIM 3> quit -f
Next, rerun the counter without the testbench, using the -vcdstim argument:
% vsim -vcdstim counter.vcd counter
VSIM 1> add wave /*
VSIM 2> run 200
Example 12-2. VHDL Adder
First, create the VCD file using vcd dumpports:
% cd ~/modeltech/examples/misc
% vlib work
% vcom gates.vhd adder.vhd stimulus.vhd
% vsim testbench2
VSIM 1> vcd dumpports -file addern.vcd /testbench2/uut/*
VSIM 2> run 1000
VSIM 3> quit -f
Next, rerun the adder without the testbench, using the -vcdstim argument:
% vsim -vcdstim addern.vcd addern -gn=8 -do "add wave /*; run 1000"
Example 12-3. Mixed-HDL Design
First, create three VCD files, one for each module:
% cd ~/modeltech/examples/tutorials/mixed/projects
% vlib work
% vlog cache.v memory.v proc.v
% vcom util.vhd set.vhd top.vhd
% vsim top
VSIM 1> vcd dumpports -file proc.vcd /top/p/*
VSIM 2> vcd dumpports -file cache.vcd /top/c/*
VSIM 3> vcd dumpports -file memory.vcd /top/m/*
VSIM 4> run 1000
VSIM 5> quit -f
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Using Extended VCD as Stimulus
Next, rerun each module separately, using the captured VCD stimulus:
% vsim -vcdstim proc.vcd proc -do "add wave /*; run 1000"
VSIM 1> quit -f
% vsim -vcdstim cache.vcd cache -do "add wave /*; run 1000"
VSIM 1> quit -f
% vsim -vcdstim memory.vcd memory -do "add wave /*; run 1000"
VSIM 1> quit -f
Replacing Instances with Output Values from a VCD File
Replacing instances with output values from a VCD file lets you simulate without the instance’s source or even the compiled object. The general procedure includes two steps:
1. Create VCD files for one or more instances in your design using the vcd dumpports command. If necessary, use the -vcdstim switch to handle port order problems (see below).
2. Re-simulate your design using the -vcdstim <instance>=<filename> argument to vsim .
Note that this works only with VCD files that were created by a ModelSim simulation.
Example 12-4. Replacing Instances
In the following example, the three instances /top/p, /top/c, and /top/m are replaced in simulation by the output values found in the corresponding VCD files.
First, create VCD files for all instances you want to replace:
vcd dumpports -vcdstim -file proc.vcd /top/p/* vcd dumpports -vcdstim -file cache.vcd /top/c/* vcd dumpports -vcdstim -file memory.vcd /top/m/* run 1000
Next, simulate your design and map the instances to the VCD files you created:
vsim top -vcdstim /top/p=proc.vcd -vcdstim /top/c=cache.vcd
-vcdstim /top/m=memory.vcd
Port Order Issues
The -vcdstim argument to the vcd dumpports command ensures the order that port names appear in the VCD file matches the order that they are declared in the instance’s module or entity declaration. Consider the following module declaration: module proc(clk, addr, data, rw, strb, rdy); input clk, rdy; output addr, rw, strb; inout data;
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VCD Commands and VCD Tasks
The order of the ports in the module line (clk, addr, data, ...) does not match the order of those ports in the input, output, and inout lines (clk, rdy, addr, ...). In this case the -vcdstim argument to the vcd dumpports command needs to be used.
In cases where the order is the same, you do not need to use the -vcdstim argument to vcd
dumpports. Also, module declarations of the form: module proc(input clk, output addr, inout data, ...) do not require use of the argument.
VCD Commands and VCD Tasks
ModelSim VCD commands map to IEEE Std 1364 VCD system tasks and appear in the VCD file along with the results of those commands. The table below maps the VCD commands to their associated tasks.
Table 12-1. VCD Commands and SystemTasks
VCD commands VCD system tasks
vcd add vcd checkpoint
$dumpvars
$dumpall vcd file vcd flush vcd limit vcd off vcd on
$dumpfile
$dumpflush
$dumplimit
$dumpoff
$dumpon
ModelSim also supports extended VCD (dumpports system tasks). The table below maps the
VCD dumpports commands to their associated tasks.
Table 12-2. VCD Dumpport Commands and System Tasks
VCD dumpports commands VCD system tasks
vcd dumpports vcd dumpportsall
$dumpports
$dumpportsall vcd dumpportsflush vcd dumpportslimit vcd dumpportsoff vcd dumpportson
$dumpportsflush
$dumpportslimit
$dumpportsoff
$dumpportson
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VCD File from Source To Output
ModelSim supports multiple VCD files. This functionality is an extension of the IEEE Std 1364 specification. The tasks behave the same as the IEEE equivalent tasks such as $dumpfile,
$dumpvar, etc. The difference is that $fdumpfile can be called multiple times to create more than one VCD file, and the remaining tasks require a filename argument to associate their actions with a specific file.
Table 12-3. VCD Commands and System Tasks for Multiple VCD Files
VCD commands VCD system tasks
vcd add -file <filename> vcd checkpoint <filename>
$fdumpvars
$fdumpall vcd files <filename> vcd flush <filename> vcd limit <filename> vcd off <filename> vcd on <filename>
$fdumpfile
$fdumpflush
$fdumplimit
$fdumpoff
$fdumpon
Compressing Files with VCD Tasks
ModelSim can produce compressed VCD files using the gzip compression algorithm. Since we cannot change the syntax of the system tasks, we act on the extension of the output file name. If you specify a .gz extension on the filename, ModelSim will compress the output.
VCD File from Source To Output
The following example shows the VHDL source, a set of simulator commands, and the resulting VCD output.
VHDL Source Code
The design is a simple shifter device represented by the following VHDL source code:
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library IEEE; use IEEE.STD_LOGIC_1164.all; entity SHIFTER_MOD is port (CLK, RESET, data_in : IN STD_LOGIC;
Q : INOUT STD_LOGIC_VECTOR(8 downto 0));
END SHIFTER_MOD ; architecture RTL of SHIFTER_MOD is begin process (CLK,RESET) begin if (RESET = '1') then
Q <= (others => '0') ; elsif (CLK'event and CLK = '1') then
Q <= Q(Q'left - 1 downto 0) & data_in ; end if ; end process ; end ;
Value Change Dump (VCD) Files
VCD File from Source To Output
VCD Simulator Commands
At simulator time zero, the designer executes the following commands:
vcd file output.vcd
vcd add -r * force reset 1 0 force data_in 0 0 force clk 0 0 run 100 force clk 1 0, 0 50 -repeat 100 run 100 vcd off force reset 0 0 force data_in 1 0 run 100 vcd on run 850 force reset 1 0 run 50 vcd checkpoint quit -sim
VCD Output
The VCD file created as a result of the preceding scenario would be called output.vcd. The following pages show how it would look.
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x' x( x) x* x# x$ x% x& x+ x,
0'
0(
0)
0*
0+
0,
$end
#100
1!
#150
0!
#200
1!
$dumpoff x!
x"
$date
Thu Sep 18 11:07:43 2003
$end
$version
ModelSim Version 6.1
$end
$timescale
1ns
$end
$scope module shifter_mod $end
$var wire 1 ! clk $end
$var wire 1 " reset $end
$var wire 1 # data_in $end
$var wire 1 $ q [8] $end
$var wire 1 % q [7] $end
$var wire 1 & q [6] $end
$var wire 1 ' q [5] $end
$var wire 1 ( q [4] $end
$var wire 1 ) q [3] $end
$var wire 1 * q [2] $end
$var wire 1 + q [1] $end
$var wire 1 , q [0] $end
$upscope $end
$enddefinitions $end
0#
0$
0%
0&
#0
$dumpvars
0!
1"
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1'
#850
0!
#900
1!
1&
#950
0!
0!
#700
1!
1(
#750
0!
#800
1!
#1000
1!
1%
#1050
0!
#1100
1!
1$
#1150
0!
1!
1*
#550
0!
#600
1!
1)
#650
#350
0!
#400
1!
1+
#450
0!
#500
0&
0'
0(
0)
0*
0+
1,
$end
0"
1#
0$
0%
$end
#300
$dumpon
1!
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0(
0)
0*
0+
0$
0%
0&
0'
0,
$end
0)
0(
0'
0&
1"
0,
0+
0*
0%
0$
#1200
1!
$dumpall
1!
1"
1#
Capturing Port Driver Data
Some ASIC vendors’ toolkits read a VCD file format that provides details on port drivers. This information can be used, for example, to drive a tester. See the ASIC vendor’s documentation for toolkit specific information.
In ModelSim use the vcd dumpports command to create a VCD file that captures port driver data. Each time an external or internal port driver changes values, a new value change is recorded in the VCD file with the following format:
p<state> <0 strength> <1 strength> <identifier_code>
Driver States
The driver states are recorded as TSSI states if the direction is known, as detailed in this table:
Table 12-4. Driver States
Input (testfixture) Output (dut)
D low
U high
L low
H high
N unknown
Z tri-state
X unknown
T tri-state
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Table 12-4. Driver States (cont.)
Input (testfixture) Output (dut)
d low (two or more drivers active) u high (two or more drivers active) l low (two or more drivers active) h high (two or more drivers active)
If the direction is unknown, the state will be recorded as one of the following:
Table 12-5. State When Direction is Unknown
Unknown direction
0 low (both input and output are driving low)
1 high (both input and output are driving high)
? unknown (both input and output are driving unknown)
F three-state (input and output unconnected)
A unknown (input driving low and output driving high) a unknown (input driving low and output driving unknown)
B unknown (input driving high and output driving low) b unknown (input driving high and output driving unknown)
C unknown (input driving unknown and output driving low) c unknown (input driving unknown and output driving high) f unknown (input and output three-stated)
Driver Strength
The recorded 0 and 1 strength values are based on Verilog strengths:
Strength
Table 12-6. Driver Strength
VHDL std_logic mappings
0 highz
1 small
’Z’
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Table 12-6. Driver Strength (cont.)
Strength VHDL std_logic mappings
2 medium
3 weak
4 large
5 pull
6 strong
7 supply
’W’,’H’,’L’
’U’,’X’,’0’,’1’,’-’
Identifier Code
The <identifier_code> is an integer preceded by < that starts at zero and is incremented for each port in the order the ports are specified. Also, the variable type recorded in the VCD header is
"port".
Resolving Values
The resolved values written to the VCD file depend on which options you specify when creating the file.
Default Behavior
By default ModelSim generates output according to IEEE 1364-2005. The standard states that the values 0 (both input and output are active with value 0) and 1 (both input and output are active with value 1) are conflict states. The standard then defines two strength ranges:
•
Strong: strengths 7, 6, and 5
•
Weak: strengths 4, 3, 2, 1
The rules for resolving values are as follows:
•
If the input and output are driving the same value with the same range of strength, the resolved value is 0 or 1, and the strength is the stronger of the two.
•
If the input is driving a strong strength and the output is driving a weak strength, the resolved value is D, d, U or u, and the strength is the strength of the input.
•
If the input is driving a weak strength and the output is driving a strong strength, the resolved value is L, l, H or h, and the strength is the strength of the output.
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Ignoring Strength Ranges
You may wish to ignore strength ranges and have ModelSim handle each strength separately.
Any of the following options will produce this behavior:
•
Use the -no_strength_range argument to the vcd dumpports command
•
Use an optional argument to $dumpports (see
Extended $dumpports Syntax below)
•
Use the +dumpports+no_strength_range argument to vsim command
In this situation, ModelSim reports strengths for both the zero and one components of the value if the strengths are the same. If the strengths are different, ModelSim reports only the “winning” strength. In other words, the two strength values either match (e.g., pA 5 5 !) or the winning strength is shown and the other is zero (e.g., pH 0 5 !).
Extended $dumpports Syntax
ModelSim extends the $dumpports system task in order to support exclusion of strength ranges.
The extended syntax is as follows:
$dumpports (scope_list, file_pathname, ncsim_file_index, file_format)
The nc_sim_index argument is required yet ignored by ModelSim. It is required only to be compatible with NCSim’s argument list.
The file_format argument accepts the following values or an ORed combination thereof (see examples below):
4
8
0
2
Table 12-7. Values for file_format Argument
File_format value Meaning
Ignore strength range
Use strength ranges; produces IEEE 1364-compliant behavior
Compress the EVCD output
Include port direction information in the EVCD file header; same as using -direction argument to vcd
dumpports
Here are some examples:
// ignore strength range
$dumpports(top, "filename", 0, 0)
// compress and ignore strength range
$dumpports(top, "filename", 0, 4)
// print direction and ignore strength range
$dumpports(top, "filename", 0, 8)
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// compress, print direction, and ignore strength range
$dumpports(top, "filename", 0, 12)
Example 12-5. VCD Output from vcd dumpports
This example demonstrates how vcd dumpports resolves values based on certain combinations of driver values and strengths and whether or not you use strength ranges.
is sample driver data.
time
0
100
200
300
900 1
27400 1
27500 1
27600 1
0
0
0
0
Table 12-8. Sample Driver Data in value out value in strength value
(range) out strength value
(range)
0
0
0
0
7 (strong)
6 (strong)
5 (strong)
4 (weak)
7 (strong)
7 (strong)
7 (strong)
7 (strong)
0
1
1
1
6 (strong)
5 (strong)
4 (weak)
3 (weak)
7 (strong)
4 (weak)
4 (weak)
4 (weak)
Given the driver data above and use of 1364 strength ranges, here is what the VCD file output would look like:
#0 p0 7 0 <0
#100 p0 7 0 <0
#200 p0 7 0 <0
#300 pL 7 0 <0
#900 pB 7 0 <0
#27400 pU 0 5 <0
#27500 p1 0 4 <0
#27600 p1 0 4 <0
Here is what the output would look like if you ignore strength ranges:
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#0 p0 7 0 <0
#100 pL 7 0 <0
#200 pL 7 0 <0
#300 pL 7 0 <0
#900 pL 7 0 <0
#27400 pU 0 5 <0
#27500 p1 0 4 <0
#27600 pH 0 4 <0
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Chapter 13
Tcl and Macros (DO Files)
Tcl is a scripting language for controlling and extending ModelSim. Within ModelSim you can develop implementations from Tcl scripts without the use of C code. Because Tcl is interpreted, development is rapid; you can generate and execute Tcl scripts on the fly without stopping to recompile or restart ModelSim. In addition, if ModelSim does not provide the command you need, you can use Tcl to create your own commands.
Tcl Features
Using Tcl with ModelSim gives you these features:
• command history (like that in C shells)
• full expression evaluation and support for all C-language operators
• a full range of math and trig functions
• support of lists and arrays
• regular expression pattern matching
• procedures
• the ability to define your own commands
• command substitution (that is, commands may be nested)
• robust scripting language for macros
Tcl References
Two books about Tcl are Tcl and the Tk Toolkit by John K. Ousterhout, published by Addison-
Wesley Publishing Company, Inc., and Practical Programming in Tcl and Tk by Brent Welch published by Prentice Hall. You can also consult the following online references:
•
Select Help > Tcl Man Pages.
Tcl Commands
For complete information on Tcl commands, select Help > Tcl Man Pages. Also see
GUI Preferences for information on Tcl preference variables.
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Tcl Command Syntax
ModelSim command names that conflict with Tcl commands have been renamed or have been replaced by Tcl commands. See the list below:
Previous ModelSim command
continue format list | wave if list nolist | nowave set source wave
Table 13-1.
Command changed to (or replaced by)
run with the -continue option write format with either list or wave specified replaced by the Tcl if command, see
add list delete with either list or wave specified replaced by the Tcl set command vsource add wave
Tcl Command Syntax
The following eleven rules define the syntax and semantics of the Tcl language. Additional details on
1. A Tcl script is a string containing one or more commands. Semi-colons and newlines are command separators unless quoted as described below. Close brackets ("]") are command terminators during command substitution (see below) unless quoted.
2. A command is evaluated in two steps. First, the Tcl interpreter breaks the command into words and performs substitutions as described below. These substitutions are performed in the same way for all commands. The first word is used to locate a command procedure to carry out the command, then all of the words of the command are passed to the command procedure. The command procedure is free to interpret each of its words in any way it likes, such as an integer, variable name, list, or Tcl script. Different commands interpret their words differently.
3. Words of a command are separated by white space (except for newlines, which are command separators).
4. If the first character of a word is a double-quote (") then the word is terminated by the next double-quote character. If semi-colons, close brackets, or white space characters
(including newlines) appear between the quotes then they are treated as ordinary characters and included in the word. Command substitution, variable substitution, and backslash substitution are performed on the characters between the quotes as described below. The double-quotes are not retained as part of the word.
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5. If the first character of a word is an open brace ({) then the word is terminated by the matching close brace (}). Braces nest within the word: for each additional open brace there must be an additional close brace (however, if an open brace or close brace within the word is quoted with a backslash then it is not counted in locating the matching close brace). No substitutions are performed on the characters between the braces except for backslash-newline substitutions described below, nor do semi-colons, newlines, close brackets, or white space receive any special interpretation. The word will consist of exactly the characters between the outer braces, not including the braces themselves.
6. If a word contains an open bracket ([) then Tcl performs command substitution. To do this it invokes the Tcl interpreter recursively to process the characters following the open bracket as a Tcl script. The script may contain any number of commands and must be terminated by a close bracket (]). The result of the script (i.e. the result of its last command) is substituted into the word in place of the brackets and all of the characters between them. There may be any number of command substitutions in a single word.
Command substitution is not performed on words enclosed in braces.
7. If a word contains a dollar-sign ($) then Tcl performs variable substitution: the dollarsign and the following characters are replaced in the word by the value of a variable.
Variable substitution may take any of the following forms: o o
$name
Name is the name of a scalar variable; the name is terminated by any character that isn't a letter, digit, or underscore.
$name(index)
Name gives the name of an array variable and index gives the name of an element within that array. Name must contain only letters, digits, and underscores. Command substitutions, variable substitutions, and backslash substitutions are performed on the characters of index.
o
${name}
Name is the name of a scalar variable. It may contain any characters whatsoever except for close braces.
There may be any number of variable substitutions in a single word. Variable substitution is not performed on words enclosed in braces.
8. If a backslash (\) appears within a word then backslash substitution occurs. In all cases but those described below the backslash is dropped and the following character is treated as an ordinary character and included in the word. This allows characters such as double quotes, close brackets, and dollar signs to be included in words without
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triggering special processing. The following table lists the backslash sequences that are handled specially, along with the value that replaces each sequence.
Sequence
\a
\b
\f
\n
\r
\t
\v
\<newline>whiteSpace
Table 13-2. Tcl Backslash Sequences
Value
Audible alert (bell) (0x7)
Backspace (0x8)
Form feed (0xc).
Newline (0xa)
Carriage-return (0xd)
Tab (0x9)
\\
\ooo
\xhh
Vertical tab (0xb)
A single space character replaces the backslash, newline, and all spaces and tabs after the newline. This backslash sequence is unique in that it is replaced in a separate prepass before the command is actually parsed. This means that it will be replaced even when it occurs between braces, and the resulting space will be treated as a word separator if it isn't in braces or quotes.
Backslash ("\")
The digits ooo (one, two, or three of them) give the octal value of the character.
The hexadecimal digits hh give the hexadecimal value of the character. Any number of digits may be present.
Backslash substitution is not performed on words enclosed in braces, except for backslash-newline as described above.
9. If a hash character (#) appears at a point where Tcl is expecting the first character of the first word of a command, then the hash character and the characters that follow it, up through the next newline, are treated as a comment and ignored. The comment character only has significance when it appears at the beginning of a command.
10. Each character is processed exactly once by the Tcl interpreter as part of creating the words of a command. For example, if variable substitution occurs then no further substitutions are performed on the value of the variable; the value is inserted into the word verbatim. If command substitution occurs then the nested command is processed entirely by the recursive call to the Tcl interpreter; no substitutions are performed before making the recursive call and no additional substitutions are performed on the result of the nested script.
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11. Substitutions do not affect the word boundaries of a command. For example, during variable substitution the entire value of the variable becomes part of a single word, even if the variable's value contains spaces.
If Command Syntax
The Tcl if command executes scripts conditionally. Note that in the syntax below the question mark (?) indicates an optional argument.
Syntax if expr1 ?then? body1 elseif expr2 ?then? body2 elseif ... ?else? ?bodyN?
Description
The if command evaluates expr1 as an expression. The value of the expression must be a boolean (a numeric value, where 0 is false and anything else is true, or a string value such as
true or yes for true and false or no for false); if it is true then body1 is executed by passing it to the Tcl interpreter. Otherwise expr2 is evaluated as an expression and if it is true then body2 is executed, and so on. If none of the expressions evaluates to true then bodyN is executed. The
then and else arguments are optional "noise words" to make the command easier to read. There may be any number of elseif clauses, including zero. BodyN may also be omitted as long as else is omitted too. The return value from the command is the result of the body script that was executed, or an empty string if none of the expressions was non-zero and there was no bodyN.
Command Substitution
Placing a command in square brackets ([ ]) will cause that command to be evaluated first and its results returned in place of the command. An example is:
set a 25 set b 11 set c 3 echo "the result is [expr ($a + $b)/$c]"
will output:
"the result is 12"
This feature allows VHDL variables and signals, and Verilog nets and registers to be accessed using:
[examine -<radix> name]
The %name substitution is no longer supported. Everywhere %name could be used, you now can use [examine -value -<radix> name] which allows the flexibility of specifying command options. The radix specification is optional.
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Command Separator
A semicolon character (;) works as a separator for multiple commands on the same line. It is not required at the end of a line in a command sequence.
Multiple-Line Commands
With Tcl, multiple-line commands can be used within macros and on the command line. The command line prompt will change (as in a C shell) until the multiple-line command is complete.
In the example below, note the way the opening brace ’{’ is at the end of the if and else lines.
This is important because otherwise the Tcl scanner won't know that there is more coming in the command and will try to execute what it has up to that point, which won't be what you intend.
if { [exa sig_a] == "0011ZZ"} { echo "Signal value matches" do macro_1.do
} else { echo "Signal value fails" do macro_2.do
}
Evaluation Order
An important thing to remember when using Tcl is that anything put in braces ({}) is not evaluated immediately. This is important for if-then-else statements, procedures, loops, and so forth.
Tcl Relational Expression Evaluation
When you are comparing values, the following hints may be useful:
•
Tcl stores all values as strings, and will convert certain strings to numeric values when appropriate. If you want a literal to be treated as a numeric value, don't quote it.
if {[exa var_1] == 345}...
The following will also work: if {[exa var_1] == "345"}...
•
However, if a literal cannot be represented as a number, you must quote it, or Tcl will give you an error. For instance: if {[exa var_2] == 001Z}...
will give an error.
if {[exa var_2] == "001Z"}...
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will work okay.
•
Don't quote single characters in single quotes: if {[exa var_3] == 'X'}...
will give an error if {[exa var_3] == "X"}...
will work okay.
•
For the equal operator, you must use the C operator (==). For not-equal, you must use the C operator (!=).
Variable Substitution
When a $<var_name> is encountered, the Tcl parser will look for variables that have been defined either by ModelSim or by you, and substitute the value of the variable.
Note
Tcl is case sensitive for variable names.
To access environment variables, use the construct:
$env(<var_name>) echo My user name is $env(USER)
Environment variables can also be set using the env array:
set env(SHELL) /bin/csh
See
Simulator State Variables for more information about ModelSim-defined variables.
System Commands
To pass commands to the UNIX shell or DOS window, use the Tcl exec command:
echo The date is [exec date]
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List Processing
List Processing
In Tcl a "list" is a set of strings in curly braces separated by spaces. Several Tcl commands are available for creating lists, indexing into lists, appending to lists, getting the length of lists and shifting lists. These commands are:
Table 13-3. Tcl List Commands
Command syntax
lappend var_name val1 val2 ...
Description
appends val1, val2, etc. to list var_name
lindex list_name index returns the index-th element of list_name; the first element is 0
linsert list_name index val1 val2 ...
inserts val1, val2, etc. just before the index-th element of list_name
list val1, val2 ...
llength list_name
lrange list_name first last returns a Tcl list consisting of val1, val2, etc.
returns the number of elements in list_name
lreplace list_name first last val1, val2, ...
returns a sublist of list_name, from index first to index last; first or last may be "end", which refers to the last element in the list replaces elements first through last with val1, val2, etc.
Two other commands, lsearch and lsort, are also available for list manipulation. See the Tcl man pages (Help > Tcl Man Pages) for more information on these commands.
Simulator Tcl Commands
These additional commands enhance the interface between Tcl and ModelSim. Only brief descriptions are provided here; for more information and command syntax see the Reference
Manual.
Command
alias find lshift lsublist
Table 13-4. Simulator-Specific Tcl Commands
Description
creates a new Tcl procedure that evaluates the specified commands; used to create a user-defined alias locates incrTcl classes and objects takes a Tcl list as argument and shifts it in-place one place to the left, eliminating the 0th element returns a sublist of the specified Tcl list that matches the specified Tcl glob pattern
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Command
printenv
Tcl and Macros (DO Files)
Simulator Tcl Time Commands
Table 13-4. Simulator-Specific Tcl Commands
Description
echoes to the Transcript pane the current names and values of all environment variables
Simulator Tcl Time Commands
ModelSim Tcl time commands make simulator-time-based values available for use within other
Tcl procedures.
Time values may optionally contain a units specifier where the intervening space is also optional. If the space is present, the value must be quoted (e.g. 10ns, "10 ns"). Time values without units are taken to be in the UserTimeScale. Return values are always in the current
Time Scale Units. All time values are converted to a 64-bit integer value in the current Time
Scale. This means that values smaller than the current Time Scale will be truncated to 0.
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Conversions
Table 13-5. Tcl Time Conversion Commands
Description
Command
intToTime <intHi32> <intLo32> converts two 32-bit pieces (high and low order) into a 64-bit quantity (Time in
ModelSim is a 64-bit integer)
RealToTime <real> scaleTime <time> <scaleFactor> converts a <real> number to a 64-bit integer in the current Time Scale returns the value of <time> multiplied by the <scaleFactor> integer
Relations
Table 13-6. Tcl Time Relation Commands
Description
Command
eqTime <time> <time> evaluates for equal neqTime <time> <time> gtTime <time> <time> evaluates for not equal evaluates for greater than gteTime <time> <time> ltTime <time> <time> lteTime <time> <time> evaluates for greater than or equal evaluates for less than evaluates for less than or equal
All relation operations return 1 or 0 for true or false respectively and are suitable return values for TCL conditional expressions. For example, if {[eqTime $Now 1750ns]} {
...
}
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Arithmetic
Table 13-7. Tcl Time Arithmetic Commands
Command
Description
addTime <time> <time> divTime <time> <time> add time
64-bit integer divide mulTime <time> <time> subTime <time> <time>
64-bit integer multiply subtract time
Tcl Examples
This is an example of using the Tcl while loop to copy a list from variable a to variable b, reversing the order of the elements along the way: set b [list] set i [expr {[llength $a] - 1}] while {$i >= 0} { lappend b [lindex $a $i] incr i -1
}
This example uses the Tcl for command to copy a list from variable a to variable b, reversing the order of the elements along the way: set b [list] for {set i [expr {[llength $a] - 1}]} {$i >= 0} {incr i -1} { lappend b [lindex $a $i]
}
This example uses the Tcl foreach command to copy a list from variable a to variable b, reversing the order of the elements along the way (the foreach command iterates over all of the elements of a list): set b [list] foreach i $a { set b [linsert $b 0 $i] }
This example shows a list reversal as above, this time aborting on a particular element using the
Tcl break command: set b [list] foreach i $a { if {$i = "ZZZ"} break set b [linsert $b 0 $i]
}
This example is a list reversal that skips a particular element by using the Tcl continue command:
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set b [list] foreach i $a { if {$i = "ZZZ"} continue set b [linsert $b 0 $i]
}
The next example works in UNIX only. In a Windows environment, the Tcl exec command will execute compiled files only, not system commands.) The example shows how you can access system information and transfer it into VHDL variables or signals and Verilog nets or registers.
When a particular HDL source breakpoint occurs, a Tcl function is called that gets the date and time and deposits it into a VHDL signal of type STRING. If a particular environment variable
(DO_ECHO) is set, the function also echoes the new date and time to the transcript file by examining the VHDL variable.
(in VHDL source): signal datime : string(1 to 28) := " ";# 28 spaces
(on VSIM command line or in macro): proc set_date {} { global env set do_the_echo [set env(DO_ECHO)] set s [clock format [clock seconds]] force -deposit datime $s if {do_the_echo} { echo "New time is [examine -value datime]"
}
} bp src/waveadd.vhd 133 {set_date; continue}
--sets the breakpoint to call set_date
This next example shows a complete Tcl script that restores multiple Wave windows to their state in a previous simulation, including signals listed, geometry, and screen position. It also adds buttons to the Main window toolbar to ease management of the wave files.
## This file contains procedures to manage multiple wave files.
## Source this file from the command line or as a startup script.
## source <path>/wave_mgr.tcl
## add_wave_buttons
## Add wave management buttons to the main toolbar (new, save and load)
## new_wave
## Dialog box creates a new wave window with the user provided name
## named_wave <name>
## Creates a new wave window with the specified title
## save_wave <file-root>
## Saves name, window location and contents for all open windows
## wave windows
## Creates <file-root><n>.do file for each window where <n> is 1
## to the number of windows. Default file-root is "wave". Also
## creates windowSet.do file that contains title and geometry info.
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## load_wave <file-root>
## Opens and loads wave windows for all files matching <fileroot><n>.do
## where <n> are the numbers from 1-9. Default <file-root> is "wave".
## Also runs windowSet.do file if it exists.
## Add wave management buttons to the main toolbar proc add_wave_buttons {} {
_add_menu main controls right SystemMenu SystemWindowFrame {Load Waves} \ load_wave
_add_menu main controls right SystemMenu SystemWindowFrame {Save Waves} \ save_wave
_add_menu main controls right SystemMenu SystemWindowFrame {New Wave} \ new_wave
}
## Simple Dialog requests name of new wave window. Defaults to Wave<n> proc new_wave {} { global vsimPriv set defaultName "Wave[llength $vsimPriv(WaveWindows)]" set windowName [GetValue . "Create Named Wave Window:" $defaultName ] if {$windowName == ""} {
# Dialog canceled
# abort operation return
}
## Debug puts "Window name: $windowName\n" if {$windowName == "{}"} { set windowName ""
} if {$windowName != ""} { named_wave $windowName
} else { named_wave $defaultName
}
}
## Creates a new wave window with the provided name (defaults to "Wave") proc named_wave {{name "Wave"}} { set newWave [view -new wave] if {[string length $name] > 0} { wm title $newWave $name
}
}
## Writes out format of all wave windows, stores geometry and title info in
## windowSet.do file. Removes any extra files with the same fileroot.
## Default file name is wave<n> starting from 1.
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proc save_wave {{fileroot "wave"}} { global vsimPriv set n 1 if {[catch {open windowSet_$fileroot.do w 755} fileId]} { error "Open failure for $fileroot ($fileId)"
} foreach w $vsimPriv(WaveWindows) { echo "Saving: [wm title $w]" set filename $fileroot$n.do
if {[file exists $filename]} {
# Use different file set n2 0 while {[file exists ${fileroot}${n}${n2}.do]} { incr n2
} set filename ${fileroot}${n}${n2}.do
} write format wave -window $w $filename puts $fileId "wm title $w \"[wm title $w]\"" puts $fileId "wm geometry $w [wm geometry $w]" puts $fileId "mtiGrid_colconfig $w.grid name -width \
[mtiGrid_colcget $w.grid name -width]" puts $fileId "mtiGrid_colconfig $w.grid value -width \
[mtiGrid_colcget $w.grid value -width]" flush $fileId incr n
} foreach f [lsort [glob -nocomplain $fileroot\[$n-9\].do]] { echo "Removing: $f" exec rm $f
}
}
}
## Provide file root argument and load_wave restores all saved windows.
## Default file root is "wave".
proc load_wave {{fileroot "wave"}} { foreach f [lsort [glob -nocomplain $fileroot\[1-9\].do]] { echo "Loading: $f" view -new wave do $f
} if {[file exists windowSet_$fileroot.do]} { do windowSet_$fileroot.do
}
}
...
This next example specifies the compiler arguments and lets you compile any number of files.
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Macros (DO Files)
set Files [list] set nbrArgs $argc for {set x 1} {$x <= $nbrArgs} {incr x} { set lappend Files $1 shift
} eval vcom -93 -explicit -noaccel $Files
This example is an enhanced version of the last one. The additional code determines whether the files are VHDL or Verilog and uses the appropriate compiler and arguments depending on the file type. Note that the macro assumes your VHDL files have a .vhd file extension.
set vhdFiles [list] set vFiles [list] set nbrArgs $argc for {set x 1} {$x <= $nbrArgs} {incr x} { if {[string match *.vhd $1]} { lappend vhdFiles $1
} else { lappend vFiles $1
} shift
} if {[llength $vhdFiles] > 0} { eval vcom -93 -explicit -noaccel $vhdFiles
} if {[llength $vFiles] > 0} { eval vlog $vFiles
}
Macros (DO Files)
ModelSim macros (also called DO files) are simply scripts that contain ModelSim and, optionally, Tcl commands. You invoke these scripts with the Tools > TCL > Execute Macro menu selection or the do command.
Creating DO Files
You can create DO files, like any other Tcl script, by typing the required commands in any editor and saving the file. Alternatively, you can save the transcript as a DO file (see
All "event watching" commands (e.g.
onbreak , onerror , etc.) must be placed before run commands within the macros in order to take effect.
The following is a simple DO file that was saved from the transcript. It is used in the dataset exercise in the ModelSim Tutorial. This DO file adds several signals to the Wave window, provides stimulus to those signals, and then advances the simulation.
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Macros (DO Files)
add wave ld add wave rst add wave clk add wave d add wave q force -freeze clk 0 0, 1 {50 ns} -r 100 force rst 1 force rst 0 10 force ld 0 force d 1010 onerror {cont} run 1700 force ld 1 run 100 force ld 0 run 400 force rst 1 run 200 force rst 0 10 run 1500
Using Parameters with DO Files
You can increase the flexibility of DO files by using parameters. Parameters specify values that are passed to the corresponding parameters $1 through $9 in the macro file. For example say the macro "testfile" contains the line bp $1 $2. The command below would place a breakpoint in the source file named design.vhd at line 127:
do testfile design.vhd
127
There is no limit on the number of parameters that can be passed to macros, but only nine values are visible at one time. You can use the shift command to see the other parameters.
Deleting a File from a .do Script
To delete a file from a .do script, use the Tcl file command as follows:
file delete myfile.log
This will delete the file "myfile.log."
You can also use the transcript file command to perform a deletion:
transcript file () transcript file my file.log
The first line will close the current log file. The second will open a new log file. If it has the same name as an existing file, it will replace the previous one.
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Making Macro Parameters Optional
If you want to make macro parameters optional (i.e., be able to specify fewer parameter values with the do command than the number of parameters referenced in the macro), you must use the
simulator state variable. The argc simulator state variable returns the number of
parameters passed. The examples below show several ways of using argc.
Example 1
This macro specifies the files to compile and handles 0-2 compiler arguments as parameters. If you supply more arguments, ModelSim generates a message.
switch $argc {
0 {vcom file1.vhd file2.vhd file3.vhd }
1 {vcom $1 file1.vhd file2.vhd file3.vhd }
2 {vcom $1 $2 file1.vhd file2.vhd file3.vhd } default {echo Too many arguments. The macro accepts 0-2 args. }
}
Example 2
This macro specifies the compiler arguments and lets you compile any number of files.
variable Files "" set nbrArgs $argc for {set x 1} {$x <= $nbrArgs} {incr x} { set Files [concat $Files $1] shift
} eval vcom -93 -explicit -noaccel $Files
Example 3
This macro is an enhanced version of the one shown in example 2. The additional code determines whether the files are VHDL or Verilog and uses the appropriate compiler and arguments depending on the file type. Note that the macro assumes your VHDL files have a
.vhd file extension.
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Macros (DO Files)
variable vhdFiles "" variable vFiles "" set nbrArgs $argc set vhdFilesExist 0 set vFilesExist 0 for {set x 1} {$x <= $nbrArgs} {incr x} { if {[string match *.vhd $1]} { set vhdFiles [concat $vhdFiles $1] set vhdFilesExist 1
} else { set vFiles [concat $vFiles $1] set vFilesExist 1
} shift
} if {$vhdFilesExist == 1} { eval vcom -93 -explicit -noaccel $vhdFiles
} if {$vFilesExist == 1} { eval vlog $vFiles
}
Useful Commands for Handling Breakpoints and Errors
If you are executing a macro when your simulation hits a breakpoint or causes a run-time error,
ModelSim interrupts the macro and returns control to the command line. The following commands may be useful for handling such events. (Any other legal command may be executed as well.)
Table 13-8. Commands for Handling Breakpoints and Errors in Macros command result
run
-continue
onbreak continue as if the breakpoint had not been executed, completes the run that was interrupted specify a command to run when you hit a breakpoint within a macro onElabError onerror status abort pause specify a command to run when an error is encountered during elaboration specify a command to run when an error is encountered within a macro get a traceback of nested macro calls when a macro is interrupted terminate a macro once the macro has been interrupted or paused cause the macro to be interrupted; the macro can be resumed by entering a resume command via the command line
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Macros (DO Files)
You can also set the OnErrorDefaultAction Tcl variable to determine what action ModelSim takes when an error occurs. To set the variable on a permanent basis, you must define the variable in a modelsim.tcl file (see
for details).
Error Action in DO Files
If a command in a macro returns an error, ModelSim does the following:
1. If an onerror command has been set in the macro script, ModelSim executes that command. The onerror command must be placed prior to the run command in the DO file to take effect.
2. If no onerror command has been specified in the script, ModelSim checks the
OnErrorDefaultAction variable. If the variable is defined, its action will be invoked.
3. If neither 1 or 2 is true, the macro aborts.
Using the Tcl Source Command with DO Files
Either the do command or Tcl source command can execute a DO file, but they behave differently.
With the source command, the DO file is executed exactly as if the commands in it were typed in by hand at the prompt. Each time a breakpoint is hit, the Source window is updated to show the breakpoint. This behavior could be inconvenient with a large DO file containing many breakpoints.
When a do command is interrupted by an error or breakpoint, it does not update any windows, and keeps the DO file "locked". This keeps the Source window from flashing, scrolling, and moving the arrow when a complex DO file is executed. Typically an onbreak resume command is used to keep the macro running as it hits breakpoints. Add an onbreak abort command to the DO file if you want to exit the macro and update the Source window.
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Appendix A
Simulator Variables
This appendix documents the following types of variables:
•
Environment Variables — Variables referenced and set according to operating system
conventions. Environment variables prepare the ModelSim environment prior to simulation.
•
Simulator Control Variables — Variables used to control compiler, simulator, and
various other functions.
•
— Variables that provide feedback on the state of the current simulation.
Variable Settings Report
The report command returns a list of current settings for either the simulator state or simulator control variables. Use the following commands at either the ModelSim or VSIM prompt:
report simulator state report simulator control
Environment Variables
Environment Variable Expansion
The shell commands vcom , vlog , vsim , and vmap , no longer expand environment variables in filename arguments and options. Instead, variables should be expanded by the shell beforehand, in the usual manner. The -f option that most of these commands support, now performs environment variable expansion throughout the file.
Environment variable expansion is still performed in the following places:
•
Pathname and other values in the modelsim.ini file
•
Strings used as file pathnames in VHDL and Verilog
•
VHDL Foreign attributes
•
The
PLIOBJS environment variable may contain a path that has an environment
variable.
•
Verilog `uselib file and dir directives
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•
Anywhere in the contents of a -f file
The recommended method for using flexible pathnames is to make use of the MGC Location
Map system (see
Using Location Mapping ). When this is used, then pathnames stored in
libraries and project files (.mpf) will be converted to logical pathnames.
If a file or path name contains the dollar sign character ($), and must be used in one of the places listed above that accepts environment variables, then the explicit dollar sign must be escaped by using a double dollar sign ($$).
Setting Environment Variables
Before compiling or simulating, several environment variables may be set to provide the functions described below. The variables are set through the System control panel on Windows
2000 and XP machines. For UNIX, the variables are typically found in the .login script. The
LM_LICENSE_FILE variable is required; all others are optional.
DOPATH
The toolset uses the DOPATH environment variable to search for DO files (macros). DOPATH consists of a colon-separated (semi-colon for Windows) list of paths to directories. You can override this environment variable with the DOPATH Tcl preference variable.
The DOPATH environment variable isn’t accessible when you invoke vsim from a UNIX shell or from a Windows command prompt. It is accessible once ModelSim or vsim is invoked. If you need to invoke from a shell or command line and use the DOPATH environment variable, use the following syntax: vsim -do "do <dofile_name>" <design_unit>
EDITOR
The EDITOR environment variable specifies the editor to invoke with the edit command
HOME
The toolset uses the HOME environment variable to look for an optional graphical preference file and optional location map file. Refer to
Simulator Control Variables for additional
information.
HOME_0IN
The HOME_0IN environment variable identifies the location of the 0-In executables directory.
Refer to the 0-In documentation for more information.
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LD_LIBRARY_PATH
A UNIX shell environment variable setting the search directories for shared libraries. It instructs the OS where to search for the shared libraries for FLI/PLI/VPI/DPI. This variable is used for both 32-bit and 64-bit shared libraries on Solaris/Linux systems.
LD_LIBRARY_PATH_32
A UNIX shell environment variable setting the search directories for shared libraries. It instructs the OS where to search for the shared libraries for FLI/PLI/VPI/DPI. This variable is used only for 32-bit shared libraries on Solaris/Linux systems.
LD_LIBRARY_PATH_64
A UNIX shell environment variable setting the search directories for shared libraries. It instructs the OS where to search for the shared libraries for FLI/PLI/VPI/DPI. This variable is used only for 64-bit shared libraries on Solaris/Linux systems.
LM_LICENSE_FILE
The toolset’s file manager uses the LM_LICENSE_FILE environment variable to find the location of the license file. The argument may be a colon-separated (semi-colon for Windows) set of paths, including paths to other vendor license files. The environment variable is required.
MODEL_TECH
The toolset automatically sets the MODEL_TECH environment variable to the directory in which the binary executable resides; DO NOT SET THIS VARIABLE!
MODEL_TECH_TCL
The toolset uses the MODEL_TECH_TCL environment variable to find Tcl libraries for Tcl/Tk
8.3 and vsim, and may also be used to specify a startup DO file. This variable defaults to
/modeltech/../tcl, however you may set it to an alternate path
MGC_LOCATION_MAP
The toolset uses the MGC_LOCATION_MAP environment variable to find source files based on easily reallocated "soft" paths.
MODELSIM
The toolset uses the MODELSIM environment variable to find the modelsim.ini file. The argument consists of a path including the file name.
An alternative use of this variable is to set it to the path of a project file
(<Project_Root_Dir>/<Project_Name>.mpf). This allows you to use project settings with
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command line tools. However, if you do this, the .mpf file will replace modelsim.ini as the initialization file for all tools.
MODELSIM_PREFERENCES
The MODELSIM_PREFERENCES environment variable specifies the location to store user interface preferences. Setting this variable with the path of a file instructs the toolset to use this file instead of the default location (your HOME directory in UNIX or in the registry in
Windows). The file does not need to exist beforehand, the toolset will initialize it. Also, if this file is read-only, the toolset will not update or otherwise modify the file. This variable may contain a relative pathname – in which case the file will be relative to the working directory at the time the tool is started.
MODELSIM_TCL
The toolset uses the MODELSIM_TCL environment variable to look for an optional graphical preference file. The argument can be a colon-separated (UNIX) or semi-colon separated
(Windows) list of file paths.
MTI_COSIM_TRACE
The MTI_COSIM_TRACE environment variable creates an mti_trace_cosim file containing debugging information about FLI/PLI/VPI function calls. You should set this variable to any value before invoking the simulator.
MTI_TF_LIMIT
The MTI_TF_LIMIT environment variable limits the size of the VSOUT temp file (generated by the toolset’s kernel). Set the argument of this variable to the size of k-bytes
The environment variable TMPDIR controls the location of this file, while STDOUT controls the name. The default setting is 10, and a value of 0 specifies that there is no limit. This variable does not control the size of the transcript file.
MTI_RELEASE_ON_SUSPEND
The MTI_RELEASE_ON_SUSPEND environment variable allows you to turn off or modify the delay for the functionality of releasing all licenses when the tool is suspended. The default setting is 10 (in seconds), which means that if you do not set this variable your licenses will be released 10 seconds after your run is suspended. If you set this environment variable with an argument of 0 (zero) the tool will not release the licenses after being suspended. You can change the default length of time (number of seconds) by setting this environment variable to an integer greater than 0 (zero).
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MTI_USELIB_DIR
The MTI_USELIB_DIR environment variable specifies the directory into which object libraries are compiled when using the -compile_uselibs argument to the vlog command
NOMMAP
When set to 1, the NOMMAP environment variable disables memory mapping in the toolset.
You should only use this variable when running on Linux 7.1 because it will decrease the speed with which the tool reads files.
PLIOBJS
The toolset uses the PLIOBJS environment variable to search for PLI object files for loading.
The argument consists of a space-separated list of file or path names
STDOUT
The argument to the STDOUT environment variable specifies a filename to which the simulator saves the VSOUT temp file information. Typically this information is deleted when the simulator exits. The location for this file is set with the TMPDIR variable, which allows you to find and delete the file in the event of a crash, because an unnamed VSOUT file is not deleted after a crash.
TMP
(Windows environments) The TMP environment variable specifies the path to a tempnam() generated file (VSOUT) containing all stdout from the simulation kernel.
TMPDIR
(UNIX environments) The TMPDIR environment variable specifies the path to a tempnam() generated file (VSOUT) containing all stdout from the simulation kernel.
Creating Environment Variables in Windows
In addition to the predefined variables shown above, you can define your own environment variables. This example shows a user-defined library path variable that can be referenced by the
vmap command to add library mapping to the modelsim.ini file.
1. From your desktop, right-click your My Computer icon and select Properties
2. In the System Properties dialog box, select the Advanced tab
3. Click Environment Variables
4. In the Environment Variables dialog box and User variables for <user> pane, select
New:
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5. In the New User Variable dialog box, add the new variable with this data
Variable ame: MY_PATH
Variable value:\temp\work
6. OK (New User Variable, Environment Variable, and System Properties dialog boxes)
Library Mapping with Environment Variables
Once the MY_PATH variable is set, you can use it with the vmap command to add library mappings to the current modelsim.ini file.
Table A-1. Add Library Mappings to modelsim.ini File
Prompt Type Command Result added to modelsim.ini
DOS prompt vmap MY_VITAL %MY_PATH% MY_VITAL = c:\temp\work
ModelSim or vsim prompt vmap MY_VITAL \$MY_PATH
1
MY_VITAL = $MY_PATH
1. The dollar sign ($) character is Tcl syntax that indicates a variable. The backslash (\) character is an escape character that prevents the variable from being evaluated during the execution of vmap.
You can easily add additional hierarchy to the path. For example,
vmap MORE_VITAL %MY_PATH%\more_path\and_more_path vmap MORE_VITAL \$MY_PATH\more_path\and_more_path
Referencing Environment Variables
There are two ways to reference environment variables within ModelSim. Environment variables are allowed in a FILE variable being opened in VHDL. For example, use std.textio.all; entity test is end; architecture only of test is begin process
FILE in_file : text is in "$ENV_VAR_NAME"; begin wait; end process; end;
Environment variables may also be referenced from the ModelSim command line or in macros using the Tcl env array mechanism:
echo "$env(ENV_VAR_NAME)"
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Note
Environment variable expansion does not occur in files that are referenced via the -f argument to vcom, vlog, or vsim.
Removing Temp Files (VSOUT)
The VSOUT temp file is the communication mechanism between the simulator kernel and the
Graphical User Interface. In normal circumstances the file is deleted when the simulator exits. If the tool crashes, however, the temp file must be deleted manually. Specifying the location of the temp file with TMPDIR (above) will help you locate and remove the file.
Simulator Control Variables
Initialization (INI) files contain control variables that specify reference library paths and compiler and simulator settings. The default initialization file is modelsim.ini and is located in your install directory.
To set these variables, edit the initialization file directly with any text editor. The syntax for variables in the file is:
<variable> = <value>
Comments within the file are preceded with a semicolon ( ; ).
The following sections contain information about the variables:
•
•
Verilog Compiler Control Variables
•
VHDL Compiler Control Variables
•
Library Path Variables
You can find these variables under the heading [Library] in the modelsim.ini file.
ieee
This variable sets the path to the library containing IEEE and Synopsys arithmetic packages.
•
Value Range: any valid path; may include environment variables
•
Default: $MODEL_TECH/../ieee
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modelsim_lib
This variable sets the path to the library containing Model Technology VHDL utilities such as
Signal Spy.
•
Value Range: any valid path; may include environment variables
•
Default: $MODEL_TECH/../modelsim_lib
std
This variable sets the path to the VHDL STD library.
•
Value Range: any valid path; may include environment variables
•
Default: $MODEL_TECH/../std
std_developerskit
This variable sets the path to the libraries for MGC standard developer’s kit.
•
Value Range: any valid path; may include environment variables
•
Default: $MODEL_TECH/../std_developerskit
synopsys
This variable sets the path to the accelerated arithmetic packages.
•
Value Range: any valid path; may include environment variables
•
Default: $MODEL_TECH/../synopsys
sv_std
This variable sets the path to the SystemVerilog STD library.
•
Value Range: any valid path; may include environment variables
•
Default: $MODEL_TECH/../sv_std
verilog
This variable sets the path to the library containing VHDL/Verilog type mappings.
•
Value Range: any valid path; may include environment variables
•
Default: $MODEL_TECH/../verilog
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vital2000
This variable sets the path to the VITAL 2000 library
•
Value Range: any valid path; may include environment variables
•
Default: $MODEL_TECH/../vital2000
others
This variable points to another modelsim.ini file whose library path variables will also be read; the pathname must include "modelsim.ini"; only one others variable can be specified in any
modelsim.ini file.
•
Value Range: any valid path; may include environment variables
•
Default: none
Verilog Compiler Control Variables
You can find these variables under the heading [vlog] in the modelsim.ini file.
DisableOpt
This variable, when on, disables all optimizations enacted by the compiler; same as the -O0 argument to vlog.
•
Value Range: 0, 1
•
Default: off (0)
GenerateLoopIterationMax
This variable specifies the maximum number of iterations permitted for a generate loop; restricting this permits the implementation to recognize infinite generate loops.
•
Value Range: natural integer (>=0)
•
Default: 100000
GenerateRecursionDepthMax
This variable specifies the maximum depth permitted for a recursive generate instantiation; restricting this permits the implementation to recognize infinite recursions.
•
Value Range: natural integer (>=0)
•
Default: 200
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Hazard
This variable turns on Verilog hazard checking (order-dependent accessing of global variables).
•
Value Range: 0, 1
•
Default: off (0)
Incremental
This variable activates the incremental compilation of modules.
•
Value Range: 0, 1
•
Default: off (0)
MultiFileCompilationUnit
Controls how Verilog files are compiled into compilation units. Valid arguments:
•
1 -- (0n) Compiles all files on command line into a single compilation unit. This behavior is called Multi File Compilation Unit (MFCU) mode; same as -mfcu argument to
•
0 -- (Off) Default value. Compiles each file in the compilation command line into separate compilation units. This behavior is called Single File Compilation Unit (SFCU) mode.
Refer to
SystemVerilog Multi-File Compilation Issues for details on the implications of these
settings.
Note
The default behavior in versions prior to 6.1 was opposite of the current default behavior.
NoDebug
This variable, when on, disables the inclusion of debugging info within design units.
•
Value Range: 0, 1
•
Default: off (0)
Quiet
This variable turns off "loading…" messages.
•
Value Range: 0, 1
•
Default: off (0)
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Show_BadOptionWarning
This variable instructs the tool to generate a warning whenever an unknown plus argument is encountered.
•
Value Range: 0, 1
•
Default: off (0)
Show_Lint
This variable instructs the tool to display lint warning messages.
•
Value Range: 0, 1
•
Default: off (0)
Show_WarnCantDoCoverage
This variable instructs the tool to display warning messages when the simulator encounters constructs which code coverage cannot handle.
•
Value Range: 0,1
•
Default: on (1)
Show_WarnMatchCadence
This variable instructs the tool to display warning messages about non-LRM compliance in order to match Cadence behavior.
•
Value Range: 0, 1
•
Default: on (1)
Show_source
This variable instructs the tool to show any source line containing an error.
•
Value Range: 0, 1
•
Default: off (0)
vlog95compat
This variable instructs the tool to disable SystemVerilog and Verilog 2001 support, making the compiler compatible with IEEE Std 1364-1995.
•
Value Range: 0, 1
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•
Default: off (0)
VHDL Compiler Control Variables
You can find these variables under the heading [vcom].
BindAtCompile
This variable instructs the tool to perform VHDL default binding at compile time rather than load time. Refer to
Default Binding for more information.
•
Value Range: 0, 1
•
Default: off (0)
CheckSynthesis
This variable turns on limited synthesis rule compliance checking, which includes checking only signals used (read) by a process and understanding only combinational logic, not clocked logic.
•
Value Range: 0, 1
•
Default: off (0)
DisableOpt
This variable disables all optimizations enacted by the compiler, similar to using the -O0 argument to vcom.
•
Value Range: 0, 1
•
Default: off (0)
Explicit
This variable enables the resolving of ambiguous function overloading in favor of the "explicit" function declaration (not the one automatically created by the compiler for each type declaration).
•
Value Range: 0, 1
•
Default: on (1)
IgnoreVitalErrors
This variable instructs the tool to ignore VITAL compliance checking errors.
•
Value Range: 0, 1
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•
Default: off (0)
NoCaseStaticError
This variable changes case statement static errors to warnings.
•
Value Range: 0, 1
•
Default: off (0)
NoDebug
This variable disables turns off inclusion of debugging info within design units.
•
Value Range: 0, 1
•
Default: off (0)
NoIndexCheck
This variable disables run time index checks.
•
Value Range: 0, 1
•
Default: off (0)
NoOthersStaticError
This variable disables errors caused by aggregates that are not locally static.
•
Value Range: 0, 1
•
Default: off (0)
NoRangeCheck
This variable disables run time range checking.
•
Value Range: 0, 1
•
Default: off (0)
NoVital
This variable disables acceleration of the VITAL packages.
•
Value Range: 0, 1
•
Default: off (0)
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NoVitalCheck
This variable disables VITAL compliance checking.
•
Value Range: 0, 1
•
Default: off (0)
Optimize_1164
This variable disables optimization for the IEEE std_logic_1164 package.
•
Value Range: 0, 1
•
Default: on (1)
PedanticErrors
This variable overrides NoCaseStaticError and NoOthersStaticError
•
Value Range: 0, 1
•
Default: off(0)
Quiet
This variable disables the “loading…” messages.
•
Value Range: 0, 1
•
Default: off (0)
RequireConfigForAllDefaultBinding
This variable instructs the compiler not to generate a default binding during compilation.
•
Value Range: 0, 1
•
Default: off (0)
Show_Lint
This variable enables lint-style checking.
•
Value Range: 0, 1
•
Default: off (0)
Show_source
This variable shows source line containing error.
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•
Value Range: 0, 1
•
Default: off (0)
Show_VitalChecksOpt
This variable enables VITAL optimization warnings.
•
Value Range: 0, 1
•
Default: on (1)
Show_VitalChecksWarnings
This variable enables VITAL compliance-check warnings.
•
Value Range: 0, 1
•
Default: on (1)
Show_WarnCantDoCoverage
This variable enables warnings when the simulator encounters constructs which code coverage cannot handle.
•
Value Range: 0, 1
•
Default: on (1)
Show_Warning1
This variable enables unbound-component warnings.
•
Value Range: 0, 1
•
Default: on (1)
Show_Warning2
This variable enables process-without-a-wait-statement warnings.
•
Value Range: 0, 1
•
Default: on (1)
Show_Warning3
This variable enables null-range warnings.
•
Value Range: 0, 1
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•
Default: on (1)
Show_Warning4
This variable enables no-space-in-time-literal warnings.
•
Value Range: 0, 1
•
Default: on (1)
Show_Warning5
This variable enables multiple-drivers-on-unresolved-signal warnings.
•
Value Range: 0, 1
•
Default: on (1)
Show_Warning9
This variable enables warnings about signal value dependency at elaboration.
•
Value Range: 0, 1
•
Default: on (1)
Show_Warning10
This variable enables warnings about VHDL-1993 constructs in VHDL-1987 code.
•
Value Range: 0, 1
•
Default: on (1)
Show_WarnLocallyStaticError
This variable enables warnings about locally static errors deferred until run time.
•
Value Range: 0, 1
•
Default: on (1)
VHDL93
This variable enables support for VHDL-1987, where “1” enables support for VHDL-1993 and
“2” enables support for VHDL-2002.
•
Value Range: 0, 1, 2
•
Default: 2
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Simulation Control Variables
You can find these variables under the heading [vsim] in the modelsim.ini file.
AssertFile
This variable specifies an alternative file for storing VHDL assertion messages.
•
Value Range: any valid filename
•
Default: transcript
AssertionDebug
This variable specifies that SVA assertion passes are reported.
•
Value Range: 0, 1
•
Default: off (0)
AssertionFormat
This variable defines the format of VHDL assertion messages.
•
Value Range:
%T
%D
%I
%i
Table A-2. AssertionFormat Variable: Accepted Values
Variable Description
%S
%R severity level report message
%O
%K time of assertion delta instance or region pathname (if available) instance pathname with process process name kind of object path points to; returns Instance, Signal,
Process, or Unknown
%P
%F
%L
%% instance or region path without leaf process file line number of assertion, or if from subprogram, line from which call is made print ’%’ character
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•
Default: "** %S: %R\n Time: %T Iteration: %D%I\n"
AssertionFormatBreak
This variable defines the format of messages for VHDL assertions that trigger a breakpoint.
•
Value Range: Refer to
•
Default: "** %S: %R\n Time: %T Iteration: %D %K: %i File: %F\n"
AssertionFormatError
This variable defines the format of messages for VHDL Error assertions.
If undefined, AssertionFormat is used unless assertion causes a breakpoint in which case
AssertionFormatBreak is used.
•
Value Range: Refer to
•
Default: "** %S: %R\n Time: %T Iteration: %D %K: %i File: %F\n"
AssertionFormatFail
This variable defines the format of messages for VHDL Fail assertions.
If undefined, AssertionFormat is used unless assertion causes a breakpoint in which case
AssertionFormatBreak is used
•
Value Range: Refer to
•
Default: "** %S: %R\n Time: %T Iteration: %D %K: %i File: %F\n"
AssertionFormatFatal
This variable defines the format of messages for VHDL Fatal assertions
If undefined, AssertionFormat is used unless assertion causes a breakpoint in which case
AssertionFormatBreak is used.
•
Value Range: Refer to
•
Default: "** %S: %R\n Time: %T Iteration: %D %K: %i File: %F\n"
AssertionFormatNote
This variable defines the format of messages for VHDL Note assertions
If undefined, AssertionFormat is used unless assertion causes a breakpoint in which case
AssertionFormatBreak is used
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•
Value Range: Refer to
•
Default: "** %S: %R\n Time: %T Iteration: %D%I\n"
AssertionFormatWarning
This variable defines the format of messages for VHDL Warning assertions
If undefined, AssertionFormat is used unless assertion causes a breakpoint in which case
AssertionFormatBreak is used
•
Value Range: Refer to
•
Default: "** %S: %R\n Time: %T Iteration: %D%I\n"
BreakOnAssertion
This variable defines the severity of VHDL assertions that cause a simulation break. It also controls any messages in the source code that use assertion_failure_*. For example, since most runtime messages use some form of assertion_failure_*, any runtime error will cause the simulation to break if the user sets BreakOnAssertion to 2.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: 0 (note), 1 (warning), 2 (error), 3 (failure), 4 (fatal)
•
Default: 3 (failure)
CheckPlusargs
This variable defines the simulator’s behavior when encountering unrecognized plusargs.
•
Value Range: 0 (ignores), 1 (issues warning, simulates while ignoring), 2 (issues error, exits)
•
Default: 0 (ignores)
CheckpointCompressMode
This variable specifies that checkpoint files are written in compressed format
•
Value Range: 0, 1
•
Default: on (1)
CommandHistory
This variable specifies the name of a file in which to store the Main window command history.
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•
Value Range: any valid filename
•
Default: commented out (;)
ConcurrentFileLimit
This variable controls the number of VHDL files open concurrently. This number should be less than the current limit setting for max file descriptors.
•
Value Range: any positive integer or 0 (unlimited)
•
Default: 40
DatasetSeparator
This variable specifies the dataset separator for fully-rooted contexts, for example: sim:/top
The argument to DatasetSeparator must not be the same character as PathSeparator
•
Value Range: any character except those with special meaning, such as \, {, }, etc.
•
Default: :
DefaultForceKind
This variable defines the kind of force used when not otherwise specified.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: freeze, drive, or deposit
•
Default: drive, for resolved signals; freeze, for unresolved signals
DefaultRadix
This variable specifies a numeric radix may be specified as a name or number. For example, you can specify binary as “binary” or “2” or octal as “octal” or “8”.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: symbolic, binary, octal, decimal, unsigned, hexadecimal, ascii
•
Default: symbolic
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DefaultRestartOptions
This variable sets the default behavior for the restart command
•
Value Range: one or more of: -force, -noassertions, -nobreakpoint, -nofcovers, -nolist,
-nolog, -nowave
•
Default: commented out (;)
DelayFileOpen
This variable instructs the tool to open VHDL87 files on first read or write, else open files when elaborated.
•
Value Range: 0, 1
•
Default: off (0)
DumpportsCollapse
This variable collapses vectors (VCD id entries) in dumpports output.
•
Value Range: 0, 1
•
Default: off (0)
GenerateFormat
This variable controls the format of a generate statement label. Do not enclose the argument in quotation marks.
•
Value Range: Any non-quoted string containing at a minimum a %s followed by a %d
•
Default: %s__%d
GlobalSharedObjectsList
This variable instruct the tool to load the specified PLI/FLI shared objects with global symbol visibility.
•
Value Range: comma separated list of filenames
•
Default: commented out (;)
IgnoreError
This variable instructs the tool to ignore VHDL assertion errors.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
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•
Value Range: 0,1
•
Default: off (0)
IgnoreFailure
This variable instructs the tool to ignore VHDL assertion failures.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: 0,1
•
Default: off (0)
IgnoreNote
This variable instructs the tool to ignore VHDL assertion notes.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: 0,1
•
Default: off (0)
IgnoreWarning
This variable instructs the tool to ignore VHDL assertion warnings.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: 0,1
•
Default: off (0)
IterationLimit
This variable specifies a limit on simulation kernel iterations allowed without advancing time.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: positive integer
•
Default: 5000
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License
This variable controls the license file search.
•
Value Range: one ore more of the following <license_option>, separated by spaces if using multiple entries. Refer also to the vsim <license_option>.
Table A-3. License Variable: License Options license_option Description
lnlonly mixedonly only use msimhdlsim and hdlsim exclude single language licenses nomgc nolnl nomix nomti exclude MGC licenses exclude language neutral licenses exclude msimhdlmix and hdlmix exclude MTI licenses noqueue noslvhdl noslvlog plus vlog vhdl do not wait in license queue if no licenses are available exclude qhsimvh and vsim exclude qhsimvl and vsimvlog only use PLUS license only use VLOG license only use VHDL license
•
Default: search all licenses
LockedMemory
For HP-UX 10.2 use only. This variable enables memory locking to speed up large designs (>
500mb memory footprint)
•
Value Range: positive integer in units of MB.
•
Default: disabled
MaxReportRhsCrossProducts
This variable specifies a limit on number of Cross (bin) products which are listed against a
Cross when a XML or UCDB report is generated. The warning reports when any instance of unusually high number of Cross (bin) product and truncation of Cross (bin) product list for a
Cross.
•
Value Range: positive integer
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•
Default: 1000
NumericStdNoWarnings
This variable disables warnings generated within the accelerated numeric_std and numeric_bit packages.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: 0, 1
•
Default: off (0)
OnFinish
This variable controls the behavior of the tool when it encounters $finish in the design code.
•
Value Range:
•
ask — o
In batch mode, the simulation exits.
o
In GUI mode, a dialog box pops up and asks for user confirmation on whether to quit the simulation.
•
stop — Causes the simulation to stay loaded in memory. This can make some postsimulation tasks easier.
•
exit — The simulation exits without asking for any confirmation.
•
Default: ask — Exits in batch mode; prompts user in GUI mode.
PathSeparator
This variable specifies the character used for hierarchical boundaries of HDL modules. This variable does not affect file system paths. The argument to PathSeparator must not be the same character as DatasetSeparator.
•
Value Range: any character except those with special meaning, such as \, {, }, etc.
•
Default: /
PrintSimStats
This variable instructs the simulator to print the output of the simstats command upon exit. You can set this variable interactively with the -printsimstats argument to the vsim command.
•
Value Range: 0, 1
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•
Default: 0
Resolution
This variable specifies the simulator resolution. The argument must be less than or equal to the
and must not contain a space between value and units, for example:
Resoultion = 10fs
You can override this value with the -t argument to vsim . You should set a smaller resolution if your delays get truncated.
•
Value Range: fs, ps, ns, us, ms, or sec with optional prefix of 1, 10, or 100
•
Default: ps
RunLength
This variable specifies the default simulation length in units specified by the
variable
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: positive integer
•
Default: 100
ShowFunctions
This variable sets the format for Breakpoint and Fatal error messages. When set to 1 (the default value), messages will display the name of the function, task, subprogram, module, or architecture where the condition occurred, in addition to the file and line number. Set to 0 to revert messages to previous format.
•
Value Range: 0, 1
•
Default: 1
SignalSpyPathSeparator
This variable specifies a unique path separator for the Signal Spy functions. The argument to
SignalSpyPathSeparator must not be the same character as DatasetSeparator.
•
Value Range: any character except those with special meaning, such as \, {, }, etc.
•
Default: /
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Startup
This variable specifies a simulation startup macro. Refer to the do command
•
Value Range: = do <DO filename>; any valid macro (do) file
•
Default: commented out (;)
StdArithNoWarnings
This variable suppresses warnings generated within the accelerated Synopsys std_arith packages.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: 0, 1
•
Default: off (0)
ToggleMaxIntValues
This variable sets the maximum number of VHDL integer values to record with toggle coverage.
•
Value Range: positive integer
•
Default: 100
TranscriptFile
This variable specifies a file for saving command transcript. You can specify environment variables in the pathname.
•
Value Range: any valid filename
•
Default: transcript
UnbufferedOutput
This variable controls VHDL and Verilog files open for write.
•
Value Range: 0 (buffered), 1 (unbuffered)
•
Default: 0
UseCsupV2
Applies only to HP-UX 11.00 and when you compiled FLI/PLI/VPI C++ code with the -AA option for aCC.
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This variable instructs vsim to use /usr/lib/libCsup_v2.sl for shared object loading.
•
Value Range: 0, 1
•
Default: off (0)
UserTimeUnit
This variable specifies scaling for the Wave window and the default time units to use for commands such as force and run . You should generally set this variable to default, in which case it takes the value of the Resolution variable.
•
Value Range: fs, ps, ns, us, ms, sec, or default
•
Default: default
Veriuser
This variable specifies a list of dynamically loadable objects for Verilog PLI/VPI applications.
•
Value Range: one or more valid shared object names
•
Default: commented out (;)
WarnConstantChange
This variable controls whether a warning is issued when the change command changes the value of a VHDL constant or generic.
•
Value Range: 0, 1
•
Default: on (1)
WaveSignalNameWidth
This variable controls the number of visible hierarchical regions of a signal name shown in the
•
Value Range: 0 (display full name), positive integer (display corresponding level of hierarchy)
•
Default: 0
WLFCacheSize
This variable sets the number of megabytes for the WLF reader cache; WLF reader caching caches blocks of the WLF file to reduce redundant file I/O
•
Value Range: positive integer
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•
Default: 0
WLFCollapseMode
This variable controls when the WLF file records values.
•
Value Range: 0 (every change of logged object), 1 (end of each delta step), 2 (end of simulator time step)
•
Default: 1
WLFCompress
This variable enables WLF file compression.
•
Value Range: 0, 1
•
Default: 1 (on)
WLFDeleteOnQuit
This variable specifies whether a WLF file should be deleted when the simulation ends.
•
Value Range: 0, 1
•
Default: 0 (do not delete)
WLFFilename
This variable specifies the default WLF file name.
•
Value Range: 0, 1
•
Default: vsim.wlf
WLFOptimize
This variable specifies whether the viewing of waveforms is optimized.
•
Value Range: 0, 1
•
Default: 1 (on)
WLFSaveAllRegions
This variable specifies the regions to save in the WLF file.
•
Value Range: 0 (only regions containing logged signals), 1 (all design hierarchy)
•
Default: 0
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WLFSizeLimit
This variable limits the WLF file by size (as closely as possible) to the specified number of megabytes; if both size and time limits are specified the most restrictive is used.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: any positive integer in units of MB or 0 (unlimited)
•
Default: 0 (unlimited)
WLFTimeLimit
This variable limits the WLF file by time (as closely as possible) to the specified amount of time. If both time and size limits are specified the most restrictive is used.
You can set this variable interactively in the GUI; refer to
Setting Simulator Control Variables
•
Value Range: any positive integer or 0 (unlimited)
•
Default: 0 (unlimited)
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Setting Simulator Control Variables With The GUI
Changes made in the Runtime Options dialog are written to the active modelsim.ini file, if it is writable, and affect the current session as well as all future sessions. If the file is read-only, the changes affect only the current session. The Runtime Options dialog is accessible by selecting
Simulate > Runtime Options in the Main window. The dialog contains three tabs - Defaults,
Assertions, and WLF Files.
The Defaults tab includes these options:
Figure A-1. Runtime Options Dialog: Defaults Tab
342
•
Default Radix — Sets the default radix for the current simulation run. You can also use the radix command to set the same temporary default. The chosen radix is used for all commands ( force , examine , change are examples) and for displayed values in the
Objects, Locals, Dataflow, List, and Wave windows. The corresponding modelsim.ini variable is
.
•
Suppress Warnings
o
Selecting From Synopsys Packages suppresses warnings generated within the accelerated Synopsys std_arith packages. The corresponding modelsim.ini variable is
o
Selecting From IEEE Numeric Std Packages suppresses warnings generated within the accelerated numeric_std and numeric_bit packages. The corresponding
modelsim.ini variable is
•
Default Run — Sets the default run length for the current simulation. The corresponding modelsim.ini variable is
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•
Iteration Limit — Sets a limit on the number of deltas within the same simulation time unit to prevent infinite looping. The corresponding modelsim.ini variable is
.
•
Default Force Type — Selects the default force type for the current simulation. The corresponding modelsim.ini variable is
The Assertions tab includes these options:
Figure A-2. Runtime Options Dialog Box: Assertions Tab
•
No Message Display For -VHDL — Selects the VHDL assertion severity for which messages will not be displayed (even if break on assertion is set for that severity).
Multiple selections are possible. The corresponding modelsim.ini variables are
,
, and
The WLF Files tab includes these options:
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Figure A-3. Runtime Options Dialog Box, WLF Files Tab
•
WLF File Size Limit — Limits the WLF file by size (as closely as possible) to the specified number of megabytes. If both size and time limits are specified, the most restrictive is used. Setting it to 0 results in no limit. The corresponding modelsim.ini variable is
.
•
WLF File Time Limit — Limits the WLF file by size (as closely as possible) to the specified amount of time. If both time and size limits are specified, the most restrictive is used. Setting it to 0 results in no limit. The corresponding modelsim.ini variable is
.
•
WLF Attributes — Specifies whether to compress WLF files and whether to delete the
WLF file when the simulation ends. You would typically only disable compression for troubleshooting purposes. The corresponding modelsim.ini variables are
for compression and
for WLF file deletion.
•
Design Hierarchy — Specifies whether to save all design hierarchy in the WLF file or only regions containing logged signals. The corresponding modelsim.ini variable is
.
Message System Variables
The message system variables (located under the [msg_system] heading) help you identify and troubleshoot problems while using the application. See also
.
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error
This variable changes the severity of the listed message numbers to "error". Refer to
for more information.
•
Value Range: list of message numbers
•
Default: none
fatal
This variable changes the severity of the listed message numbers to "fatal". Refer to
for more information.
•
Value Range: list of message numbers
•
Default: none
note
This variable changes the severity of the listed message numbers to "note". Refer to
for more information
•
Value Range: list of message numbers
•
Default: none
suppress
This variable suppresses the listed message numbers. Refer to
for more information
•
Value Range: list of message numbers
•
Default: none
warning
This variable changes the severity of the listed message numbers to "warning". Refer to
Changing Message Severity Level for more information
•
Value Range: list of message numbers
•
Default: none
msgmode
This variable controls where the simulator outputs elaboration and runtime messages. Refer to the section “
Message Viewer ” for more information.
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•
Value Range: tran (transcript only), wlf (wlf file only), both
•
Default: both
Commonly Used INI Variables
Several of the more commonly used modelsim.ini variables are further explained below.
Common Environment Variables
You can use environment variables in your initialization files. Use a dollar sign ($) before the environment variable name. For example:
[Library] work = $HOME/work_lib test_lib = ./$TESTNUM/work
...
[vsim]
IgnoreNote = $IGNORE_ASSERTS
IgnoreWarning = $IGNORE_ASSERTS
IgnoreError = 0
IgnoreFailure = 0
There is one environment variable, MODEL_TECH, that you cannot — and should not — set.
MODEL_TECH is a special variable set by Model Technology software. Its value is the name of the directory from which the VCOM or VLOG compilers or VSIM simulator was invoked.
MODEL_TECH is used by the other Model Technology tools to find the libraries.
Hierarchical Library Mapping
By adding an "others" clause to your modelsim.ini file, you can have a hierarchy of library mappings. If the ModelSim tools don’t find a mapping in the modelsim.ini file, then they will search only the library section of the initialization file specified by the "others" clause. For example:
[Library] asic_lib = /cae/asic_lib work = my_work others = /install_dir/modeltech/modelsim.ini
Since the file referred to by the "others" clause may itself contain an "others" clause, you can use this feature to chain a set of hierarchical INI files for library mappings.
Creating a Transcript File
A feature in the system initialization file allows you to keep a record of everything that occurs in the transcript: error messages, assertions, commands, command outputs, etc. To do this, set
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the value for the TranscriptFile line in the modelsim.ini file to the name of the file in which you would like to record the ModelSim history.
; Save the command window contents to this file
TranscriptFile = trnscrpt
You can disable the creation of the transcript file by using the following ModelSim command immediately after ModelSim starts: transcript file ""
Using a Startup File
The system initialization file allows you to specify a command or a do file that is to be executed after the design is loaded. For example:
; VSIM Startup command
Startup = do mystartup.do
The line shown above instructs ModelSim to execute the commands in the macro file named
mystartup.do.
; VSIM Startup command
Startup = run -all
The line shown above instructs VSIM to run until there are no events scheduled.
See the do command for additional information on creating do files.
Turning Off Assertion Messages
You can turn off assertion messages from your VHDL code by setting a switch in the
modelsim.ini file. This option was added because some utility packages print a huge number of warnings.
[vsim]
IgnoreNote = 1
IgnoreWarning = 1
IgnoreError = 1
IgnoreFailure = 1
Turning off Warnings from Arithmetic Packages
You can disable warnings from the Synopsys and numeric standard packages by adding the following lines to the [vsim] section of the modelsim.ini file.
[vsim]
NumericStdNoWarnings = 1
StdArithNoWarnings = 1
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Force Command Defaults
The force command has -freeze, -drive, and -deposit options. When none of these is specified, then -freeze is assumed for unresolved signals and -drive is assumed for resolved signals. But if you prefer -freeze as the default for both resolved and unresolved signals, you can change the defaults in the modelsim.ini file.
[vsim]
; Default Force Kind
; The choices are freeze, drive, or deposit
DefaultForceKind = freeze
Restart Command Defaults
The restart command has -force, -nobreakpoint, -nofcovers, -nolist, -nolog, and -nowave options. You can set any of these as defaults by entering the following line in the modelsim.ini file:
DefaultRestartOptions = <options>
where <options> can be one or more of -force, -nobreakpoint, -nofcovers, -nolist, -nolog, and nowave.
Example:
DefaultRestartOptions = -nolog -force
VHDL Standard
You can specify which version of the 1076 Std ModelSim follows by default using the
VHDL93 variable:
[vcom]
; VHDL93 variable selects language version as the default.
; Default is VHDL-2002.
; Value of 0 or 1987 for VHDL-1987.
; Value of 1 or 1993 for VHDL-1993.
; Default or value of 2 or 2002 for VHDL-2002.
VHDL93 = 2002
Opening VHDL Files
You can delay the opening of VHDL files with an entry in the INI file if you wish. Normally
VHDL files are opened when the file declaration is elaborated. If the DelayFileOpen option is enabled, then the file is not opened until the first read or write to that file.
[vsim]
DelayFileOpen = 1
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Simulator Variables
Variable Precedence
Variable Precedence
Note that some variables can be set in a .modelsim file (Registry in Windows) or a .ini file. A variable set in the .modelsim file takes precedence over the same variable set in a .ini file. For example, assume you have the following line in your modelsim.ini file:
TranscriptFile = transcript
And assume you have the following line in your .modelsim file:
set PrefMain(file) {}
In this case the setting in the .modelsim file overrides that in the modelsim.ini file, and a transcript file will not be produced.
Simulator State Variables
Unlike other variables that must be explicitly set, simulator state variables return a value relative to the current simulation. Simulator state variables can be useful in commands, especially when used within ModelSim DO files (macros). The variables are referenced in commands by prefixing the name with a dollar sign ($).
argc
This variable returns the total number of parameters passed to the current macro.
architecture
This variable returns the name of the top-level architecture currently being simulated; for a configuration or Verilog module, this variable returns an empty string.
configuration
This variable returns the name of the top-level configuration currently being simulated; returns an empty string if no configuration.
delta
This variable returns the number of the current simulator iteration.
entity
This variable returns the name of the top-level VHDL entity or Verilog module currently being simulated.
library
This variable returns the library name for the current region.
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MacroNestingLevel
This variable returns the current depth of macro call nesting.
n
This variable represents a macro parameter, where n can be an integer in the range 1-9.
Now
This variable always returns the current simulation time with time units (e.g., 110,000 ns) Note: will return a comma between thousands.
now
This variable when time resolution is a unary unit (i.e., 1ns, 1ps, 1fs): returns the current simulation time without time units (e.g., 100000) when time resolution is a multiple of the unary unit (i.e., 10ns, 100ps, 10fs): returns the current simulation time with time units (e.g. 110000 ns)
Note: will not return comma between thousands.
resolution
This variable returns the current simulation time resolution.
Referencing Simulator State Variables
Variable values may be referenced in simulator commands by preceding the variable name with a dollar sign ($). For example, to use the now and resolution variables in an echo command type:
echo "The time is $now $resolution."
Depending on the current simulator state, this command could result in:
The time is 12390 ps 10ps.
If you do not want the dollar sign to denote a simulator variable, precede it with a "\". For example, \$now will not be interpreted as the current simulator time.
Special Considerations for the now Variable
For the when command, special processing is performed on comparisons involving the now variable. If you specify "when {$now=100}...", the simulator will stop at time 100 regardless of the multiplier applied to the time resolution.
You must use 64-bit time operators if the time value of now will exceed 2147483647 (the limit of 32-bit numbers). For example:
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.
.
.
if { [gtTime $now 2us] } {
See
Simulator Tcl Time Commands for details on 64-bit time operators.
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Appendix B
Location Mapping
Pathnames to source files are recorded in libraries by storing the working directory from which the compile is invoked and the pathname to the file as specified in the invocation of the compiler. The pathname may be either a complete pathname or a relative pathname.
Referencing Source Files with Location Maps
ModelSim tools that reference source files from the library locate a source file as follows:
•
If the pathname stored in the library is complete, then this is the path used to reference the file.
•
If the pathname is relative, then the tool looks for the file relative to the current working directory. If this file does not exist, then the path relative to the working directory stored in the library is used.
This method of referencing source files generally works fine if the libraries are created and used on a single system. However, when multiple systems access a library across a network, the physical pathnames are not always the same and the source file reference rules do not always work.
Using Location Mapping
Location maps are used to replace prefixes of physical pathnames in the library with environment variables. The location map defines a mapping between physical pathname prefixes and environment variables.
ModelSim tools open the location map file on invocation if the
environment variable is set. If MGC_LOCATION_MAP is not set, ModelSim will look for a file named "mgc_location_map" in the following locations, in order:
• the current directory
• your home directory
• the directory containing the ModelSim binaries
• the ModelSim installation directory
Use these two steps to map your files:
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Referencing Source Files with Location Maps
1. Set the environment variable MGC_LOCATION_MAP to the path to your location map file.
2. Specify the mappings from physical pathnames to logical pathnames:
$SRC
/home/vhdl/src
/usr/vhdl/src
$IEEE
/usr/modeltech/ieee
Pathname Syntax
The logical pathnames must begin with $ and the physical pathnames must begin with /. The logical pathname is followed by one or more equivalent physical pathnames. Physical pathnames are equivalent if they refer to the same physical directory (they just have different pathnames on different systems).
How Location Mapping Works
When a pathname is stored, an attempt is made to map the physical pathname to a path relative to a logical pathname. This is done by searching the location map file for the first physical pathname that is a prefix to the pathname in question. The logical pathname is then substituted for the prefix. For example, "/usr/vhdl/src/test.vhd" is mapped to "$SRC/test.vhd". If a mapping can be made to a logical pathname, then this is the pathname that is saved. The path to a source file entry for a design unit in a library is a good example of a typical mapping.
For mapping from a logical pathname back to the physical pathname, ModelSim expects an environment variable to be set for each logical pathname (with the same name). ModelSim reads the location map file when a tool is invoked. If the environment variables corresponding to logical pathnames have not been set in your shell, ModelSim sets the variables to the first physical pathname following the logical pathname in the location map. For example, if you don't set the SRC environment variable, ModelSim will automatically set it to "/home/vhdl/src".
Mapping with TCL Variables
Two Tcl variables may also be used to specify alternative source-file paths; SourceDir and
SourceMap. You would define these variables in a modelsim.tcl file. See the
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Appendix C
Error and Warning Messages
Message System
The ModelSim message system helps you identify and troubleshoot problems while using the application. The messages display in a standard format in the Transcript pane. Accordingly, you can also access them from a saved transcript file (see
Saving the Transcript File for more
details).
Message Format
The format for the messages is:
** <SEVERITY LEVEL>: ([<Tool>[-<Group>]]-<MsgNum>) <Message>
•
SEVERITY LEVEL — may be one of the following:
severity level
Note
Warning
Table C-1. Severity Level Types meaning
This is an informational message.
There may be a problem that will affect the accuracy of your results.
The tool cannot complete the operation.
The tool cannot complete execution.
Error
Fatal
•
Tool — indicates which ModelSim tool was being executed when the message was generated. For example tool could be vcom, vdel, vsim, etc.
•
Group — indicates the topic to which the problem is related. For example group could be FLI, PLI, VCD, etc.
Example
# ** Error: (vsim-PLI-3071) ./src/19/testfile(77): $fdumplimit : Too few arguments.
Getting More Information
Each message is identified by a unique MsgNum id. You can access additional information about a message using the unique id and the verror command. For example:
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Suppressing Warning Messages
% verror 3071
Message # 3071:
Not enough arguments are being passed to the specified system task or function.
Changing Message Severity Level
You can suppress or change the severity of notes, warnings, and errors that come from vcom,
vlog, and vsim. You cannot change the severity of or suppress Fatal or Internal messages.
There are two ways to modify the severity of or suppress notes, warnings, and errors:
•
Use the -error, -fatal, -note, -suppress, and -warning arguments to vcom , vlog , or vsim .
See the command descriptions in the Reference Manual for details on those arguments.
•
Set a permanent default in the [msg_system] section of the modelsim.ini file. See
Simulator Control Variables for more information.
Suppressing Warning Messages
You can suppress some warning messages. For example, you may receive warning messages about unbound components about which you are not concerned.
Suppressing VCOM Warning Messages
Use the -nowarn <number> argument to
vcom
to suppress a specific warning message. For example: vcom -nowarn 1 suppresses unbound component warning messages.
Alternatively, warnings may be disabled for all compiles via the modelsim.ini file (see
The warning message numbers are:
1 = unbound component
2 = process without a wait statement
3 = null range
4 = no space in time literal
5 = multiple drivers on unresolved signal
6 = compliance checks
7 = optimization messages
8 = lint checks
9 = signal value dependency at elaboration
10 = VHDL93 constructs in VHDL87 code
14 = locally static error deferred until simulation run
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Exit Codes
These numbers are category-of-warning message numbers. They are unrelated to vcom arguments that are specified by numbers, such as vcom -87 – which disables support for
VHDL-1993 and 2002.
Suppressing VLOG Warning Messages
Use the +nowarn<CODE> argument to
vlog
to suppress a specific warning message.
Warnings that can be disabled include the <CODE> name in square brackets in the warning message. For example: vlog +nowarnDECAY suppresses decay warning messages.
Suppressing VSIM Warning Messages
Use the +nowarn<CODE> argument to
vsim
to suppress a specific warning message.
Warnings that can be disabled include the <CODE> name in square brackets in the warning message. For example: vsim +nowarnTFMPC suppresses warning messages about too few port connections.
Exit Codes
The table below describes exit codes used by ModelSim tools.
8
9
5
6
3
4
7
1
2
Exit code
0
Table C-2. Exit Codes
Description
Normal (non-error) return
Incorrect invocation of tool
Previous errors prevent continuing
Cannot create a system process (execv, fork, spawn, etc.)
Licensing problem
Cannot create/open/find/read/write a design library
Cannot create/open/find/read/write a design unit
Cannot open/read/write/dup a file (open, lseek, write, mmap, munmap, fopen, fdopen, fread, dup2, etc.)
File is corrupted or incorrect type, version, or format of file
Memory allocation error
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205
206
208
210
102
111
202
204
211
213
214
215
90
99
100
101
42
43
44
45
Error and Warning Messages
Exit Codes
Exit code
10
11
12
13
14
15
16
19
Table C-2. Exit Codes
Description
General language semantics error
General language syntax error
Problem during load or elaboration
Problem during restore
Problem during refresh
Communication problem (Cannot create/read/write/close pipe/socket)
Version incompatibility
License manager not found/unreadable/unexecutable
(vlm/mgvlm)
Lost license
License read/write failure
Modeltech daemon license checkout failure #44
Modeltech daemon license checkout failure #45
Assertion failure (SEVERITY_QUIT)
Unexpected error in tool
GUI Tcl initialization failure
GUI Tk initialization failure
GUI IncrTk initialization failure
X11 display error
Interrupt (SIGINT)
Illegal instruction (SIGILL)
Trace trap (SIGTRAP)
Abort (SIGABRT)
Floating point exception (SIGFPE)
Bus error (SIGBUS)
Segmentation violation (SIGSEGV)
Write on a pipe with no reader (SIGPIPE)
Alarm clock (SIGALRM)
Software termination signal from kill (SIGTERM)
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Miscellaneous Messages
Exit code
216
217
218
230
231
Table C-2. Exit Codes
Description
User-defined signal 1 (SIGUSR1)
User-defined signal 2 (SIGUSR2)
Child status change (SIGCHLD)
Exceeded CPU limit (SIGXCPU)
Exceeded file size limit (SIGXFSZ)
Miscellaneous Messages
This section describes miscellaneous messages which may be associated with ModelSim.
Compilation of DPI Export TFs Error
# ** Fatal: (vsim-3740) Can't locate a C compiler for compilation of
DPI export tasks/functions.
•
Description — ModelSim was unable to locate a C compiler to compile the DPI exported tasks or functions in your design.
•
Suggested Action —Make sure that a C compiler is visible from where you are running the simulation.
Empty port name warning
# ** WARNING: [8] <path/file_name>: empty port name in port list.
•
Description — ModelSim reports these warnings if you use the -lint argument to vlog . It reports the warning for any NULL module ports.
•
Suggested action — If you wish to ignore this warning, do not use the -lint argument.
Lock message
waiting for lock by user@user. Lockfile is <library_path>/_lock
•
Description — The _lock file is created in a library when you begin a compilation into that library, and it is removed when the compilation completes. This prevents simultaneous updates to the library. If a previous compile did not terminate properly,
ModelSim may fail to remove the _lock file.
•
Suggested action — Manually remove the _lock file after making sure that no one else is actually using that library.
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Miscellaneous Messages
Metavalue detected warning
Warning: NUMERIC_STD.">": metavalue detected, returning FALSE
•
Description — This warning is an assertion being issued by the IEEE numeric_std package. It indicates that there is an 'X' in the comparison.
•
Suggested action — The message does not indicate which comparison is reporting the problem since the assertion is coming from a standard package. To track the problem, note the time the warning occurs, restart the simulation, and run to one time unit before the noted time. At this point, start stepping the simulator until the warning appears. The location of the blue arrow in a Source window will be pointing at the line following the line with the comparison.
These messages can be turned off by setting the NumericStdNoWarnings variable to 1 from the command line or in the modelsim.ini file.
Sensitivity list warning
signal is read by the process but is not in the sensitivity list
•
Description — ModelSim outputs this message when you use the -check_synthesis argument to vcom . It reports the warning for any signal that is read by the process but is not in the sensitivity list.
•
Suggested action — There are cases where you may purposely omit signals from the sensitivity list even though they are read by the process. For example, in a strictly sequential process, you may prefer to include only the clock and reset in the sensitivity list because it would be a design error if any other signal triggered the process. In such cases, your only option is to not use the -check_synthesis argument.
Tcl Initialization error 2
Tcl_Init Error 2 : Can't find a usable Init.tcl in the following directories :
./../tcl/tcl8.3 .
•
Description — This message typically occurs when the base file was not included in a
Unix installation. When you install ModelSim, you need to download and install 3 files from the ftp site. These files are: modeltech-base.tar.gz
modeltech-docs.tar.gz
modeltech-<platform>.exe.gz
If you install only the <platform> file, you will not get the Tcl files that are located in the base file.
This message could also occur if the file or directory was deleted or corrupted.
•
Suggested action — Reinstall ModelSim with all three files.
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Miscellaneous Messages
Too few port connections
# ** Warning (vsim-3017): foo.v(1422): [TFMPC] - Too few port connections. Expected 2, found 1.
# Region: /foo/tb
•
Description — This warning occurs when an instantiation has fewer port connections than the corresponding module definition. The warning doesn’t necessarily mean anything is wrong; it is legal in Verilog to have an instantiation that doesn’t connect all of the pins. However, someone that expects all pins to be connected would like to see such a warning.
Here are some examples of legal instantiations that will and will not cause the warning message.
Module definition: module foo (a, b, c, d);
Instantiation that does not connect all pins but will not produce the warning: foo inst1(e, f, g, ); // positional association foo inst1(.a(e), .b(f), .c(g), .d()); // named association
Instantiation that does not connect all pins but will produce the warning: foo inst1(e, f, g); // positional association foo inst1(.a(e), .b(f), .c(g)); // named association
Any instantiation above will leave pin d unconnected but the first example has a placeholder for the connection. Here’s another example: foo inst1(e, , g, h); foo inst1(.a(e), .b(), .c(g), .d(h));
•
Suggested actions — o
Check that there is not an extra comma at the end of the port list. (e.g., model(a,b,) ).
The extra comma is legal Verilog and implies that there is a third port connection that is unnamed.
o
If you are purposefully leaving pins unconnected, you can disable these messages using the +nowarnTFMPC argument to vsim.
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Enforcing Strict 1076 Compliance
VSIM license lost
Console output:
Signal 0 caught... Closing vsim vlm child.
vsim is exiting with code 4
FATAL ERROR in license manager transcript/vsim output:
# ** Error: VSIM license lost; attempting to re-establish.
# Time: 5027 ns Iteration: 2
# ** Fatal: Unable to kill and restart license process.
# Time: 5027 ns Iteration: 2
•
Description — ModelSim queries the license server for a license at regular intervals.
Usually these "License Lost" error messages indicate that network traffic is high, and communication with the license server times out.
•
Suggested action — Anything you can do to improve network communication with the license server will probably solve or decrease the frequency of this problem.
Enforcing Strict 1076 Compliance
The optional -pedanticerrors argument to vcom enforces strict compliance to the IEEE 1076
LRM in the cases listed below. The default behavior for these cases is to issue an insuppressible warning message. If you compile with -pedanticerrors, the warnings change to an error, unless otherwise noted. Descriptions in quotes are actual warning/error messages emitted by vcom. As noted, in some cases you can suppress the warning using -nowarn [level].
•
Type conversion between array types, where the element subtypes of the arrays do not have identical constraints.
•
"Extended identifier terminates at newline character (0xa)."
•
"Extended identifier contains non-graphic character 0x%x."
•
"Extended identifier \"%s\" contains no graphic characters."
•
"Extended identifier \"%s\" did not terminate with backslash character."
•
"An abstract literal and an identifier must have a separator between them."
This is for forming physical literals, which comprise an optional numeric literal, followed by a separator, followed by an identifier (the unit name). Warning is level 4, which means "-nowarn 4" will suppress it.
•
In VHDL 1993 or 2002, a subprogram parameter was declared using VHDL 1987 syntax (which means that it was a class VARIABLE parameter of a file type, which is the only way to do it in VHDL 1987 and is illegal in later VHDLs). Warning is level 10.
•
"Shared variables must be of a protected type." Applies to VHDL 2002 only.
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Enforcing Strict 1076 Compliance
•
Expressions evaluated during elaboration cannot depend on signal values. Warning is level 9.
•
"Non-standard use of output port '%s' in PSL expression." Warning is level 11.
•
"Non-standard use of linkage port '%s' in PSL expression." Warning is level 11.
•
Type mark of type conversion expression must be a named type or subtype, it can't have a constraint on it.
•
When the actual in a PORT MAP association is an expression, it must be a (globally) static expression. The port must also be of mode IN.
•
The expression in the CASE and selected signal assignment statements must follow the rules given in 8.8 of the LRM. In certain cases we can relax these rules, but
-pedanticerrors forces strict compliance.
•
A CASE choice expression must be a locally static expression. We allow it to be only globally static, but -pedanticerrors will check that it is locally static. Same rule for selected signal assignment statement choices. Warning level is 8.
•
When making a default binding for a component instantiation, ModelSim's non-standard search rules found a matching entity. VHDL 2002 LRM Section 5.2.2 spells out the standard search rules. Warning level is 1.
•
Both FOR GENERATE and IF GENERATE expressions must be globally static. We allow non-static expressions unless -pedanticerrors is present.
•
When the actual part of an association element is in the form of a conversion function call [or a type conversion], and the formal is of an unconstrained array type, the return type of the conversion function [type mark of the type conversion] must be of a constrained array subtype. We relax this (with a warning) unless -pedanticerrors is present when it becomes an error.
•
OTHERS choice in a record aggregate must refer to at least one record element.
•
In an array aggregate of an array type whose element subtype is itself an array, all expressions in the array aggregate must have the same index constraint, which is the element's index constraint. No warning is issued; the presence of -pedanticerrors will produce an error.
•
Non-static choice in an array aggregate must be the only choice in the only element association of the aggregate.
•
The range constraint of a scalar subtype indication must have bounds both of the same type as the type mark of the subtype indication.
•
The index constraint of an array subtype indication must have index ranges each of whose both bounds must be of the same type as the corresponding index subtype.
•
When compiling VHDL 1987, various VHDL 1993 and 2002 syntax is allowed. Use
-pedanticerrors to force strict compliance. Warnings are all level 10.
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Appendix D
Verilog PLI/VPI/DPI
This appendix describes the ModelSim implementation of the Verilog PLI (Programming
Language Interface), VPI (Verilog Procedural Interface) and SystemVerilog DPI (Direct
Programming Interface). These three interfaces provide a mechanism for defining tasks and functions that communicate with the simulator through a C procedural interface. There are many third party applications available that interface to Verilog simulators through the PLI (see
Third Party PLI Applications ). In addition, you may write your own PLI/VPI/DPI applications.
Implementation Information
ModelSim Verilog implements the PLI as defined in the IEEE Std 1364-2001, with the exception of the acc_handle_datapath() routine. We did not implement the
acc_handle_datapath() routine because the information it returns is more appropriate for a static timing analysis tool.
The VPI is partially implemented as defined in the IEEE Std 1364-2005. The list of currently supported functionality can be found in the following file:
<install_dir>/modeltech/docs/technotes/Verilog_VPI.note
ModelSim SystemVerilog implements DPI as defined in IEEE Std P1800-2005.
The IEEE Std 1364 is the reference that defines the usage of the PLI/VPI routines, and the IEEE
Std P1800-2005 Language Reference Manual (LRM) defines the usage of DPI routines. This manual describes only the details of using the PLI/VPI/DPI with ModelSim Verilog and
SystemVerilog.
g++ Compiler Support for use with PLI/VPI/DPI
We strongly encourage that unless you have a reason to do otherwise, you should use the builtin g++ compiler that is shipped with the ModelSim compiler to compile your C++ code. This is the version that has been tested and is supported for any given release.
Specifying Your Own g++ Compiler
If you must use a different g++ compiler, other than that shipped with ModelSim, you need to set a variable in your modelsim.ini file, as follows:
CppPath = /usr/bin/g++
to point to the desired g++ version.
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Registering PLI Applications
Registering PLI Applications
Each PLI application must register its system tasks and functions with the simulator, providing the name of each system task and function and the associated callback routines. Since many PLI applications already interface to Verilog-XL, ModelSim Verilog PLI applications make use of the same mechanism to register information about each system task and function in an array of s_tfcell structures. This structure is declared in the veriuser.h include file as follows: typedef int (*p_tffn)(); typedef struct t_tfcell { short type;/* USERTASK, USERFUNCTION, or USERREALFUNCTION */ short data;/* passed as data argument of callback function */ p_tffn checktf; /* argument checking callback function */ p_tffn sizetf; /* function return size callback function */ p_tffn calltf; /* task or function call callback function */ p_tffn misctf; /* miscellaneous reason callback function */ char *tfname;/* name of system task or function */
/* The following fields are ignored by ModelSim Verilog */ int forwref; char *tfveritool; char *tferrmessage; int hash; struct t_tfcell *left_p; struct t_tfcell *right_p; char *namecell_p; int warning_printed;
} s_tfcell, *p_tfcell;
The various callback functions (checktf, sizetf, calltf, and misctf) are described in detail in the
IEEE Std 1364. The simulator calls these functions for various reasons. All callback functions are optional, but most applications contain at least the calltf function, which is called when the system task or function is executed in the Verilog code. The first argument to the callback functions is the value supplied in the data field (many PLI applications don't use this field). The type field defines the entry as either a system task (USERTASK) or a system function that returns either a register (USERFUNCTION) or a real (USERREALFUNCTION). The tfname field is the system task or function name (it must begin with $). The remaining fields are not used by ModelSim Verilog.
On loading of a PLI application, the simulator first looks for an init_usertfs function, and then a veriusertfs array. If init_usertfs is found, the simulator calls that function so that it can call mti_RegisterUserTF() for each system task or function defined. The mti_RegisterUserTF() function is declared in veriuser.h as follows: void mti_RegisterUserTF(p_tfcell usertf);
The storage for each usertf entry passed to the simulator must persist throughout the simulation because the simulator de-references the usertf pointer to call the callback functions. We recommend that you define your entries in an array, with the last entry set to 0. If the array is named veriusertfs (as is the case for linking to Verilog-XL), then you don't have to provide an
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init_usertfs function, and the simulator will automatically register the entries directly from the array (the last entry must be 0). For example, s_tfcell veriusertfs[] = {
{usertask, 0, 0, 0, abc_calltf, 0, "$abc"},
{usertask, 0, 0, 0, xyz_calltf, 0, "$xyz"},
{0} /* last entry must be 0 */
};
Alternatively, you can add an init_usertfs function to explicitly register each entry from the array: void init_usertfs()
{ p_tfcell usertf = veriusertfs; while (usertf->type) mti_RegisterUserTF(usertf++);
}
It is an error if a PLI shared library does not contain a veriusertfs array or an init_usertfs function.
Since PLI applications are dynamically loaded by the simulator, you must specify which applications to load (each application must be a dynamically loadable library, see
(note that on a Windows platform the file extension would be .dll):
•
As a list in the Veriuser entry in the modelsim.ini file:
Veriuser = pliapp1.so pliapp2.so pliappn.so
•
As a list in the PLIOBJS environment variable:
% setenv PLIOBJS "pliapp1.so pliapp2.so pliappn.so"
•
As a -pli argument to the simulator (multiple arguments are allowed):
-pli pliapp1.so -pli pliapp2.so -pli pliappn.so
The various methods of specifying PLI applications can be used simultaneously. The libraries are loaded in the order listed above. Environment variable references can be used in the paths to the libraries in all cases.
Registering VPI Applications
Each VPI application must register its system tasks and functions and its callbacks with the simulator. To accomplish this, one or more user-created registration routines must be called at simulation startup. Each registration routine should make one or more calls to vpi_register_systf() to register user-defined system tasks and functions and vpi_register_cb() to register callbacks. The registration routines must be placed in a table named
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vlog_startup_routines so that the simulator can find them. The table must be terminated with a 0 entry.
Example D-1. VPI Application Registration
PLI_INT32 MyFuncCalltf( PLI_BYTE8 *user_data )
{ ... }
PLI_INT32 MyFuncCompiletf( PLI_BYTE8 *user_data )
{ ... }
PLI_INT32 MyFuncSizetf( PLI_BYTE8 *user_data )
{ ... }
PLI_INT32 MyEndOfCompCB( p_cb_data cb_data_p )
{ ... }
PLI_INT32 MyStartOfSimCB( p_cb_data cb_data_p )
{ ... } void RegisterMySystfs( void )
{ vpiHandle tmpH; s_cb_data callback;
s_vpi_systf_data systf_data;
systf_data.type = vpiSysFunc;
systf_data.sysfunctype = vpiSizedFunc;
systf_data.tfname = "$myfunc";
systf_data.calltf = MyFuncCalltf;
systf_data.compiletf = MyFuncCompiletf;
systf_data.sizetf = MyFuncSizetf;
systf_data.user_data = 0;
tmpH = vpi_register_systf( &systf_data ); vpi_free_object(tmpH);
callback.reason = cbEndOfCompile;
callback.cb_rtn = MyEndOfCompCB;
callback.user_data = 0;
tmpH = vpi_register_cb( &callback ); vpi_free_object(tmpH); callback.reason = cbStartOfSimulation;
callback.cb_rtn = MyStartOfSimCB;
callback.user_data = 0; tmpH = vpi_register_cb( &callback ); vpi_free_object(tmpH);
} void (*vlog_startup_routines[ ] ) () = {
RegisterMySystfs,
0 /* last entry must be 0 */
};
Loading VPI applications into the simulator is the same as described in
.
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Using PLI and VPI Together
PLI and VPI applications can co-exist in the same application object file. In such cases, the applications are loaded at startup as follows:
•
If an init_usertfs() function exists, then it is executed and only those system tasks and functions registered by calls to mti_RegisterUserTF() will be defined.
•
If an init_usertfs() function does not exist but a veriusertfs table does exist, then only those system tasks and functions listed in the veriusertfs table will be defined.
•
If an init_usertfs() function does not exist and a veriusertfs table does not exist, but a vlog_startup_routines table does exist, then only those system tasks and functions and callbacks registered by functions in the vlog_startup_routines table will be defined.
As a result, when PLI and VPI applications exist in the same application object file, they must be registered in the same manner. VPI registration functions that would normally be listed in a vlog_startup_routines table can be called from an init_usertfs() function instead.
Registering DPI Applications
DPI applications do not need to be registered. However, each DPI imported or exported task or function must be identified using SystemVerilog ‘import “DPI-C”’ or ‘export “DPI-C”’syntax.
Examples of the syntax follow: export "DPI-C" task t1; task t1(input int i, output int o);
.
.
.
end task import "DPI-C" function void f1(input int i, output int o);
Your code must provide imported functions or tasks, compiled with an external compiler. An imported task must return an int value, "1" indicating that it is returning due to a disable, or "0" indicating otherwise.
These imported functions or objects may then be loaded as a shared library into the simulator with either the command line option -sv_lib <lib> or -sv_liblist <bootstrap_file>. For example,
vlog dut.v
gcc -shared -Bsymbolic -o imports.so imports.c
vsim -sv_lib imports top -do <do_file>
The -sv_lib option specifies the shared library name, without an extension. A file extension is added by the tool, as appropriate to your platform. For a list of file extensions accepted by platform, see
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You can also use the command line options -sv_root and -sv_liblist to control the process for loading imported functions and tasks. These options are defined in the IEEE Std P1800-2005
LRM.
DPI Use Flow
Correct use of ModelSim DPI depends on the flow presented in this section.
Figure D-1. DPI Use Flow Diagram
Step 1 Create header
.v
vlog
vlog -dpiheader dpiheader.h
dpiheader.h
vsim
Step 1.5 Required for
Windows only vsim -dpiexportobj <exportobj>
Step 2 Include header
#include "dpiheader.h"
.c
<exportobj>
gcc
C compiler mtipli.lib
.o
compiled user code
ld/link
loader/linker
Step 3
Compile and load/link
C code
<test>.so
shared object
vsim
Step 4 Simulate vsim -sv_lib <test>
1. Run vlog to generate a dpiheader.h file.
This file defines the interface between C and ModelSim for exported and imported tasks and functions. Though the dpiheader.h is a user convenience file rather than requirement, including dpiheader.h in your C code can immediately solve problems
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DPI Use Flow
caused by an improperly defined interface. An example command for creating the header file would be:
vlog -dpiheader <dpiheader>.h files.v
2. Required for Windows only; Run a preliminary invocation of vsim with the
-dpiexportobj argument.
Because of limitations with the linker/loader provided on Windows, this additional step is required. You must create the exported task/function compiled object file (exportobj) by running a preliminary vsim command, such as:
vsim -dpiexportobj exportobj top
3. Include the dpiheader.h file in your C code.
ModelSim recommends that any user DPI C code that accesses exported tasks/functions, or defines imported tasks/functions, will include the dpiheader.h file. This allows the C compiler to verify the interface between C and ModelSim.
4. Compile the C code into a shared object.
Compile your code, providing any .a or other .o files required.
For Windows users — In this step, the object file needs to be bound together with the
.obj that you created using the -dpiexportobj argument, into a single .dll file.
5. Simulate the design.
When simulating, specify the name of the imported DPI C shared object (according to the SystemVerilog LRM). For example:
vsim -sv_lib <test> top
When Your DPI Export Function is Not Getting Called
This issue can arise in your C code due to the way the C linker resolves symbols. It happens if a name you choose for a SystemVerilog export function happens to match a function name in a custom, or even standard C library. In this case, your C compiler will bind calls to the function in that C library, rather than to the export function in the SystemVerilog simulator.
The symptoms of such a misbinding can be difficult to detect. Generally, the misbound function silently returns an unexpected or incorrect value.
To determine if you have this type of name aliasing problem, consult the C library documentation (either the online help or man pages).
Simplified Import of FLI / PLI / C Library Functions
In addition to the traditional method of importing FLI / PLI / C library functions, a simplified method can be used: you can declare VPI and FLI functions as DPI-C imports. When you
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declare VPI and FLI functions as DPI-C imports, the DPI shared object is loaded at runtime automatically. Neither the C implementation of the import tf, nor the -sv_lib argument is required.
Also, on most platforms (see
Platform Specific Information ), you can declare most standard C
library functions as DPI-C imports.
The following example is processed directly, without DPI C code: package cmath;
import "DPI-C" function real sin(input real x);
import "DPI-C" function real sqrt(input real x); endpackage package fli;
import "DPI-C" function mti_Cmd(input string cmd); endpackage module top;
import cmath::*;
import fli::*;
int status, A;
initial begin
$display("sin(0.98) = %f", sin(0.98));
$display("sqrt(0.98) = %f", sqrt(0.98));
status = mti_Cmd("change A 123");
$display("A = %1d, status = %1d", A, status);
end endmodule
To simulate, you would simply enter a command such as: vsim top.
Platform Specific Information
This feature is not supported on AIX.
On Windows, only FLI and PLI commands may be imported in this fashion. C library functions are not automatically importable. They must be wrapped in user DPI C functions, which are brought into the simulator using the -sv_lib argument.
Use Model for Read-Only Work Libraries
You may want to create the work library as a read-only entity, which enables multiple users to simultaneously share the design library at runtime. The steps are as follows:
•
Windows and RS6000/RS64
On these platforms, simply change the permissions on the design library to read only by issuing a command such as "chmod -R a-w <libname>". Do this after you have finished compiling with vlog / vcom and vopt .
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•
All Other Platforms
If a design contains no DPI export tasks or functions, the work library can be changed by simply changing the permissions, as shown for win32 and rs6000/rs64 above.
For designs that contain DPI export tasks and functions, and are not run on Windows or
RS6000/RS64, by default vsim creates a shared object in directory <libname>/_dpi.
This shared object is called exportwrapper.so (Linux and Solaris) or exportwrapper.sl
(hp700, hppa64, and hpux_ia64). If you are using a read-only library, vsim must not create any objects in the library.
To prevent vsim from creating objects in the library at runtime, the vsim -dpiexportobj flow is available on all platforms. Use this flow after compilation, but before you start simulation using the design library.
An example command sequence on Linux would be:
vlib work vlog -dpiheader dpiheader.h test.sv
gcc -shared -Bsymbolic -o test.so test.c
vsim -c -dpiexportobj work/_dpi/exportwrapper top chmod -R a-w work
The library is now ready for simulation by multiple simultaneous users, as follows:
vsim top -sv_lib test
The work/_dpi/exportwrapper argument provides a basename for the shared object.
At runtime, vsim automatically checks to see if the file work/_dpi/exportwrapper.so is up-todate with respect to its C source code. If it is out of date, an error message is issued and elaboration stops.
Compiling and Linking C Applications for
PLI/VPI/DPI
The following platform-specific instructions show you how to compile and link your
PLI/VPI/DPI C applications so that they can be loaded by ModelSim. Various native C/C++ compilers are supported on different platforms. The gcc compiler is supported on all platforms.
The following PLI/VPI/DPI routines are declared in the include files located in the ModelSim
<install_dir>/modeltech/include directory:
• acc_user.h — declares the ACC routines
• veriuser.h — declares the TF routines
• vpi_user.h — declares the VPI routines
• svdpi.h — declares DPI routines
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The following instructions assume that the PLI, VPI, or DPI application is in a single source file. For multiple source files, compile each file as specified in the instructions and link all of the resulting object files together with the specified link instructions.
Although compilation and simulation switches are platform-specific, loading shared libraries is the same for all platforms. For information on loading libraries for PLI/VPI see
PLI/VPI file loading . For DPI loading instructions, see
.
For all UNIX Platforms
The information in this section applies to all UNIX platforms.
app.so
If app.so is not in your current directory, you must tell the OS where to search for the shared object. You can do this one of two ways:
•
Add a path before app.so in the command line option or control variable (The path may include environment variables.)
•
Put the path in a UNIX shell environment variable:
LD_LIBRARY_PATH_32= <library path without filename> (for Solaris/Linux 32-bit) or
LD_LIBRARY_PATH_64= <library path without filename> (for Solaris 64-bit) or
SHLIB_PATH= <library path without filename> (for HP-UX)
Correct Linking of Shared Libraries with -Bsymbolic
In the examples shown throughout this appendix, the -Bsymbolic linker option is used with the compilation (gcc or g++) or link (ld) commands to correctly resolve symbols. This option instructs the linker to search for the symbol within the local shared library and bind to that symbol if it exists. If the symbol is not found within the library, the linker searches for the symbol within the vsimk executable and binds to that symbol, if it exists.
When using the -Bsymbolic option, the linker may warn about symbol references that are not resolved within the local shared library. It is safe to ignore these warnings, provided the symbols are present in other shared libraries or the vsimk executable. (An example of such a warning would be a reference to a common API call such as vpi_printf()
).
Windows Platforms
•
Microsoft Visual C 4.1 or Later
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Compiling and Linking C Applications for PLI/VPI/DPI cl -c -I<install_dir>\modeltech\include app.c
link -dll -export:<init_function> app.obj <install_dir>\win32\mtipli.lib -out:app.dll
For the Verilog PLI, the <init_function> should be "init_usertfs". Alternatively, if there is no init_usertfs function, the <init_function> specified on the command line should be
"veriusertfs". For the Verilog VPI, the <init_function> should be
"vlog_startup_routines". These requirements ensure that the appropriate symbol is exported, and thus ModelSim can find the symbol when it dynamically loads the DLL.
When executing cl commands in a DO file, use the /NOLOGO switch to prevent the
Microsoft C compiler from writing the logo banner to stderr. Writing the logo causes Tcl to think an error occurred.
•
MinGW gcc 3.2.3
gcc -c -I<install_dir>\include app.c
gcc -shared -Bsymbolic -o app.dll app.o -L<install_dir>\win32 -lmtipli
The ModelSim tool requires the use of MinGW gcc compiler rather than the Cygwin gcc compiler. MinGW gcc is available on the ModelSim FTP site. Remember to add the path to your gcc executable in the Windows environment variables.
DPI Imports on Windows Platforms
When linking the shared objects, be sure to specify one export option for each DPI imported task or function in your linking command line. You can use the -isymfile argument from the vlog command to obtain a complete list of all imported tasks/functions expected by ModelSim.
As an alternative to specifying one -export option for each imported task or function, you can make use of the __declspec (dllexport) macro supported by Visual C. You can place this macro before every DPI import task or function declaration in your C source. All the marked functions will be available for use by vsim as DPI import tasks and functions.
DPI Flow for Exported Tasks and Functions on Windows Platforms
Since the Windows platform lacks the necessary runtime linking capabilities, you must perform an additional manual step in order to prepare shared objects containing calls to exported
SystemVerilog tasks or functions. You need to invoke a special run of vsim . The command is as follows:
vsim <top du list> -dpiexportobj <objname> <other args>
The -dpiexportobj generates an object file <objname>.obj that contains "glue" code for exported tasks and functions. You must add that object file to the link line for your .dll, listed after the other object files. For example, a link line for MinGW would be:
gcc -shared -Bsymbolic -o app.dll app.obj <objname>.obj
-L<install_dir>\modeltech\win32 -lmtipli
and a link line for Visual C would be:
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Compiling and Linking C Applications for PLI/VPI/DPI link -dll -export:<init_function> app.obj <objname>.obj\
<install_dir>\modeltech\win32\mtipli.lib -out:app.dll
32-bit Linux Platform
If your PLI/VPI/DPI application uses anything from a system library, you will need to specify that library when you link your PLI/VPI/DPI application. For example, to use the standard C library, specify ‘-lc’ to the ‘ld’ command.
• gcc compiler
gcc -c -I/<install_dir>/modeltech/include app.c
ld -shared -Bsymbolic -E -o app.so app.o -lc
If you are using ModelSim with RedHat version 7.1 or below, you also need to add the
-noinhibit-exec switch when you specify -Bsymbolic.
The compiler switch -freg-struct-return must be used when compiling any FLI application code that contains foreign functions that return real or time values.
64-bit Linux for IA64 Platform
64-bit Linux is supported on RedHat Linux Advanced Workstation 2.1 for Itanium 2.
• gcc compiler (gcc 3.2 or later)
gcc -c -fPIC -I/<install_dir>/modeltech/include app.c
ld -shared -Bsymbolic -E --allow-shlib-undefined -o app.so app.o
If your PLI/VPI/DPI application requires a user or vendor-supplied C library, or an additional system library, you will need to specify that library when you link your
PLI/VPI/DPI application. For example, to use the system math library libm, specify -lm to the ld command:
gcc -c -fPIC -I/<install_dir>/modeltech/include math_app.c
ld -shared -Bsymbolic -E --allow-shlib-undefined -o math_app.so math_app.o -lm
64-bit Linux for Opteron/Athlon 64 and EM64T Platforms
64-bit Linux is supported on RedHat Linux EWS 3.0 for Opteron/Athlon 64 and EM64T.
• gcc compiler (gcc 3.2 or later)
gcc -c -fPIC -I/<install_dir>/modeltech/include app.c
ld -shared -Bsymbolic -E --allow-shlib-undefined -o app.so app.o
To compile for 32-bit operation, specify the -m32 argument on the gcc command line.
If your PLI/VPI/DPI application requires a user or vendor-supplied C library, or an additional system library, you will need to specify that library when you link your
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PLI/VPI/DPI application. For example, to use the system math library libm, specify -lm to the ld command:
gcc -c -fPIC -I/<install_dir>/modeltech/include math_app.c
ld -shared -Bsymbolic -E --allow-shlib-undefined -o math_app.so math_app.o -lm
32-bit Solaris Platform
If your PLI/VPI/DPI application uses anything from a system library, you will need to specify that library when you link your PLI/VPI/DPI application. For example, to use the standard C library, specify ‘-lc’ to the ‘ld’ command.
• gcc compiler
gcc -c -I/<install_dir>/modeltech/include app.c
ld -G -Bsymbolic -o app.so app.o -lc
• cc compiler
cc -c -I/<install_dir>/modeltech/include app.c
ld -G -Bsymbolic -o app.so app.o -lc
64-bit Solaris Platform
• gcc compiler
gcc -c -I<install_dir>/modeltech/include -m64 -fPIC app.c
gcc -shared -Bsymbolic -o app.so -m64 app.o
This was tested with gcc 3.2.2. You may need to add the location of libgcc_s.so.1 to the
LD_LIBRARY_PATH_64 environment variable.
• cc compiler
cc -v -xarch=v9 -O -I<install_dir>/modeltech/include -c app.c
ld -G -Bsymbolic app.o -o app.so
32-bit HP700 Platform
A shared library is created by creating object files that contain position-independent code (use the +z or -fPIC compiler argument) and by linking as a shared library (use the -b linker argument).
If your PLI/VPI/DPI application uses anything from a system library, you’ll need to specify that library when you link your PLI/VPI/DPI application. For example, to use the standard C library, specify ‘-lc’ to the ‘ld’ command.
• gcc compiler
gcc -c -fPIC -I/<install_dir>/modeltech/include app.c
ld -b -o app.sl app.o -lc
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Note that -fPIC may not work with all versions of gcc.
• cc compiler
cc -c +z +DD32 -I/<install_dir>/modeltech/include app.c
ld -b -o app.sl app.o -lc
64-bit HP Platform
• cc compiler
cc -v +DD64 -O -I<install_dir>/modeltech/include -c app.c
ld -b -o app.sl app.o -lc
64-bit HP for IA64 Platform
• cc compiler (/opt/ansic/bin/cc, /usr/ccs/bin/ld)
cc -c +DD64 -I/<install_dir>/modeltech/include app.c
ld -b -o app.sl app.o
If your PLI/VPI/DPI application requires a user or vendor-supplied C library, or an additional system library, you will need to specify that library when you link your
PLI/VPI/DPI application. For example, to use the system math library, specify '-lm' to the 'ld' command:
cc -c +DD64 -I/<install_dir>/modeltech/include math_app.c
ld -b -o math_app.sl math_app.o -lm
32-bit IBM RS/6000 Platform
ModelSim loads shared libraries on the IBM RS/6000 workstation. The shared library must import ModelSim's PLI/VPI/DPI symbols, and it must export the PLI or VPI application’s initialization function or table. The ModelSim tool’s export file is located in the ModelSim installation directory in rs6000/mti_exports.
If your PLI/VPI/DPI application uses anything from a system library, you’ll need to specify that library when you link your PLI/VPI/DPI application. For example, to use the standard C library, specify ‘-lc’ to the ‘ld’ command. The resulting object must be marked as shared reentrant using these gcc or cc compiler commands for AIX 4.x:
• gcc compiler
gcc -c -I/<install_dir>/modeltech/include app.c
ld -o app.sl app.o -bE:app.exp \
-bI:/<install_dir>/modeltech/rs6000/mti_exports -bM:SRE -bnoentry -lc
• cc compiler
cc -c -I/<install_dir>/modeltech/include app.c
ld -o app.sl app.o -bE:app.exp \
-bI:/<install_dir>/modeltech/rs6000/mti_exports -bM:SRE -bnoentry -lc
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Compiling and Linking C Applications for PLI/VPI/DPI
The app.exp file must export the PLI/VPI initialization function or table. For the PLI, the exported symbol should be "init_usertfs". Alternatively, if there is no init_usertfs function, then the exported symbol should be "veriusertfs". For the VPI, the exported symbol should be
"vlog_startup_routines". These requirements ensure that the appropriate symbol is exported, and thus ModelSim can find the symbol when it dynamically loads the shared object.
DPI Imports on 32-bit IBM RS/6000 Platform
When linking the shared objects, be sure to specify -bE:<isymfile> option on the link command line. <isymfile> is the name of the file generated by the-isymfile argument to the vlog command. Once you have created the <isymfile>, it contains a complete list of all imported tasks and functions expected by ModelSim.
DPI Flow for Exported Tasks and Functions on 32-bit IBM RS/6000 Platform
Since the RS6000 platform lacks the necessary runtime linking capabilities, you must perform an additional manual step in order to prepare shared objects containing calls to exported
SystemVerilog tasks or functions shared object file. You need to invoke a special run of vsim .
The command is as follows:
vsim <top du list> -dpiexportobj <objname> <other args>
The -dpiexportobj generates the object file <objname>.o that contains "glue" code for exported tasks and functions. You must add that object file to the link line, listed after the other object files. For example, a link line would be:
ld -o app.so app.o <objname>.o
-bE:<isymfile> -bI:/<install_dir>/modeltech/rs6000/mti_exports -bM:SRE -bnoentry -lc
64-bit IBM RS/6000 Platform
Only versions 5.1 and later of AIX support the 64-bit platform. A gcc 64-bit compiler is not available at this time.
•
VisualAge cc compiler
cc -c -q64 -I/<install_dir>/modeltech/include app.c
ld -o app.s1 app.o -b64 -bE:app.exports \
-bI:/<install_dir>/modeltech/rs64/mti_exports -bM:SRE -bnoentry -lc
DPI Imports on 64-bit IBM RS/6000 Platform
When linking the shared objects, be sure to specify -bE:<isymfile> option on the link command line. <isymfile> is the name of the file generated by the-isymfile argument to the vlog command. Once you have created the <isymfile>, it contains a complete list of all imported tasks and functions expected by ModelSim.
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DPI Flow for Exported Tasks and Functions on 64-bit IBM RS/6000 Platform
Since the RS6000 platform lacks the necessary runtime linking capabilities, you must perform an additional manual step in order to prepare shared objects containing calls to exported
SystemVerilog tasks or functions shared object file. You need to invoke a special run of vsim .
The command is as follows:
vsim <top du list> -dpiexportobj <objname> <other args>
The -dpiexportobj generates the object file <objname>.o that contains "glue" code for exported tasks and functions. You must add that object file to the link line, listed after the other object files. For example, a link line would be:
ld -o app.dll app.o <objname>.o
-bE:<isymfile> -bI:/<install_dir>/modeltech/rs6000/mti_exports -bM:SRE
-bnoentry -lc
Compiling and Linking C++ Applications for
PLI/VPI/DPI
ModelSim does not have direct support for any language other than standard C; however, C++ code can be loaded and executed under certain conditions.
Since ModelSim's PLI/VPI/DPI functions have a standard C prototype, you must prevent the
C++ compiler from mangling the PLI/VPI/DPI function names. This can be accomplished by using the following type of extern: extern "C"
{
<PLI/VPI/DPI application function prototypes>
}
The header files veriuser.h, acc_user.h, and vpi_user.h, svdpi.h, and dpiheader.h already include this type of extern. You must also put the PLI/VPI/DPI shared library entry point
(veriusertfs, init_usertfs, or vlog_startup_routines) inside of this type of extern.
The following platform-specific instructions show you how to compile and link your
PLI/VPI/DPI C++ applications so that they can be loaded by ModelSim.
Although compilation and simulation switches are platform-specific, loading shared libraries is the same for all platforms. For information on loading libraries, see
For PLI/VPI only
If app.so is not in your current directory you must tell Solaris where to search for the shared object. You can do this one of two ways:
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•
Add a path before app.so in the foreign attribute specification. (The path may include environment variables.)
•
Put the path in a UNIX shell environment variable:
LD_LIBRARY_PATH_32= <library path without filename> (32-bit) or
LD_LIBRARY_PATH_64= <library path without filename> (64-bit)
Windows Platforms
•
Microsoft Visual C++ 4.1 or Later
cl -c [-GX] -I<install_dir>\modeltech\include app.cxx
link -dll -export:<init_function> app.obj
<install_dir>\modeltech\win32\mtipli.lib /out:app.dll
The -GX argument enables exception handling.
For the Verilog PLI, the <init_function> should be "init_usertfs". Alternatively, if there is no init_usertfs function, the <init_function> specified on the command line should be
"veriusertfs". For the Verilog VPI, the <init_function> should be
"vlog_startup_routines". These requirements ensure that the appropriate symbol is exported, and thus ModelSim can find the symbol when it dynamically loads the DLL.
When executing cl commands in a DO file, use the /NOLOGO switch to prevent the
Microsoft C compiler from writing the logo banner to stderr. Writing the logo causes Tcl to think an error occurred.
•
MinGW C++ Version 3.2.3
g++ -c -I<install_dir>\modeltech\include app.cpp
g++ -shared -Bsymbolic -o app.dll app.o -L<install_dir>\modeltech\win32 -lmtipli
ModelSim requires the use of MinGW gcc compiler rather than the Cygwin gcc compiler.
DPI Imports on Windows Platforms
When linking the shared objects, be sure to specify one -export option for each DPI imported task or function in your linking command line. You can use Verilog’s -isymfile option to obtain a complete list of all imported tasks and functions expected by ModelSim.
DPI Special Flow for Exported Tasks and Functions
Since the Windows platform lacks the necessary runtime linking complexity, you must perform an additional manual step in order to compile the HDL source files into the shared object file.
You need to invoke a special run of vsim. The command is as follows:
vsim <top du list> -dpiexportobj <objname> <other args>
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The -dpiexportobj generates the object file <objname>.obj that contains "glue" code for exported tasks and functions. You must add that object file to the link line, listed after the other object files. For example, if the object name was dpi1, the link line for MinGW would be:
g++ -shared -Bsymbolic -o app.dll app.obj <objname>.obj
-L<install_dir>\modeltech\win32 -lmtipli
32-bit Linux Platform
•
GNU C++ Version 2.95.3 or Later
g++ -c -fPIC -I<install_dir>/modeltech/include app.cpp
g++ -shared -Bsymbolic -fPIC -o app.so app.o
64-bit Linux for IA64 Platform
64-bit Linux is supported on RedHat Linux Advanced Workstation 2.1 for Itanium 2.
•
GNU C++ compiler version gcc 3.2 or later
g++ -c -fPIC -I/<install_dir>/modeltech/include app.cpp
ld -shared -Bsymbolic -E --allow-shlib-undefined -o app.so app.o
If your PLI/VPI application requires a user or vendor-supplied C library, or an additional system library, you will need to specify that library when you link your
PLI/VPI application. For example, to use the system math library libm, specify '-lm' to the 'ld' command:
g++ -c -fPIC -I/<install_dir>/modeltech/include math_app.cpp
ld -shared -Bsymbolic -E --allow-shlib-undefined -o math_app.so math_app.o -lm
64-bit Linux for Opteron/Athlon 64 and EM64T Platforms
64-bit Linux is supported on RedHat Linux EWS 3.0 for Opteron/Athlon 64 and EM64T.
•
GNU C++ compiler version gcc 3.2 or later
g++ -c -fPIC -I/<install_dir>/modeltech/include app.cpp
ld -shared -Bsymbolic -E --allow-shlib-undefined -o app.so app.o
To compile for 32-bit operation, specify the -m32 argument on the gcc command line.
If your PLI/VPI/DPI application requires a user or vendor-supplied C library, or an additional system library, you will need to specify that library when you link your
PLI/VPI/DPI application. For example, to use the system math library libm, specify -lm to the ld command:
g++ -c -fPIC -I/<install_dir>/modeltech/include math_app.cpp
ld -shared -Bsymbolic -E --allow-shlib-undefined -o math_app.so math_app.o -lm
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32-bit Solaris Platform
If your PLI/VPI application uses anything from a system library, you will need to specify that library when you link your PLI/VPI application. For example, to use the standard C library, specify ‘-lc’ to the ‘ld’ command.
•
GNU C++ compiler version gcc 3.2 or later
g++ -c -I/<install_dir>/modeltech/include app.cpp
ld -G -Bsymbolic -o app.so app.o -lc
•
Sun Forte C++ Compiler
cc -c -I/<install_dir>/modeltech/include app.cpp
ld -G -Bsymbolic -o app.so app.o -lc
64-bit Solaris Platform
•
GNU C++ compiler version gcc 3.2 or later
g++ -c -I<install_dir>/modeltech/include -m64 -fPIC app.cpp
g++ -shared -Bsymbolic -o app.so -m64 app.o
This was tested with gcc 3.2.2. You may need to add the location of libgcc_s.so.1 to the
LD_LIBRARY_PATH_64 environment variable.
• cc compiler
cc -v -xarch=v9 -O -I<install_dir>/modeltech/include -c app.cpp
ld -G -Bsymbolic app.o -o app.so
32-bit HP700 Platform
A shared library is created by creating object files that contain position-independent code (use the +z or -fPIC compiler argument) and by linking as a shared library (use the -b linker argument).
If your PLI/VPI application uses anything from a system library, you’ll need to specify that library when you link your PLI/VPI application. For example, to use the standard C library, specify ‘-lc’ to the ‘ld’ command.
•
GNU C++ compiler
g++ -c -fPIC -I/<install_dir>/modeltech/include app.cpp
ld -b -o app.sl app.o -lc
• cc compiler
cc -c +z +DD32 -I/<install_dir>/modeltech/include app.cpp
ld -b -o app.sl app.o -lc
Note that -fPIC may not work with all versions of gcc.
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64-bit HP Platform
• cc Compiler
cc -v +DD64 -O -I<install_dir>/modeltech/include -c app.cpp
ld -b -o app.sl app.o -lc
64-bit HP for IA64 Platform
•
HP ANSI C++ Compiler (/opt/ansic/bin/cc, /usr/ccs/bin/ld)
cc -c +DD64 -I/<install_dir>/modeltech/include app.cpp
ld -b -o app.sl app.o
If your PLI/VPI application requires a user or vendor-supplied C library, or an additional system library, you will need to specify that library when you link your
PLI/VPI application. For example, to use the system math library, specify '-lm' to the 'ld' command:
cc -c +DD64 -I/<install_dir>/modeltech/include math_app.c
ld -b -o math_app.sl math_app.o -lm
32-bit IBM RS/6000 Platform
ModelSim loads shared libraries on the IBM RS/6000 workstation. The shared library must import ModelSim's PLI/VPI symbols, and it must export the PLI or VPI application’s initialization function or table. The ModelSim tool's export file is located in the ModelSim installation directory in rs6000/mti_exports.
If your PLI/VPI application uses anything from a system library, you’ll need to specify that library when you link your PLI/VPI application. For example, to use the standard C library, specify ‘-lc’ to the ‘ld’ command. The resulting object must be marked as shared reentrant using these gcc or cc compiler commands for AIX 4.x:
•
GNU C++ compiler version gcc 3.2 or later
g++ -c -I/<install_dir>/modeltech/include app.cpp
ld -o app.sl app.o -bE:app.exp \
-bI:/<install_dir>/modeltech/rs6000/mti_exports -bM:SRE -bnoentry -lc
•
VisualAge C++ Compiler
cc -c -I/<install_dir>/modeltech/include app.cpp
ld -o app.sl app.o -bE:app.exp \
-bI:/<install_dir>/modeltech/rs6000/mti_exports -bM:SRE -bnoentry -lc
The app.exp file must export the PLI/VPI initialization function or table. For the PLI, the exported symbol should be "init_usertfs". Alternatively, if there is no init_usertfs function, then the exported symbol should be "veriusertfs". For the VPI, the exported symbol should be
"vlog_startup_routines". These requirements ensure that the appropriate symbol is exported, and thus ModelSim can find the symbol when it dynamically loads the shared object.
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For DPI Imports
When linking the shared objects, be sure to specify -bE:<isymfile> option on the link command line. <isymfile> is the name of the file generated by the-isymfile argument to the vlog command. Once you have created the <isymfile>, it contains a complete list of all imported tasks and functions expected by ModelSim.
DPI Special Flow for Exported Tasks and Functions
Since the RS6000 platform lacks the necessary runtime linking capabilities, you must perform an additional manual step in order to prepare shared objects containing calls to exported
SystemVerilog tasks or functions shared object file. You need to invoke a special run of vsim .
The command is as follows:
vsim <top du list> -dpiexportobj <objname> <other args>
The -dpiexportobj generates the object file <objname>.o that contains "glue" code for exported tasks and functions. You must add that object file to the link line, listed after the other object files. For example, a link line would be:
ld -o app.dll app.o <objname>.o
-bE:<isymfile> -bI:/<install_dir>/modeltech/rs6000/mti_exports -bM:SRE
-bnoentry -lc
64-bit IBM RS/6000 Platform
Only version 5.1 and later of AIX supports the 64-bit platform. A gcc 64-bit compiler is not available at this time.
•
VisualAge C++ Compiler
cc -c -q64 -I/<install_dir>/modeltech/include app.cpp
ld -o app.s1 app.o -b64 -bE:app.exports \
-bI:/<install_dir>/modeltech/rs64/mti_exports -bM:SRE -bnoentry -lc
For DPI Imports
When linking the shared objects, be sure to specify -bE:<isymfile> option on the link command line. <isymfile> is the name of the file generated by the-isymfile argument to the vlog command. Once you have created the <isymfile>, it contains a complete list of all imported tasks and functions expected by ModelSim.
DPI Special Flow for Exported Tasks and Functions
Since the RS6000 platform lacks the necessary runtime linking capabilities, you must perform an additional manual step in order to prepare shared objects containing calls to exported
SystemVerilog tasks or functions shared object file. You need to invoke a special run of vsim .
The command is as follows:
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Specifying Application Files to Load vsim <top du list> -dpiexportobj <objname> <other args>
The -dpiexportobj generates the object file <objname>.o that contains "glue" code for exported tasks and functions. You must add that object file to the link line, listed after the other object files. For example, a link line would be:
ld -o app.so app.o <objname>.o
-bE:<isymfile> -bI:/<install_dir>/modeltech/rs6000/mti_exports -bM:SRE
-bnoentry -lc
Specifying Application Files to Load
PLI and VPI file loading is identical. DPI file loading uses switches to the vsim command.
PLI/VPI file loading
The PLI/VPI applications are specified as follows:
•
As a list in the Veriuser entry in the modelsim.ini file:
Veriuser = pliapp1.so pliapp2.so pliappn.so
•
As a list in the PLIOBJS environment variable:
% setenv PLIOBJS "pliapp1.so pliapp2.so pliappn.so"
•
As a -pli argument to the simulator (multiple arguments are allowed):
-pli pliapp1.so -pli pliapp2.so -pli pliappn.so
Note
On Windows platforms, the file names shown above should end with .dll rather than .so.
The various methods of specifying PLI/VPI applications can be used simultaneously. The libraries are loaded in the order listed above. Environment variable references can be used in the paths to the libraries in all cases.
See also
Simulator Variables for more information on the modelsim.ini file.
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PLI Example
DPI File Loading
DPI applications are specified to vsim using the following SystemVerilog arguments:
Argument
-sv_lib <name>
Table D-1. vsim Arguments for DPI Application
Description
specifies a library name to be searched and used. No filename extensions must be specified. (The extensions ModelSim expects are: .sl for HP, .dll for Win32, .so for all other platforms.)
-sv_root <name> specifies a new prefix for shared objects as specified by -sv_lib
-sv_liblist specifies a “bootstrap file” to use
When the simulator finds an imported task or function, it searches for the symbol in the collection of shared objects specified using these arguments.
For example, you can specify the DPI application as follows:
vsim -sv_lib dpiapp1 -sv_lib dpiapp2 -sv_lib dpiappn top
It is a mistake to specify DPI import tasks and functions (tf) inside PLI/VPI shared objects.
However, a DPI import tf can make calls to PLI/VPI C code, providing that vsim -gblso was used to mark the PLI/VPI shared object with global symbol visibility. See
Objects with Global Symbol Visibility
.
Loading Shared Objects with Global Symbol Visibility
On Unix platforms you can load shared objects such that all symbols in the object have global visibility. To do this, use the -gblso argument to vsim when you load your PLI/VPI application.
For example:
vsim -pli obj1.so -pli obj2.so -gblso obj1.so top
The -gblso argument works in conjunction with the GlobalSharedObjectList variable in the
modelsim.ini file. This variable allows user C code in other shared objects to refer to symbols in a shared object that has been marked as global. All shared objects marked as global are loaded by the simulator earlier than any non-global shared objects.
PLI Example
The following example is a trivial, but complete PLI application.
hello.c:
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VPI Example
#include "veriuser.h" static PLI_INT32 hello()
{ io_printf("Hi there\n"); return 0;
} s_tfcell veriusertfs[] = {
{usertask, 0, 0, 0, hello, 0, "$hello"},
{0} /* last entry must be 0 */
}; hello.v: module hello; initial $hello; endmodule
Compile the PLI code for the Solaris operating system:
% cc -c -I<install_dir>/modeltech/include hello.c
% ld -G -Bsymbolic -o hello.sl hello.o
Compile the Verilog code:
% vlib work
% vlog hello.v
Simulate the design:
% vsim -c -pli hello.sl hello
# Loading work.hello
# Loading ./hello.sl
VSIM 1> run -all
# Hi there
VSIM 2> quit
VPI Example
The following example is a trivial, but complete VPI application. A general VPI example can be found in <install_dir>/modeltech/examples/verilog/vpi.
hello.c:
#include "vpi_user.h" static PLI_INT32 hello(PLI_BYTE8 * param)
{ vpi_printf( "Hello world!\n" ); return 0;
} void RegisterMyTfs( void )
{ s_vpi_systf_data systf_data; vpiHandle systf_handle; systf_data.type = vpiSysTask; systf_data.sysfunctype = vpiSysTask; systf_data.tfname = "$hello"; systf_data.calltf = hello; systf_data.compiletf = 0; systf_data.sizetf = 0; systf_data.user_data = 0; systf_handle = vpi_register_systf( &systf_data ); vpi_free_object( systf_handle );
}
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DPI Example
void (*vlog_startup_routines[])() = {
RegisterMyTfs,
0
}; hello.v: module hello; initial $hello; endmodule
Compile the VPI code for the Solaris operating system:
% gcc -c -I<install_dir>/include hello.c
% ld -G -Bsymbolic -o hello.sl hello.o
Compile the Verilog code:
% vlib work
% vlog hello.v
Simulate the design:
% vsim -c -pli hello.sl hello
# Loading work.hello
# Loading ./hello.sl
VSIM 1> run -all
# Hello world!
VSIM 2> quit
DPI Example
The following example is a trivial but complete DPI application. For win32 and RS6000 platforms, an additional step is required. For additional examples, see the
<install_dir>/modeltech/examples/systemverilog/dpi directory.
hello_c.c:
#include "svdpi.h"
#include "dpiheader.h" int c_task(int i, int *o)
{ printf("Hello from c_task()\n"); verilog_task(i, o); /* Call back into Verilog */
*o = i; return(0); /* Return success (required by tasks) */
} hello.v: module hello_top; int ret; export "DPI-C" task verilog_task; task verilog_task(input int i, output int o);
#10;
$display("Hello from verilog_task()"); endtask import "DPI-C" context task c_task(input int i, output int o); initial begin end c_task(1, ret); // Call the c task named 'c_task()' endmodule
Compile the Verilog code:
% vlib work
% vlog -sv -dpiheader dpiheader.h hello.v
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The PLI Callback reason Argument
Compile the DPI code for the Solaris operating system:
% gcc -c -g -I<install_dir>/modeltech/include hello_c.c
% ld -G -Bsymbolic -o hello_c.so hello_c.o
Simulate the design:
% vsim -c -sv_lib hello_c hello_top
# Loading work.hello_c
# Loading ./hello_c.so
VSIM 1> run -all
# Hello from c_task()
# Hello from verilog_task()
VSIM 2> quit
The PLI Callback reason Argument
The second argument to a PLI callback function is the reason argument. The values of the various reason constants are defined in the veriuser.h include file. See IEEE Std 1364 for a description of the reason constants. The following details relate to ModelSim Verilog, and may not be obvious in the IEEE Std 1364. Specifically, the simulator passes the reason values to the misctf callback functions under the following circumstances: reason_endofcompile
For the completion of loading the design.
reason_finish
For the execution of the $finish system task or the quit command.
reason_startofsave
For the start of execution of the checkpoint command, but before any of the simulation state has been saved. This allows the PLI application to prepare for the save, but it shouldn't save its data with calls to tf_write_save() until it is called with reason_save.
reason_save
For the execution of the checkpoint command. This is when the PLI application must save its state with calls to tf_write_save().
reason_startofrestart
For the start of execution of the restore command, but before any of the simulation state has been restored. This allows the PLI application to prepare for the restore, but it shouldn't restore its state with calls to tf_read_restart() until it is called with reason_restart. The reason_startofrestart value is passed only for a restore command, and not in the case that the simulator is invoked with -restore.
reason_restart
For the execution of the restore command. This is when the PLI application must restore its state with calls to tf_read_restart().
reason_reset
For the execution of the restart command. This is when the PLI application should free its memory and reset its state. We recommend that all PLI applications reset their internal state during a restart as the shared library containing the PLI code might not be
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The sizetf Callback Function
reloaded. (See the -keeploaded and -keeploadedrestart arguments to vsim for related information.) reason_endofreset
For the completion of the restart command, after the simulation state has been reset but before the design has been reloaded.
reason_interactive
For the execution of the $stop system task or any other time the simulation is interrupted and waiting for user input.
reason_scope
For the execution of the environment command or selecting a scope in the structure window. Also for the call to acc_set_interactive_scope() if the callback_flag argument is non-zero.
reason_paramvc
For the change of value on the system task or function argument.
reason_synch
For the end of time step event scheduled by tf_synchronize().
reason_rosynch
For the end of time step event scheduled by tf_rosynchronize().
reason_reactivate
For the simulation event scheduled by tf_setdelay().
reason_paramdrc
Not supported in ModelSim Verilog.
reason_force
Not supported in ModelSim Verilog.
reason_release
Not supported in ModelSim Verilog.
reason_disable
Not supported in ModelSim Verilog.
The sizetf Callback Function
A user-defined system function specifies the width of its return value with the sizetf callback function, and the simulator calls this function while loading the design. The following details on the sizetf callback function are not found in the IEEE Std 1364:
•
If you omit the sizetf function, then a return width of 32 is assumed.
•
The sizetf function should return 0 if the system function return value is of Verilog type
"real".
•
The sizetf function should return -32 if the system function return value is of Verilog type "integer".
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PLI Object Handles
PLI Object Handles
Many of the object handles returned by the PLI ACC routines are pointers to objects that naturally exist in the simulation data structures, and the handles to these objects are valid throughout the simulation, even after the acc_close() routine is called. However, some of the objects are created on demand, and the handles to these objects become invalid after acc_close() is called. The following object types are created on demand in ModelSim Verilog:
accOperator (acc_handle_condition) accWirePath (acc_handle_path) accTerminal (acc_handle_terminal, acc_next_cell_load, acc_next_driver, and acc_next_load) accPathTerminal (acc_next_input and acc_next_output) accTchkTerminal (acc_handle_tchkarg1 and acc_handle_tchkarg2) accPartSelect (acc_handle_conn, acc_handle_pathin, and acc_handle_pathout)
If your PLI application uses these types of objects, then it is important to call acc_close() to free the memory allocated for these objects when the application is done using them.
If your PLI application places value change callbacks on accRegBit or accTerminal objects, do
not call acc_close() while these callbacks are in effect.
Third Party PLI Applications
Many third party PLI applications come with instructions on using them with ModelSim
Verilog. Even without the instructions, it is still likely that you can get it to work with
ModelSim Verilog as long as the application uses standard PLI routines. The following guidelines are for preparing a Verilog-XL PLI application to work with ModelSim Verilog.
Generally, a Verilog-XL PLI application comes with a collection of object files and a veriuser.c
file. The veriuser.c file contains the registration information as described above in
PLI Applications . To prepare the application for ModelSim Verilog, you must compile the
veriuser.c file and link it to the object files to create a dynamically loadable object (see
Compiling and Linking C Applications for PLI/VPI/DPI
). For example, if you have a veriuser.c file and a library archive libapp.a file that contains the application's object files, then the following commands should be used to create a dynamically loadable object for the Solaris operating system:
% cc -c -I<install_dir>/modeltech/include veriuser.c
% ld -G -o app.sl veriuser.o libapp.a
The PLI application is now ready to be run with ModelSim Verilog. All that's left is to specify the resulting object file to the simulator for loading using the Veriuser entry in the modesim.ini file, the -pli simulator argument, or the PLIOBJS environment variable (see
).
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Support for VHDL Objects
Note
On the HP700 platform, the object files must be compiled as position-independent code by using the +z compiler argument. Since, the object files supplied for Verilog-XL may be compiled for static linking, you may not be able to use the object files to create a dynamically loadable object for ModelSim Verilog. In this case, you must get the third party application vendor to supply the object files compiled as position-independent code.
Support for VHDL Objects
The PLI ACC routines also provide limited support for VHDL objects in either an all VHDL design or a mixed VHDL/Verilog design. The following table lists the VHDL objects for which handles may be obtained and their type and fulltype constants:
Type
accArchitecture accArchitecture accArchitecture accArchitecture accArchitecture accArchitecture accBlock accForLoop accForeign accGenerate accPackage accSignal
Table D-2. Supported VHDL Objects
Fulltype Description
accArchitecture instantiation of an architecture accEntityVitalLevel0 instantiation of an architecture whose entity is marked with the attribute VITAL_Level0 accArchVitalLevel0 instantiation of an architecture which is marked with the attribute VITAL_Level0 accArchVitalLevel1 instantiation of an architecture which is marked with the attribute VITAL_Level1 accForeignArch instantiation of an architecture which is marked with the attribute FOREIGN and which does not contain any VHDL statements or objects other than ports and generics accForeignArchMixed instantiation of an architecture which is marked with the attribute FOREIGN and which contains some VHDL statements or objects besides ports and generics accBlock accForLoop block statement for loop statement accShadow accGenerate accPackage accSignal foreign scope created by mti_CreateRegion() generate statement package declaration signal declaration
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Support for VHDL Objects
The type and fulltype constants for VHDL objects are defined in the acc_vhdl.h include file. All of these objects (except signals) are scope objects that define levels of hierarchy in the structure window. Currently, the PLI ACC interface has no provision for obtaining handles to generics, types, constants, variables, attributes, subprograms, and processes.
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IEEE Std 1364 ACC Routines
IEEE Std 1364 ACC Routines
ModelSim Verilog supports the following ACC routines:
Table D-3. Supported ACC Routines
Routines
acc_append_delays acc_append_pulsere acc_close acc_collect acc_compare_handles acc_configure acc_count acc_fetch_argc acc_fetch_argv acc_fetch_attribute acc_fetch_attribute_int acc_fetch_attribute_str acc_fetch_defname acc_fetch_delay_mode acc_fetch_delays acc_fetch_direction acc_fetch_edge acc_fetch_fullname acc_fetch_fulltype acc_fetch_index acc_fetch_location acc_fetch_name acc_fetch_paramtype acc_fetch_paramval acc_fetch_polarity acc_fetch_precision acc_fetch_pulsere acc_fetch_range acc_fetch_size acc_fetch_tfarg acc_fetch_itfarg acc_fetch_tfarg_int acc_fetch_itfarg_int acc_fetch_tfarg_str acc_fetch_itfarg_str acc_fetch_timescale_info acc_fetch_type acc_fetch_type_str acc_fetch_value acc_free acc_handle_by_name acc_handle_calling_mod_m acc_handle_condition acc_handle_conn acc_handle_hiconn acc_handle_interactive_scope acc_handle_loconn acc_handle_modpath acc_handle_notifier acc_handle_object acc_handle_parent acc_handle_path acc_handle_pathin acc_handle_pathout acc_handle_port acc_handle_scope acc_handle_simulated_net acc_handle_tchk acc_handle_tchkarg1 acc_handle_tchkarg2 acc_handle_terminal acc_handle_tfarg acc_handle_itfarg acc_handle_tfinst acc_initialize acc_next acc_next_bit acc_next_cell acc_next_cell_load acc_next_child acc_next_driver acc_next_hiconn acc_next_input acc_next_load acc_next_loconn acc_next_modpath acc_next_net acc_next_output acc_next_parameter acc_next_port acc_next_portout acc_next_primitive acc_next_scope acc_next_specparam acc_next_tchk acc_next_terminal acc_next_topmod acc_object_in_typelist acc_object_of_type acc_product_type acc_product_version acc_release_object acc_replace_delays acc_replace_pulsere acc_reset_buffer acc_set_interactive_scope acc_set_pulsere acc_set_scope acc_set_value acc_vcl_add acc_vcl_delete acc_version
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IEEE Std 1364 ACC Routines
acc_fetch_paramval() cannot be used on 64-bit platforms to fetch a string value of a parameter.
Because of this, the function acc_fetch_paramval_str() has been added to the PLI for this use.
acc_fetch_paramval_str() is declared in acc_user.h. It functions in a manner similar to acc_fetch_paramval() except that it returns a char *. acc_fetch_paramval_str() can be used on all platforms.
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IEEE Std 1364 TF Routines
IEEE Std 1364 TF Routines
ModelSim Verilog supports the following TF (task and function) routines;
Table D-4. Supported TF Routines
Routines
io_mcdprintf io_printf mc_scan_plusargs tf_add_long tf_asynchoff tf_iasynchoff tf_asynchon tf_iasynchon tf_clearalldelays tf_iclearalldelays tf_compare_long tf_copypvc_flag tf_icopypvc_flag tf_divide_long tf_dofinish tf_dostop tf_error tf_evaluatep tf_ievaluatep tf_exprinfo tf_iexprinfo tf_getcstringp tf_igetcstringp tf_getinstance tf_getlongp tf_igetlongp tf_getlongtime tf_igetlongtime tf_getnextlongtime tf_getp tf_igetp tf_getpchange tf_igetpchange tf_getrealp tf_igetrealp tf_getrealtime tf_igetrealtime tf_gettime tf_igettime tf_gettimeprecision tf_igettimeprecision tf_gettimeunit tf_igettimeunit tf_getworkarea tf_igetworkarea tf_long_to_real tf_longtime_tostr tf_message tf_mipname tf_imipname tf_movepvc_flag tf_imovepvc_flag tf_multiply_long tf_nodeinfo tf_inodeinfo tf_nump tf_inump tf_propagatep tf_ipropagatep tf_putlongp tf_iputlongp tf_putp tf_iputp tf_putrealp tf_iputrealp tf_read_restart tf_real_to_long tf_rosynchronize tf_irosynchronize tf_scale_longdelay tf_scale_realdelay tf_setdelay tf_isetdelay tf_setlongdelay tf_isetlongdelay tf_setrealdelay tf_isetrealdelay tf_setworkarea tf_isetworkarea tf_sizep tf_isizep tf_spname tf_ispname tf_strdelputp tf_istrdelputp tf_strgetp tf_istrgetp tf_strgettime tf_strlongdelputp tf_istrlongdelputp tf_strrealdelputp tf_istrrealdelputp tf_subtract_long tf_synchronize tf_isynchronize tf_testpvc_flag tf_itestpvc_flag tf_text tf_typep tf_itypep tf_unscale_longdelay tf_unscale_realdelay tf_warning tf_write_save
SystemVerilog DPI Access Routines
ModelSim SystemVerilog supports all routines defined in the "svdpi.h" file defined in P1800-
2005.
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Verilog-XL Compatible Routines
Verilog-XL Compatible Routines
The following PLI routines are not defined in IEEE Std 1364, but ModelSim Verilog provides them for compatibility with Verilog-XL.
char *acc_decompile_exp(handle condition)
This routine provides similar functionality to the Verilog-XL acc_decompile_expr routine. The condition argument must be a handle obtained from the acc_handle_condition routine. The value returned by acc_decompile_exp is the string representation of the condition expression.
char *tf_dumpfilename(void)
This routine returns the name of the VCD file.
void tf_dumpflush(void)
A call to this routine flushes the VCD file buffer (same effect as calling $dumpflush in the
Verilog code).
int tf_getlongsimtime(int *aof_hightime)
This routine gets the current simulation time as a 64-bit integer. The low-order bits are returned by the routine, while the high-order bits are stored in the aof_hightime argument.
64-bit Support for PLI
The PLI function acc_fetch_paramval() cannot be used on 64-bit platforms to fetch a string value of a parameter. Because of this, the function acc_fetch_paramval_str() has been added to the PLI for this use. acc_fetch_paramval_str() is declared in acc_user.h. It functions in a manner similar to acc_fetch_paramval() except that it returns a char *. acc_fetch_paramval_str() can be used on all platforms.
Using 64-bit ModelSim with 32-bit Applications
If you have 32-bit PLI/VPI/DPI applications and wish to use 64-bit ModelSim, you will need to port your code to 64 bits by moving from the ILP32 data model to the LP64 data model. We strongly recommend that you consult the 64-bit porting guides for Sun and HP.
PLI/VPI Tracing
The foreign interface tracing feature is available for tracing PLI and VPI function calls. Foreign interface tracing creates two kinds of traces: a human-readable log of what functions were called, the value of the arguments, and the results returned; and a set of C-language files that can be used to replay what the foreign interface code did.
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PLI/VPI Tracing
The Purpose of Tracing Files
The purpose of the logfile is to aid you in debugging PLI or VPI code. The primary purpose of the replay facility is to send the replay files to support for debugging co-simulation problems, or debugging PLI/VPI problems for which it is impractical to send the PLI/VPI code. We still need you to send the VHDL/Verilog part of the design to actually execute a replay, but many problems can be resolved with the trace only.
Invoking a Trace
To invoke the trace, call vsim with the -trace_foreign argument:
Syntax
vsim
-trace_foreign <action> [-tag <name>]
Arguments
<action>
Can be either the value 1, 2, or 3. Specifies one of the following actions:
Value
1
2
3
Table D-5. Values for <action> Argument
Operation Result
create log only create replay only create both log and replay writes a local file called
"mti_trace_<tag>" writes local files called
"mti_data_<tag>.c",
"mti_init_<tag>.c",
"mti_replay_<tag>.c" and
"mti_top_<tag>.c" writes all above files
-tag <name>
Used to give distinct file names for multiple traces. Optional.
Examples
vsim -trace_foreign 1 mydesign
Creates a logfile.
vsim -trace_foreign 3 mydesign
Creates both a logfile and a set of replay files.
vsim -trace_foreign 1 -tag 2 mydesign
Creates a logfile with a tag of "2".
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Debugging PLI/VPI/DPI Application Code
The tracing operations will provide tracing during all user foreign code-calls, including PLI/VPI user tasks and functions (calltf, checktf, sizetf and misctf routines), and Verilog VCL callbacks.
Debugging PLI/VPI/DPI Application Code
In order to debug your PLI/VPI/DPI application code in a debugger, you must first:
1. Compile the application code with debugging information (using the -g option) and without optimizations (for example, don’t use the -O option).
2. Load vsim into a debugger.
Even though vsim is stripped, most debuggers will still execute it. You can invoke the debugger directly on vsimk, the simulation kernel where your application code is loaded
(for example, "ddd `which vsimk`"), or you can attach the debugger to an already running vsim process. In the second case, you must attach to the PID for vsimk, and you must specify the full path to the vsimk executable (for example, "gdb
$MTI_HOME/sunos5/vsimk 1234").
On Solaris, AIX, and Linux systems you can use either gdb or ddd. On HP-UX systems you can use the wdb debugger from HP. You will need version 1.2 or later.
3. Set an entry point using breakpoint.
Since initially the debugger recognizes only vsim's PLI/VPI/DPI function symbols, when invoking the debugger directly on vsim you need to place a breakpoint in the first
PLI/VPI/DPI function that is called by your application code. An easy way to set an entry point is to put a call to acc_product_version() as the first executable statement in your application code. Then, after vsim has been loaded into the debugger, set a breakpoint in this function. Once you have set the breakpoint, run vsim with the usual arguments.
When the breakpoint is reached, the shared library containing your application code has been loaded.
4. In some debuggers, you must use the share command to load the application's symbols.
At this point all of the application's symbols should be visible. You can now set breakpoints in and single step through your application code.
Troubleshooting a Missing DPI Import Function
DPI uses C function linkage. If your DPI application is written in C++, it is important to remember to use extern "C" declaration syntax appropriately. Otherwise the C++ compiler will produce a mangled C++ name for the function, and the simulator is not able to locate and bind the DPI call to that function.
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Debugging PLI/VPI/DPI Application Code
Also, if you do not use the -Bsymbolic argument on the command line for specifying a link, the system may bind to an incorrect function, resulting in unexpected behavior. For more information, see
Correct Linking of Shared Libraries with -Bsymbolic .
HP-UX Specific Warnings
On HP-UX you might see some warning messages that vsim does not have debugging information available. This is normal. If you are using Exceed to access an HP machine from
Windows NT, it is recommended that you run vsim in command line or batch mode because your NT machine may hang if you run vsim in GUI mode. Click on the "go" button, or use F5 or the go command to execute vsim in wdb.
You might also see a warning about not finding "__dld_flags" in the object file. This warning can be ignored. You should see a list of libraries loaded into the debugger. It should include the library for your PLI/VPI/DPI application. Alternatively, you can use share to load only a single library.
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Appendix E
Command and Keyboard Shortcuts
This appendix is a collection of the keyboard and command shortcuts available in the
ModelSim GUI.
Command Shortcuts
•
You may abbreviate command syntax, but there’s a catch — the minimum number of characters required to execute a command are those that make it unique. Remember, as we add new commands some of the old shortcuts may not work. For this reason
ModelSim does not allow command name abbreviations in macro files. This minimizes your need to update macro files as new commands are added.
•
Multiple commands may be entered on one line if they are separated by semi-colons (;).
For example:
vlog -nodebug=ports level3.v level2.v ; vlog -nodebug top.v
The return value of the last function executed is the only one printed to the transcript.
This may cause some unexpected behavior in certain circumstances. Consider this example:
vsim -c -do "run 20 ; simstats ; quit -f" top
You probably expect the simstats results to display in the Transcript window, but they will not, because the last command is quit -f. To see the return values of intermediate commands, you must explicitly print the results. For example:
vsim -do "run 20 ; echo [simstats]; quit -f" -c top
Command History Shortcuts
You can review the simulator command history, or reuse previously entered commands with the following shortcuts at the ModelSim/VSIM prompt:
Shortcut
!!
!n
!abc
Table E-1. Command History Shortcuts
Description
repeats the last command repeats command number n; n is the VSIM prompt number (e.g., for this prompt: VSIM 12>, n =12) repeats the most recent command starting with "abc"
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Main and Source Window Mouse and Keyboard Shortcuts
Shortcut
^xyz^ab^ up arrow and down arrow keys
Table E-1. Command History Shortcuts (cont.)
Description
replaces "xyz" in the last command with "ab" scrolls through the command history click on prompt his or history left-click once on a previous ModelSim or VSIM prompt in the transcript to copy the command typed at that prompt to the active cursor shows the last few commands (up to 50 are kept)
Main and Source Window Mouse and Keyboard
Shortcuts
The following mouse actions and special keystrokes can be used to edit commands in the entry region of the Main window. They can also be used in editing the file displayed in the Source window and all Notepad windows (enter the notepad command within ModelSim to open the
Notepad editor).
Mouse - UNIX and Windows
Table E-2. Mouse Shortcuts
Result
Click the left mouse button
Click and drag the left mouse button relocate the cursor select an area
Shift-click the left mouse button
Double-click the left mouse button
Double-click and drag the left mouse button
Ctrl-click the left mouse button extend selection select a word select a group of words move insertion cursor without changing the selection
Click the left mouse button on a previous
ModelSim or VSIM prompt
Click the middle mouse button
Click and drag the middle mouse button copy and paste previous command string to current prompt paste selection to the clipboard scroll the window
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Table E-3. Keyboard Shortcuts
Keystrokes - UNIX and Windows Result
Left Arrow
Right Arrow move cursor left or right one character
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Command and Keyboard Shortcuts
Main and Source Window Mouse and Keyboard Shortcuts
Ctrl + Left Arrow
Ctrl + Right Arrow
Table E-3. Keyboard Shortcuts (cont.)
Keystrokes - UNIX and Windows Result
move cursor left or right one word
Shift + Any Arrow
Ctrl + Shift + Left Arrow
Ctrl + Shift + Right Arrow extend text selection extend text selection by one word
Up Arrow
Down Arrow
Ctrl + Up Arrow
Ctrl + Down Arrow
Ctrl + Home
Ctrl + End
Backspace
Ctrl + h (UNIX only)
Delete
Ctrl + d (UNIX only)
Transcript Pane: scroll through command history
Source Window: move cursor one line up or down
Transcript Pane: moves cursor to first or last line
Source Window: moves cursor up or down one paragraph move cursor to the beginning of the text move cursor to the end of the text delete character to the left delete character to the right
Esc (Windows only)
Alt
Alt-F4
Home
Ctrl + a (UNIX only)
Ctrl + b
Ctrl + d
End
Ctrl + e
Ctrl + f (UNIX)
Right Arrow (Windows)
Ctrl + k
Ctrl + n
Ctrl + o (UNIX only)
Ctrl + p cancel activate or inactivate menu bar mode close active window move cursor to the beginning of the line move cursor left delete character to the right move cursor to the end of the line move cursor right one character delete to the end of line move cursor one line down (Source window only under Windows) insert a new line character at the cursor move cursor one line up (Source window only under
Windows)
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Main and Source Window Mouse and Keyboard Shortcuts
Ctrl + s (UNIX)
Ctrl + f (Windows)
Table E-3. Keyboard Shortcuts (cont.)
Keystrokes - UNIX and Windows Result
find
Ctrl + t
Ctrl + u
Page Down
Ctrl + v (UNIX only)
Ctrl + w (UNIX)
Ctrl + x (Windows) reverse the order of the two characters on either side of the cursor delete line move cursor down one screen cut the selection save Ctrl + s
Ctrl + x (UNIX Only)
Ctrl + y (UNIX)
Ctrl + v (Windows)
Ctrl + a (Windows Only)
Ctrl + \
Ctrl + - (UNIX)
Ctrl + / (UNIX)
Ctrl + z (Windows) paste the selection select the entire contents of the widget clear any selection in the widget undoes previous edits in the Source window move cursor to the beginning of the file move cursor to the end of the file move cursor up one screen
Meta + < (UNIX only)
Meta + > (UNIX only)
Page Up
Meta + v (UNIX only)
Meta + w (UNIX)
Ctrl + c (Windows)
F3
F4
Shift+F4
F5
Shift+F5
F8
F9
F10
F11 (Windows only) copy selection
Peforms a Find Next action in the Source Window.
Change focus to next pane in main window
Change focus to previous pane in main window
Toggle between expanding and restoring size of pane to fit the entire main window
Toggle on/off the pane headers.
search for the most recent command that matches the characters typed (Main window only) run simulation continue simulation single-step
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Command and Keyboard Shortcuts
List Window Keyboard Shortcuts
Table E-3. Keyboard Shortcuts (cont.)
Keystrokes - UNIX and Windows Result
F12 (Windows only) step-over
The Main window allows insertions or pastes only after the prompt; therefore, you don’t need to set the cursor when copying strings to the command line.
List Window Keyboard Shortcuts
Using the following keys when the mouse cursor is within the List window will cause the indicated actions:
Table E-4. List Window Keyboard Shortcuts
Key - UNIX and Windows Action
Left Arrow
Right Arrow scroll listing left (selects and highlights the item to the left of the currently selected item) scroll listing right (selects and highlights the item to the right of the currently selected item)
Up Arrow
Down Arrow
Page Up
Ctrl + Up Arrow
Page Down
Ctrl + Down Arrow
Tab scroll listing up scroll listing down scroll listing up by page scroll listing down by page
Shift + Tab searches forward (down) to the next transition on the selected signal searches backward (up) to the previous transition on the selected signal (does not function on HP workstations) extends selection left/right Shift + Left Arrow
Shift + Right Arrow
Ctrl + f (Windows)
Ctrl + s (UNIX) opens the Find dialog box to find the specified item label within the list display
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Wave Window Mouse and Keyboard Shortcuts
Wave Window Mouse and Keyboard Shortcuts
The following mouse actions and keystrokes can be used in the Wave window.
Table E-5. Wave Window Mouse Shortcuts
Mouse action Result
Ctrl + Click left mouse button and drag
1 zoom area (in)
Ctrl + Click left mouse button and drag
Ctrl + Click left mouse button and drag zoom out zoom fit
Click left mouse button and drag
Ctrl + Click left mouse button on a scroll bar arrow
Click middle mouse button in scroll bar
(UNIX only) moves closest cursor scrolls window to very top or bottom (vertical scroll) or far left or right (horizontal scroll) scrolls window to position of click
1. If you enter zoom mode by selecting View > Zoom > Mouse Mode > Zoom
Mode, you do not need to hold down the <Ctrl> key.
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Keystroke
s i
Shift + i
+ o
-
Shift + o f
Shift + f l
Shift + l r
Shift + r
Table E-6. Wave Window Keyboard Shortcuts
Action
bring into view and center the currently active cursor zoom in
(mouse pointer must be over the cursor or waveform panes) zoom out
(mouse pointer must be over the cursor or waveform panes) zoom full
(mouse pointer must be over the cursor or waveform panes) zoom last
(mouse pointer must be over the cursor or waveform panes) zoom range
(mouse pointer must be over the cursor or waveform panes)
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Command and Keyboard Shortcuts
Wave Window Mouse and Keyboard Shortcuts
Keystroke
Up Arrow
Down Arrow
Table E-6. Wave Window Keyboard Shortcuts
Action
scrolls entire window up or down one line, when mouse pointer is over waveform pane scrolls highlight up or down one line, when mouse pointer is over pathname or values pane
Left Arrow
Right Arrow
Page Up
Page Down
Tab scroll pathname, values, or waveform pane left scroll pathname, values, or waveform pane right scroll waveform pane up by a page scroll waveform pane down by a page
Shift + Tab
Ctrl + f (Windows)
Ctrl + s (UNIX)
Ctrl + Left Arrow
Ctrl + Right Arrow search forward (right) to the next transition on the selected signal - finds the next edge search backward (left) to the previous transition on the selected signal - finds the previous edge open the find dialog box; searches within the specified field in the pathname pane for text strings scroll pathname, values, or waveform pane left or right by a page
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Wave Window Mouse and Keyboard Shortcuts
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Appendix F
Setting GUI Preferences
The ModelSim GUI is programmed using Tcl/Tk. It is highly customizable. You can control everything from window size, position, and color to the text of window prompts, default output filenames, and so forth.
Most user GUI preferences are stored as Tcl variables in the .modelsim file on Unix/Linux platforms or the Registry on Windows platforms. The variable values save automatically when you exit ModelSim. Some of the variables are modified by actions you take with menus or windows (e.g., resizing a window changes its geometry variable). Or, you can edit the variables directly either from the ModelSim > prompt or the Edit Preferences dialog.
Customizing the Simulator GUI Layout
You can customize the layout of panes, windows, toolbars, etc. This section discusses layouts and how they are used in ModelSim.
Layouts and Modes of Operation
ModelSim ships with three default layouts that correspond to three modes of operation.
Layout
NoDesign
Simulate
Coverage
Table F-1. Predefined GUI Layouts
Mode
a design is not yet loaded a design is loaded a design is loaded with code coverage enabled
As you load and unload designs, ModelSim switches between the layouts.
Custom Layouts
You can create custom layouts or modify the three default layouts.
Creating Custom Layouts
To create a custom layout or modify one of the default layouts, follow these steps:
1. Rearrange the GUI as you see fit (see
Navigating the Graphic User Interface
for details).
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Setting GUI Preferences
Customizing the Simulator GUI Layout
2. Select Layout > Save.
Figure F-1. Save Current Window Layout Dialog Box
3. Specify a new name or use an existing name to overwrite that layout.
4. Click OK.
The layout is saved to the .modelsim file (or Registry on Windows).
Assigning Layouts to Modes
You can assign which layout appears in each mode (no design loaded, design loaded, design loaded with coverage). Follow these steps:
1. Create your custom layouts as described above.
2. Select Layout > Configure.
Example F-1. Configure Window Layouts Dialog Box
3. Select a layout for each mode.
4. Click OK.
The layout assignment is saved to the .modelsim file (Registry on Windows).
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Setting GUI Preferences
Navigating the Graphic User Interface
Automatic Saving of Layouts
By default any changes you make to a layout are saved automatically when you exit the tool or when you change modes. For example, if you load a design with code coverage, rearrange some windows, and then quit the simulation, the changes are saved to whatever layout was assigned to the "load with coverage" mode.
To disable automatic saving of layouts, select Layout > Configure and uncheck Save Window
Layout Automatically.
Resetting Layouts to Their Defaults
You can reset the layouts for the three modes to their original defaults. Select Layout > Reset.
This command does not delete custom layouts.
Navigating the Graphic User Interface
This section discusses how to rearrange various elements of the GUI.
Manipulating Panes
Window panes (e.g., Workspace) can be positioned at various places within the parent window or they can be dragged out ("undocked") of the parent window altogether.
Figure F-2. GUI: Window Pane
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Setting GUI Preferences
Navigating the Graphic User Interface
Moving Panes
When you see a double bar at the top edge of a pane, it means you can modify the pane position.
Figure F-3. GUI: Double Bar
Click-and drag the pane handle in the middle of a double bar (your mouse pointer will change to a four-headed arrow when it is in the correct location) to reposition the pane inside the parent window. As you move the mouse to various parts of the main window, a gray outline will show you valid locations to drop the pane.
Or, drag the pane outside of the parent window, and when you let go of the mouse button, the pane becomes a free-floating window.
Docking and Undocking Panes
You can undock a pane by clicking the undock button in the heading of a pane.
Figure F-4. GUI: Undock Button
To redock a floating pane, click on the pane handle at the top of the window and drag it back into the parent window, or click the dock icon.
Figure F-5. GUI: Dock Button
Zooming Panes
You can expand panes to fill the entire Main window by clicking the zoom icon in the heading of the pane.
Figure F-6. GUI: Zoom Button
To restore the pane to its original size and position click the unzoom button in the heading of the pane.
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Figure F-7. GUI: Zoom Button
Setting GUI Preferences
Simulator GUI Preferences
Columnar Information Display
Many panes (e.g., Objects, Workspace, etc.) display information in a columnar format. You can perform a number of operations on columnar formats:
•
Click and drag on a column heading to rearrange columns
•
Click and drag on a border between column names to increase/decrease column size
•
Sort columns by clicking once on the column heading to sort in ascending order; clicking twice to sort in descending order; and clicking three times to sort in default order.
•
Hide or show columns by either right-clicking a column heading and selecting an object from the context menu or by clicking the column-list drop down arrow and selecting an object.
Quick Access Toolbars
Toolbar buttons provide access to commonly used commands and functions. Toolbars can be docked and undocked (moved to or from the main toolbar area) by clicking and dragging on the toolbar handle at the left-edge of a toolbar.
Figure F-8. Toolbar Manipulation
You can also hide/show the various toolbars. To hide or show a toolbar, right-click on a blank spot of the main toolbar area and select a toolbar from the list.
To reset toolbars to their original state, right-click on a blank spot of the main toolbar area and select Reset.
Simulator GUI Preferences
Simulator GUI preferences are stored by default either in the .modelsim file in your HOME directory on UNIX/Linux platforms or the Registry on Windows platforms.
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Simulator GUI Preferences
Setting Preference Variables from the GUI
To edit a variable value from the GUI, select Tools > Edit Preferences.
The dialog organizes preferences by window and by name. The By Window tab primarily allows you to change colors and fonts for various GUI objects. For example, if you want to change the color of assertion messages in the Main window, you would select "Main window" in the first column, select "assertColor" in the second column, and click a color on the palette.
Clicking OK or Apply changes the variable, and the change is saved when you exit ModelSim.
Figure F-9. Preferences Dialog Box: By Window Tab
The By Name tab lists every Tcl variable in a tree structure. Expand the tree, highlight a variable, and click Change Value to edit the current value.
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Setting GUI Preferences
Simulator GUI Preferences
Figure F-10. Preferences Dialog Box: By Name Tab
Saving GUI Preferences
GUI preferences are saved automatically when you exit the tool.
If you prefer to store GUI preferences elsewhere, set the
environment variable to designate where these preferences are stored. Setting this variable causes ModelSim to use a specified path and file instead of the default location. Here are some additional points to keep in mind about this variable setting:
•
The file does not need to exist before setting the variable as ModelSim will initialize it.
•
If the file is read-only, ModelSim will not update or otherwise modify the file.
•
This variable may contain a relative pathname, in which case the file is relative to the working directory at the time the tool is started.
The modelsim.tcl File
Previous versions saved user GUI preferences into a modelsim.tcl file. Current versions will still read in a modelsim.tcl file if it exists. ModelSim searches for the file as follows:
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Setting GUI Preferences
Simulator GUI Preferences
• use
MODELSIM_TCL environment variable if it exists (if MODELSIM_TCL is a list
of files, each file is loaded in the order that it appears in the list); else
• use ./modelsim.tcl; else
• use $(HOME)/modelsim.tcl if it exists
Note that in versions 6.1 and later, ModelSim will save to the .modelsim file any variables it reads in from a modelsim.tcl file. The values from the modelsim.tcl file will override like variables in the .modelsim file.
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Appendix G
System Initialization
ModelSim goes through numerous steps as it initializes the system during startup. It accesses various files and environment variables to determine library mappings, configure the GUI, check licensing, and so forth.
Files Accessed During Startup
The table below describes the files that are read during startup. They are listed in the order in which they are accessed.
File
modelsim.ini
location map file
pref.tcl
Table G-1. Files Accessed During Startup
Purpose
contains initial tool settings; see
Variables for specific details on the modelsim.ini file
used by ModelSim tools to find source files based on easily reallocated "soft" paths; default file name is mgc_location_map contains defaults for fonts, colors, prompts, window positions, and other simulator window characteristics
.modelsim (UNIX) or
Windows registry
modelsim.tcl
<project_name>.mpf
contains last working directory, project file, printer defaults, and other user-customized GUI characteristics contains user-customized settings for fonts, colors, prompts, other GUI characteristics; maintained for backwards compatibility with older versions (see
if available, loads last project file which is specified in the registry (Windows) or $(HOME)/.modelsim
(UNIX); see
settings
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Environment Variables Accessed During Startup
Environment Variables Accessed During Startup
The table below describes the environment variables that are read during startup. They are listed in the order in which they are accessed. For more information on environment variables, see
Table G-2. Environment Variables Accessed During Startup
Environment variable Purpose
MODEL_TECH set by ModelSim to the directory in which the binary executables reside (e.g., ../modeltech/<platform>/)
MODEL_TECH_OVERRIDE provides an alternative directory for the binary executables;
MODEL_TECH is set to this path
MODELSIM
MGC_WD
MGC_LOCATION_MAP identifies the pathname of the modelsim.ini file identifies the Mentor Graphics working directory
MODEL_TECH_TCL identifies the pathname of the location map file; set by
ModelSim if not defined identifies the pathname of all Tcl libraries installed with
ModelSim
HOME
MGC_HOME
TCL_LIBRARY
TK_LIBRARY identifies your login directory (UNIX only) identifies the pathname of the MGC tool suite identifies the pathname of the Tcl library; set by ModelSim to the same pathname as MODEL_TECH_TCL; must point to libraries supplied by Model Technology identifies the pathname of the Tk library; set by ModelSim to the same pathname as MODEL_TECH_TCL; must point to libraries supplied by Model Technology
ITCL_LIBRARY
ITK_LIBRARY
VSIM_LIBRARY
MTI_COSIM_TRACE
MTI_LIB_DIR identifies the pathname of the [incr]Tcl library; set by
ModelSim to the same path as MODEL_TECH_TCL; must point to libraries supplied by Model Technology identifies the pathname of the [incr]Tk library; set by
ModelSim to the same pathname as MODEL_TECH_TCL; must point to libraries supplied by Model Technology identifies the pathname of the Tcl files that are used by
ModelSim; set by ModelSim to the same pathname as
MODEL_TECH_TCL; must point to libraries supplied by
Model Technology creates an mti_trace_cosim file containing debugging information about FLI/PLI/VPI function calls; set to any value before invoking the simulator identifies the path to all Tcl libraries installed with ModelSim
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Table G-2. Environment Variables Accessed During Startup
Environment variable
MTI_VCO_MODE
Purpose
determines which version of ModelSim to use on platforms that support both 32- and 64-bit versions when ModelSim executables are invoked from the modeltech/bin directory by a Unix shell command (using full path specification or PATH search)
MODELSIM_TCL identifies the pathname to a user preference file (e.g.,
C:\modeltech\modelsim.tcl); can be a list of file pathnames, separated by semicolons (Windows) or colons (UNIX); note that user preferences are now stored in the .modelsim file
(Unix) or registry (Windows); ModelSim will still read this environment variable but it will then save all the settings to the .modelsim file when you exit the tool
Initialization Sequence
The following list describes in detail ModelSim’s initialization sequence. The sequence includes a number of conditional structures, the results of which are determined by the existence of certain files and the current settings of environment variables.
In the steps below, names in uppercase denote environment variables (except MTI_LIB_DIR which is a Tcl variable). Instances of $(NAME) denote paths that are determined by an environment variable (except $(MTI_LIB_DIR) which is determined by a Tcl variable).
1. Determines the path to the executable directory (../modeltech/<platform>). Sets
MODEL_TECH to this path, unless MODEL_TECH_OVERRIDE exists, in which case
MODEL_TECH is set to the same value as MODEL_TECH_OVERRIDE.
2. Finds the modelsim.ini file by evaluating the following conditions:
• use $(MODELSIM)/modelsim.ini if it exists; else
• use $(MGC_PWD)/modelsim.ini; else
• use ./modelsim.ini; else
• use $(MODEL_TECH)/modelsim.ini; else
• use $(MODEL_TECH)/../modelsim.ini; else
• use $(MGC_HOME)/lib/modelsim.ini; else
• set path to ./modelsim.ini even though the file doesn’t exist
3. Finds the location map file by evaluating the following conditions:
• use MGC_LOCATION_MAP if it exists (if this variable is set to "no_map",
ModelSim skips initialization of the location map); else
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Initialization Sequence
• use mgc_location_map if it exists; else
• use $(HOME)/mgc/mgc_location_map; else
• use $(HOME)/mgc_location_map; else
• use $(MGC_HOME)/etc/mgc_location_map; else
• use $(MGC_HOME)/shared/etc/mgc_location_map; else
• use $(MODEL_TECH)/mgc_location_map; else
• use $(MODEL_TECH)/../mgc_location_map; else
• use no map
4. Reads various variables from the [vsim] section of the modelsim.ini file. See
Control Variables for more details.
5. Parses any command line arguments that were included when you started ModelSim and reports any problems.
6. Defines the following environment variables:
• use MODEL_TECH_TCL if it exists; else
• set MODEL_TECH_TCL=$(MODEL_TECH)/../tcl
• set TCL_LIBRARY=$(MODEL_TECH_TCL)/tcl8.3
• set TK_LIBRARY=$(MODEL_TECH_TCL)/tk8.3
• set ITCL_LIBRARY=$(MODEL_TECH_TCL)/itcl3.0
• set ITK_LIBRARY=$(MODEL_TECH_TCL)/itk3.0
• set VSIM_LIBRARY=$(MODEL_TECH_TCL)/vsim
7. Initializes the simulator’s Tcl interpreter.
8. Checks for a valid license (a license is not checked out unless specified by a
modelsim.ini setting or command line option).
9. The next four steps relate to initializing the graphical user interface.
10. Sets Tcl variable MTI_LIB_DIR=$(MODEL_TECH_TCL)
11. Loads $(MTI_LIB_DIR)/vsim/pref.tcl.
12. Loads GUI preferences, project file, etc. from the registry (Windows) or
$(HOME)/.modelsim (UNIX).
13. Searches for the modelsim.tcl file by evaluating the following conditions:
• use MODELSIM_TCL environment variable if it exists (if MODELSIM_TCL is a list of files, each file is loaded in the order that it appears in the list); else
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• use ./modelsim.tcl; else
• use $(HOME)/modelsim.tcl if it exists
That completes the initialization sequence. Also note the following about the modelsim.ini file:
•
When you change the working directory within ModelSim, the tool reads the [library],
[vcom], and [vlog] sections of the local modelsim.ini file. When you make changes in the compiler or simulator options dialog or use the vmap command, the tool updates the appropriate sections of the file.
•
The pref.tcl file references the default .ini file via the [GetPrivateProfileString] Tcl command. The .ini file that is read will be the default file defined at the time pref.tcl is loaded.
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Index
— Symbols —
#, comment character,
$disable_signal_spy,
$enable_signal_spy,
$finish behavior, customizing,
$unit scope, visibility in SV declarations,
.ini control variables
AssertFile,
AssertionDebug,
AssertionFormat,
AssertionFormatBreak,
AssertionFormatError,
AssertionFormatFail,
AssertionFormatFatal,
AssertionFormatNote,
AssertionFormatWarning,
BreakOnAssertion,
CheckPlusargs,
CheckpointCompressMode,
CommandHistory,
ConcurrentFileLimit,
DatasetSeparator,
DefaultForceKind,
DefaultRadix,
DefaultRestartOptions,
DelayFileOpen,
DumpportsCollapse,
GenerateFormat,
GlobalSharedObjectList,
IgnoreError,
IgnoreFailure,
IgnoreNote,
IgnoreWarning,
IterationLimit,
License,
LockedMemory,
NumericStdNoWarnings,
PathSeparator,
Resolution,
RunLength,
Startup,
StdArithNoWarnings,
ToggleMaxIntValues,
TranscriptFile,
UnbufferedOutput,
UseCsupV2,
UserTimeUnit,
Veriuser,
WarnConstantChange,
WaveSignalNameWidth,
WLFCacheSize,
WLFCollapseMode,
WLFCompress,
WLFDeleteOnQuit,
WLFFilename,
WLFOptimize,
WLFSaveAllRegions,
WLFSizeLimit,
WLFTimeLimit,
.ini variables set simulator control with GUI,
.modelsim file in initialization sequence,
purpose,
.so, shared object file loading PLI/VPI/DPI C applications,
loading PLI/VPI/DPI C++ applications,
— Numerics —
0-In tools setting environment variable,
1076, IEEE Std,
differences between versions,
1364, IEEE Std,
,
64-bit libraries,
64-bit time now variable,
Tcl time commands,
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64-bit vsim, using with 32-bit FLI apps,
— A —
ACC routines,
accelerated packages,
access hierarchical objects,
Active Processes pane,
see also windows, Active Processes pane
architecture simulator state variable,
archives described,
argc simulator state variable,
arguments passing to a DO file,
arithmetic package warnings, disabling,
AssertFile .ini file variable,
AssertionDebug .ini variable,
AssertionFormat .ini file variable,
AssertionFormatBreak .ini file variable,
AssertionFormatError .ini file variable,
AssertionFormatFail .ini file variable,
AssertionFormatFatal .ini file variable,
AssertionFormatNote .ini file variable,
AssertionFormatWarning .ini file variable,
assertions file and line number,
message display,
messages turning off,
setting format of messages,
warnings, locating,
— B —
bad magic number error message,
base (radix)
List window,
Wave window,
batch-mode simulations,
BindAtCompile .ini file variable,
binding, VHDL, default,
blocking assignments,
bookmarks
Source window,
Wave window,
break stop simulation run,
BreakOnAssertion .ini file variable,
breakpoints deleting,
setting,
Source window, viewing in,
.bsm file,
buffered/unbuffered output,
busses
RTL-level, reconstructing,
user-defined,
— C —
C applications compiling and linking,
C++ applications compiling and linking,
Call Stack pane,
cancelling scheduled events, performance,
causality, tracing in Dataflow window,
cell libraries,
chasing X,
-check_synthesis argument warning message,
CheckPlusargs .ini file variable (VLOG),
CheckpointCompressMode .ini file variable,
CheckSynthesis .ini file variable,
clock change, sampling signals at,
clock cycles display in timeline,
collapsing time and delta steps,
colorization, in Source window,
columns hide/showing in GUI,
moving,
sorting by,
combining signals, busses,
CommandHistory .ini file variable,
command-line mode,
commands event watching in DO file,
system,
VSIM Tcl commands,
comment character
Tcl and DO files,
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compare signal, virtual restrictions,
compare simulations,
compilation multi-file issues (SystemVerilog),
compilation unit scope,
compile order auto generate,
changing,
SystemVerilog packages,
compiler directives,
IEEE Std 1364-2000,
XL compatible compiler directives,
compiling overview,
changing order in the GUI,
grouping files,
order, changing in projects,
properties, in projects,
range checking in VHDL,
Verilog,
incremental compilation,
XL ’uselib compiler directive,
XL compatible options,
VHDL,
VITAL packages,
compiling C code, gcc,
component, default binding rules,
Compressing files
VCD tasks,
ConcurrentFileLimit .ini file variable,
configuration simulator state variable,
configurations
Verilog,
connectivity, exploring,
context menus
Library tab,
convert real to time,
convert time to real,
cursors adding, deleting, locking, naming,
link to Dataflow window,
measuring time with,
trace events with,
Wave window,
customizing via preference variables,
— D —
deltas explained,
Dataflow window,
extended mode,
pan,
zoom,
see also windows, Dataflow window
dataflow.bsm file,
Dataset Browser,
Dataset Snapshot,
datasets,
managing,
opening,
restrict dataset prefix display,
view structure,
DatasetSeparator .ini file variable,
debugging the design, overview,
default binding
BindAtCompile .ini file variable,
disabling,
default binding rules,
Default editor, changing,
DefaultForceKind .ini file variable,
DefaultRadix .ini file variable,
DefaultRestartOptions .ini variable,
DefaultRestartOptions variable,
delay delta delays,
modes for Verilog models,
DelayFileOpen .ini file variable,
deleting library contents,
delta collapsing,
delta simulator state variable,
deltas in List window,
referencing simulator iteration as a simulator state variable,
dependent design units,
descriptions of HDL items,
design library creating,
logical name, assigning,
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mapping search rules,
resource type,
VHDL design units,
working type,
design object icons, described,
design units,
DEVICE matching to specify path delays,
dialogs
Runtime Options,
Direct Programming Interface,
directories moving libraries,
disable_signal_spy,
DisableOpt .ini file variable,
display preferences
Wave window,
distributed delay mode,
dividers
Wave window,
DLL files, loading,
DO files (macros) error handling,
executing at startup,
parameters, passing to,
Tcl source command,
docking window panes,
DOPATH environment variable,
DPI export TFs,
missing DPI import function,
registering applications,
use flow,
DPI access routines,
DPI export TFs,
DPI/VPI/PLI,
drivers
Dataflow Window,
show in Dataflow window,
Wave window,
dumpports tasks, VCD files,
DumpportsCollapse .ini file variable,
— E —
Editing in notepad windows,
in the Main window,
in the Source window,
EDITOR environment variable,
editor, default, changing,
embedded wave viewer,
empty port name warning,
enable_signal_spy,
ENDFILE function,
ENDLINE function,
entities default binding rules,
entity simulator state variable,
environment variables,
accessed during startup,
expansion,
referencing from command line,
referencing with VHDL FILE variable,
setting,
setting in Windows,
TranscriptFile, specifying location of,
used in Solaris linking for FLI,
used in Solaris linking for
PLI/VPI/DPI/FLI,
using with location mapping,
variable substitution using Tcl,
error can’t locate C compiler,
Error .ini file variable,
errors bad magic number,
DPI missing import function,
getting more information,
severity level, changing,
SystemVerilog, missing declaration,
Tcl_init error,
VSIM license lost,
escaped identifiers,
event order in Verilog simulation,
event queues,
event watching commands, placement of,
events, tracing,
exit codes,
expand
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environment variables,
expand net,
Explicit .ini file variable,
export TFs, in DPI,
Expression Builder,
configuring a List trigger with,
saving expressions to Tcl variable,
— F —
F8 function key,
Fatal .ini file variable,
File compression
VCD tasks,
file I/O
TextIO package,
file-line breakpoints,
files
.modelsim,
files, grouping for compile,
filter processes,
filtering signals in Objects window,
folders, in projects,
fonts controlling in X-sessions,
scaling,
force command defaults,
format file,
Wave window,
FPGA libraries, importing,
Function call, debugging,
functions virtual,
— G —
generate statements, Veilog,
GenerateFormat .ini file variable,
GenerateLoopIterationMax .ini file variable,
GenerateRecursionDepthMax .ini variable,
get_resolution() VHDL function,
global visibility
PLI/FLI shared objects,
GLOBALPATHPULSE matching to specify path delays,
GlobalSharedObjectsList .ini file variable,
graphic interface,
grouping files for compile,
grouping objects, Monitor window,
groups in wave window,
GUI_expression_format
GUI expression builder,
— H —
Hazard .ini file variable (VLOG),
hazards limitations on detection,
hierarchy driving signals in,
,
forcing signals in,
,
,
referencing signals in,
,
,
releasing signals in,
highlighting, in Source window,
history of commands shortcuts for reuse,
HOLD matching to Verilog,
HOME environment variable,
HOME_0IN environment variable,
— I —
I/O
TextIO package,
icons shapes and meanings,
identifiers escaped,
ieee .ini file variable,
IEEE libraries,
IEEE Std 1076,
differences between versions,
IEEE Std 1364,
IgnoreError .ini file variable,
IgnoreFailure .ini file variable,
IgnoreNote .ini file variable,
IgnoreVitalErrors .ini file variable,
IgnoreWarning .ini file variable,
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importing FPGA libraries,
Incremental .ini file variable,
incremental compilation automatic,
manual,
with Verilog,
index checking,
$init_signal_driver,
init_signal_driver,
$init_signal_spy,
init_signal_spy,
,
init_usertfs function,
initialization sequence,
inlining
VHDL subprograms,
input ports matching to INTERCONNECT,
matching to PORT,
INTERCONNECT matching to input ports,
interconnect delays,
IOPATH matching to specify path delays,
iteration_limit, infinite zero-delay loops,
IterationLimit .ini file variable,
— K —
keyboard shortcuts
List window,
Main window,
Source window,
Wave window,
keywords
SystemVerilog,
— L —
-L work,
language templates,
language versions, VHDL,
libraries
64-bit and 32-bit in same library,
creating,
design libraries, creating,
design library types,
design units,
group use, setting up,
IEEE,
importing FPGA libraries,
mapping from the command line,
from the GUI,
hierarchically,
search rules,
modelsim_lib,
moving,
multiple libraries with common modules,
naming,
predefined,
refreshing library images,
resource libraries,
std library,
Synopsys,
Verilog,
VHDL library clause,
working libraries,
working vs resource,
working with contents of,
library map file, Verilog configurations,
library mapping, overview,
library maps, Verilog 2001,
library simulator state variable,
library, definition,
License .ini file variable,
licensing
License variable in .ini file,
List pane
List window,
,
setting triggers,
LM_LICENSE_FILE environment variable,
loading the design, overview,
Locals window,
see also windows, Locals window
location maps, referencing source files,
locations maps specifying source files with,
lock message,
LockedMemory .ini file variable,
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locking cursors,
log file overview,
long simulations saving at intervals,
— M —
MacroNestingLevel simulator state variable,
macros (DO files),
creating from a saved transcript,
depth of nesting, simulator state variable,
error handling,
parameters as a simulator state variable (n),
passing,
total number passed,
startup macros,
Main window,
mapping libraries from the command line,
hierarchically,
symbols
Dataflow window,
mapping libraries, library mapping,
math_complex package,
math_real package,
MDI frame,
MDI pane tab groups,
memories displaying the contents of,
navigation,
saving formats,
selecting memory instances,
viewing contents,
viewing multiple instances,
memory modeling in VHDL,
memory leak, cancelling scheduled events,
Memory pane,
pane
Memory pane
memory tab memories you can view,
Memory window,
see also windows, Memory window
message system,
Message Viewer tab,
Messages,
messages,
bad magic number,
empty port name warning,
exit codes,
getting more information,
lock message,
long description,
message system variables,
metavalue detected,
redirecting,
sensitivity list warning,
suppressing warnings from arithmetic packages,
Tcl_init error,
too few port connections,
turning off assertion messages,
VSIM license lost,
warning, suppressing,
metavalue detected warning,
MGC_LOCATION_MAP env variable,
MGC_LOCATION_MAP variable,
MinGW gcc,
missing DPI import function,
MODEL_TECH environment variable,
MODEL_TECH_TCL environment variable,
modeling memory in VHDL,
MODELSIM environment variable,
modelsim.ini
found by the tool,
default to VHDL93,
delay file opening with,
environment variables in,
force command default, setting,
hierarchical library mapping,
opening VHDL files,
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restart command defaults, setting,
startup file, specifying with,
transcript file created from,
turning off arithmetic package warnings,
turning off assertion messages,
modelsim.tcl,
modelsim_lib,
path to,
MODELSIM_PREFERENCES variable,
MODELSIM_TCL environment variable,
modes of operation,
Modified field, Project tab,
modules handling multiple, common names,
Monitor window grouping/ungrouping objects,
monitor window,
mouse shortcuts
Main window,
Source window,
Wave window,
.mpf file,
loading from the command line,
order of access during startup,
msgmode .ini file variable,
msgmode variable,
mti_cosim_trace environment variable,
mti_inhibit_inline attribute,
MTI_TF_LIMIT environment variable,
multi-file compilation issues, SystemVerilog,
MultiFileCompilationUnit .ini file variable,
multiple document interface,
Multiple simulations,
— N —
n simulator state variable,
Name field
Project tab,
name visibility in Verilog generates,
names, modules with the same,
negative timing
$setuphold/$recovery,
algorithm for calculating delays,
check limits,
nets
Dataflow window, displaying in,
values of displaying in Objects window,
saving as binary log file,
waveforms, viewing,
Nlview widget Symlib format,
NoCaseStaticError .ini file variable,
NOCHANGE matching to Verilog,
NoDebug .ini file variable (VCOM),
NoDebug .ini file variable (VLOG),
NoIndexCheck .ini file variable,
NOMMAP environment variable,
non-blocking assignments,
NoOthersStaticError .ini file variable,
NoRangeCheck .ini file variable,
Note .ini file variable,
Notepad windows, text editing,
-notrigger argument,
NoVital .ini file variable,
NoVitalCheck .ini file variable,
Now simulator state variable,
now simulator state variable,
numeric_bit package,
numeric_std package,
disabling warning messages,
NumericStdNoWarnings .ini file variable,
— O —
object defined,
objects virtual,
Objects window,
see also windows, Objects window
operating systems supported, See Installation
Guide
optimizations
VHDL subprogram inlining,
Optimize_1164 .ini file variable,
ordering files for compile,
organizing projects with folders,
organizing windows, MDI pane,
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others .ini file variable,
overview, simulation tasks,
— P —
packages standard,
textio,
util,
VITAL 1995,
VITAL 2000,
page setup
Dataflow window,
Wave window,
pan, Dataflow window,
panes docking and undocking,
Memory panes,
parameters making optional,
using with macros,
path delay mode,
path delays,matching to DEVICE statements,
path delays,matching to
GLOBALPATHPULSE statements,
path delays,matching to IOPATH statements,
path delays,matching to PATHPULSE statements,
pathnames hiding in Wave window,
PATHPULSE matching to specify path delays,
PathSeparator .ini file variable,
PedanticErrors .ini file variable,
performance cancelling scheduled events,
PERIOD matching to Verilog,
platforms supported, See Installation Guide
PLI loading shared objects with global symbol visibility,
specifying which apps to load,
Veriuser entry,
PLI/VPI,
tracing,
PLI/VPI/DPI,
registering DPIapplications,
specifying the DPI file to load,
PLIOBJS environment variable,
,
PORT matching to input ports,
Port driver data, capturing,
Postscript saving a waveform in,
saving the Dataflow display in,
precedence of variables,
precision, simulator resolution,
preference variables
.ini files, located in,
editing,
saving,
preferences saving,
Wave window display,
PrefMain(EnableCommandHelp),
PrefMain(ShowFilePane) preference variable,
PrefMemory(ExpandPackedMem) variable,
primitives, symbols in Dataflow window,
printing
Dataflow window display,
waveforms in the Wave window,
Programming Language Interface,
project tab information in,
sorting,
projects,
accessing from the command line,
adding files to,
benefits,
close,
compile order,
changing,
compiler properties in,
compiling files,
creating,
creating simulation configurations,
folders in,
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grouping files in,
loading a design,
MODELSIM environment variable,
open and existing,
overview,
protected types,
— Q —
quick reference table of simulation tasks,
Quiet .ini file variable
VCOM,
Quiet .ini file variable (VLOG),
— R —
race condition, problems with event order,
radix
List window,
SystemVerilog types,
,
Wave window,
range checking,
readers and drivers,
real type, converting to time,
reconstruct RTL-level design busses,
RECOVERY matching to Verilog,
$recovery,
RECREM matching to Verilog,
redirecting messages, TranscriptFile,
refreshing library images,
regions virtual,
registers values of displaying in Objects window,
saving as binary log file,
waveforms, viewing,
REMOVAL matching to Verilog,
report simulator control,
simulator state,
RequireConfigForAllDefaultBinding variable,
resolution returning as a real,
verilog simulation,
VHDL simulation,
Resolution .ini file variable,
resolution simulator state variable,
resource libraries,
restart command defaults,
toolbar button,
results, saving simulations,
RTL-level design busses reconstructing,
RunLength .ini file variable,
Runtime Options dialog,
— S —
saveLines preference variable,
saving simulation options in a project,
waveforms,
scaling fonts,
SDF disabling timing checks,
errors and warnings,
instance specification,
interconnect delays,
mixed VHDL and Verilog designs,
specification with the GUI,
troubleshooting,
Verilog
$sdf_annotate system task,
optional conditions,
optional edge specifications,
rounded timing values,
SDF to Verilog construct matching,
VHDL resolving errors,
SDF to VHDL generic matching,
SDF DEVICE matching to Verilog constructs,
SDF GLOBALPATHPULSE matching to Verilog constructs,
SDF HOLD matching to Verilog constructs,
SDF INTERCONNECT matching to Verilog constructs,
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SDF IOPATH matching to Verilog constructs,
SDF NOCHANGE matching to Verilog constructs,
SDF PATHPULSE matching to Verilog constructs,
SDF PERIOD matching to Verilog constructs,
SDF PORT matching to Verilog constructs,
SDF RECOVERY matching to Verilog constructs,
SDF RECREM matching to Verilog constructs,
SDF REMOVAL matching to Verilog constructs,
SDF SETUPHOLD matching to Verilog constructs,
SDF SKEW matching to Verilog constructs,
SDF WIDTH matching to Verilog constructs,
$sdf_done,
searching
Expression Builder,
Verilog libraries,
sensitivity list warning,
set simulator control with GUI,
SETUP matching to Verilog,
SETUPHOLD matching to Verilog,
$setuphold,
severity, changing level for errors,
shared objects loading FLI applications
loading PLI/VPI/DPI C applications,
loading PLI/VPI/DPI C++ applications,
loading with global symbol visibility,
Shortcuts text editing,
shortcuts command history,
command line caveat,
List window,
Main window,
Source window,
Wave window,
show drivers
Dataflow window,
Wave window,
Show_ WarnMatchCadence .ini file variable,
Show_BadOptionWarning .ini file variable,
Show_Lint .ini file variable
VCOM,
Show_Lint .ini file variable (VLOG),
Show_source .ini file variable
VCOM,
Show_source .ini file variable (VLOG),
Show_VitalChecksOpt .ini file variable,
Show_VitalChecksWarning .ini file variable,
Show_WarnCantDoCoverage .ini file variable,
Show_WarnCantDoCoverage variable,
Show_Warning1 .ini file variable,
Show_Warning10 .ini file variable,
Show_Warning2 .ini file variable,
Show_Warning3 .ini file variable,
Show_Warning4 .ini file variable,
Show_Warning5 .ini file variable,
Show_Warning9 .ini file variable,
Show_WarnLocallyStaticError variable,
signal groups in wave window,
Signal Spy,
,
disable,
enable,
,
$signal_force,
signal_force,
,
$signal_release,
signal_release,
signals combining into a user-defined bus,
Dataflow window, displaying in,
driving in the hierarchy,
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filtering in the Objects window,
hierarchy driving in,
referencing in,
releasing anywhere in,
releasing in,
sampling at a clock change,
transitions, searching for,
types, selecting which to view,
values of displaying in Objects window,
forcing anywhere in the hierarchy,
,
saving as binary log file,
virtual,
waveforms, viewing,
simulating batch mode,
command-line mode,
comparing simulations,
default run length,
iteration limit,
saving dataflow display as a Postscript file,
saving options in a project,
saving simulations,
saving waveform as a Postscript file,
Verilog,
delay modes,
hazard detection,
resolution limit,
XL compatible simulator options,
VHDL,
viewing results in List pane,
viewing results in List window,
VITAL packages,
simulating the design, overview,
simulation basic steps for,
Simulation Configuration creating,
simulation task overview,
simulations event order in,
saving results,
saving results at intervals,
simulator control with .ini variables,
simulator resolution returning as a real,
Verilog,
VHDL,
simulator state variables,
sizetf callback function,
SKEW matching to Verilog,
so, shared object file loading PLI/VPI/DPI C applications,
loading PLI/VPI/DPI C++ applications,
source files, referencing with location maps,
source files, specifying with location maps,
source highlighting, customizing,
source libraries arguments supporting,
Source window,
colorization,
tab stops in,
see also windows, Source window
specify path delays matching to DEVICE construct,
matching to GLOBALPATHPULSE construct,
matching to IOPATH statements,
matching to PATHPULSE construct,
standards supported,
startup environment variables access during,
files accessed during,
macro in the modelsim.ini file,
macros,
startup macro in command-line mode,
using a startup file,
Startup .ini file variable,
state variables,
status bar
Main window,
Status field
Project tab,
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std .ini file variable,
std_arith package disabling warning messages,
std_developerskit .ini file variable,
std_logic_arith package,
std_logic_signed package,
std_logic_textio,
std_logic_unsigned package,
StdArithNoWarnings .ini file variable,
STDOUT environment variable,
steps for simulation, overview,
subprogram inlining,
subprogram write is ambiguous error, fixing,
Suppress .ini file variable,
sv_std .ini file variable,
symbol mapping
Dataflow window,
symbolic link to design libraries (UNIX),
synopsys .ini file variable,
Synopsys libraries,
syntax highlighting,
synthesis rule compliance checking,
system calls
VCD,
Verilog,
system commands,
system tasks proprietary,
VCD,
Verilog,
Verilog-XL compatible,
SystemVerilog keyword considerations,
multi-file compilation,
suppported implementation details,
SystemVerilog DPI specifying the DPI file to load,
SystemVerilog types radix,
— T —
tab groups,
tab stops
Source window,
Tcl, ?? to
command separator,
command substitution,
command syntax,
evaluation order,
history shortcuts,
preference variables,
relational expression evaluation,
time commands,
variable substitution,
VSIM Tcl commands,
Tcl_init error message,
temp files, VSOUT,
testbench, accessing internal objectsfrom,
text and command syntax,
Text editing,
TEXTIO buffer, flushing,
TextIO package alternative I/O files,
containing hexadecimal numbers,
dangling pointers,
ENDFILE function,
ENDLINE function,
file declaration,
implementation issues,
providing stimulus,
standard input,
standard output,
WRITE procedure,
WRITE_STRING procedure,
TF routines,
TFMPC time explanation,
measuring in Wave window,
time resolution as a simulator state variable,
time collapsing,
time resolution in Verilog,
in VHDL,
time type converting to real,
ModelSim User’s Manual, v6.2g
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timeline display clock cycles,
timescale directive warning investigating,
timing
$setuphold/$recovery,
disabling checks,
negative check limits described,
TMPDIR environment variable,
to_real VHDL function,
to_time VHDL function,
toggle coverage max VHDL integer values,
too few port connections, explanation,
tool structure,
toolbar
Dataflow window,
Main window,
tracing events,
source of unknown,
transcript disable file creation,
file name, specifed in modelsim.ini,
saving,
using as a DO file,
Transcript window changing buffer size,
changing line count,
TranscriptFile .ini file variable,
triggers, in the List window,
triggers, in the List window, setting,
troubleshooting
DPI, missing import funtion,
TSSI type in VCD files,
converting real to time,
converting time to real,
Type field, Project tab,
types virtual,
— U —
UnbufferedOutput .ini file variable,
ungrouping in wave window,
ungrouping objects, Monitor window,
unit delay mode,
unknowns, tracing,
use clause, specifying a library,
use flow
DPI,
UseCsupV2 .ini file variable,
user-defined bus,
UserTimeUnit .ini file variable,
util package,
— V —
values of HDL items,
variables,
environment,
expanding environment variables,
LM_LICENSE_FILE,
precedence between .ini and .tcl,
setting environment variables,
simulator state variables current settings report,
iteration number,
name of entity or module as a variable,
resolution,
simulation time,
values of displaying in Objects window,
saving as binary log file,
VCD files capturing port driver data,
case sensitivity,
creating,
dumpports tasks,
from VHDL source to VCD output,
stimulus, using as,
supported TSSI states,
VCD system tasks,
Verilog
ACC routines,
capturing port driver data with -dumpports,
cell libraries,
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compiler directives,
compiling and linking PLI C applications,
compiling and linking PLI C++ applications,
compiling design units,
compiling with XL ’uselib compiler directive,
configurations,
DPI access routines,
event order in simulation,
generate statements,
language templates,
library usage,
SDF annotation,
sdf_annotate system task,
simulating,
delay modes,
XL compatible options,
simulation hazard detection,
simulation resolution limit,
source code viewing,
standards,
system tasks,
TF routines,
XL compatible compiler options,
XL compatible routines,
XL compatible system tasks,
verilog .ini file variable,
Verilog 2001 disabling support,
Verilog PLI/VP/DPII registering VPI applications,
Verilog PLI/VPI
64-bit support in the PLI,
debugging PLI/VPI code,
Verilog PLI/VPI/DPI compiling and linking PLI/VPI C++ applications,
compiling and linking PLI/VPI/CPI C applications,
PLI callback reason argument,
PLI support for VHDL objects,
registering PLI applications,
specifying the PLI/VPI file to load,
Verilog-XL compatibility with,
,
Veriuser .ini file variable,
Veriuser, specifying PLI applications,
veriuser.c file,
VHDL compiling design units,
creating a design library,
delay file opening,
dependency checking,
file opening delay,
language templates,
language versions,
library clause,
object support in PLI,
optimizations inlining,
simulating,
source code viewing,
standards,
timing check disabling,
VITAL package,
VHDL utilities,
,
,
,
get_resolution(),
to_real(),
to_time(),
VHDL-1987, compilation problems,
VHDL-1993, enabling support for,
VHDL-2002, enabling support for,
VHDL93 .ini file variable,
viewing,
library contents,
waveforms,
virtual compare signal, restrictions,
virtual hide command,
virtual objects,
virtual functions,
virtual regions,
virtual signals,
virtual types,
virtual region command,
virtual regions reconstruct RTL hierarchy,
virtual save command,
virtual signal command,
ModelSim User’s Manual, v6.2g
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439
virtual signals reconstruct RTL-level design busses,
reconstruct the original RTL hierarchy,
virtual hide command,
visibility of declarations in $unit,
VITAL compiling and simulating with accelerated
VITAL packages,
disabling optimizations for debugging,
specification and source code,
VITAL packages,
vital95 .ini file variable,
vlog95compat .ini file variable,
VPI, registering applications,
VPI/PLI,
VPI/PLI/DPI,
compiling and linking C applications,
compiling and linking C++ applications,
VSIM license lost,
VSOUT temp file,
— W —
WarnConstantChange .ini file variable,
Warning .ini file variable,
warnings empty port name,
exit codes,
getting more information,
messages, long description,
metavalue detected,
severity level, changing,
suppressing VCOM warning messages,
suppressing VLOG warning messages,
suppressing VSIM warning messages,
Tcl initialization error 2,
too few port connections,
turning off warnings from arithmetic packages,
waiting for lock,
watching a signal value,
wave groups,
add items to existing,
creating,
deleting,
drag from Wave to List,
drag from Wave to Transcript,
removing items from existing,
ungrouping,
Wave Log Format (WLF) file,
wave log format (WLF) file
wave viewer, Dataflow window,
Wave window,
docking and undocking,
in the Dataflow window,
saving layout,
timeline display clock cycles,
waveform logfile overview,
waveforms,
optimize viewing of,
viewing,
WaveSignalNameWidth .ini file variable,
WIDTH matching to Verilog,
windows
Active Processes pane,
Dataflow window,
toolbar,
zooming,
List window,
,
display properties of,
formatting HDL items,
saving data to a file,
setting triggers,
Locals window,
Main window,
status bar,
text editing,
time and delta display,
toolbar,
Memory window,
monitor,
Objects window,
Signals window
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VHDL and Verilog items viewed in,
Source window,
text editing,
viewing HDL source code,
Variables window
VHDL and Verilog items viewed in,
Wave window,
adding HDL items to,
cursor measurements,
display preferences,
display range (zoom), changing,
format file, saving,
path elements, changing,
time cursors,
zooming,
WLF file parameters cache size,
collapse mode,
compression,
delete on quit,
filename,
optimization,
overview,
size limit,
time limit,
WLF files collapsing events,
optimizing waveform viewing,
saving,
saving at intervals,
WLFCacheSize .ini file variable,
WLFCollapseMode .ini file variable,
WLFCompress .ini variable,
WLFDeleteOnQuit .ini variable,
WLFFilename .ini file variable,
WLFSaveAllRegions .ini variable,
WLFSizeLimit .ini variable,
WLFTimeLimit .ini variable,
work library,
creating,
workspace,
WRITE procedure, problems with,
— X —
X tracing unknowns,
.Xdefaults file, controlling fonts,
X-session controlling fonts,
— Z —
zero delay elements,
zero delay mode,
zero-delay loop, infinite,
zero-delay oscillation,
zero-delay race condition,
zoom
Dataflow window,
saving range with bookmarks,
zooming window panes,
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RESPECT TO SOFTWARE OR OTHER MATERIAL PROVIDED UNDER THIS AGREEMENT. MENTOR
GRAPHICS AND ITS LICENSORS SPECIFICALLY DISCLAIM ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT OF
INTELLECTUAL PROPERTY.
6.
LIMITATION OF LIABILITY. EXCEPT WHERE THIS EXCLUSION OR RESTRICTION OF LIABILITY
WOULD BE VOID OR INEFFECTIVE UNDER APPLICABLE LAW, IN NO EVENT SHALL MENTOR GRAPHICS
OR ITS LICENSORS BE LIABLE FOR INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
(INCLUDING LOST PROFITS OR SAVINGS) WHETHER BASED ON CONTRACT, TORT OR ANY OTHER
LEGAL THEORY, EVEN IF MENTOR GRAPHICS OR ITS LICENSORS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES. IN NO EVENT SHALL MENTOR GRAPHICS' OR ITS LICENSORS'
LIABILITY UNDER THIS AGREEMENT EXCEED THE AMOUNT PAID BY YOU FOR THE SOFTWARE OR
SERVICE GIVING RISE TO THE CLAIM. IN THE CASE WHERE NO AMOUNT WAS PAID, MENTOR
GRAPHICS AND ITS LICENSORS SHALL HAVE NO LIABILITY FOR ANY DAMAGES WHATSOEVER. THE
PROVISIONS OF THIS SECTION 6 SHALL SURVIVE THE EXPIRATION OR TERMINATION OF THIS
AGREEMENT.
7.
LIFE ENDANGERING ACTIVITIES. NEITHER MENTOR GRAPHICS NOR ITS LICENSORS SHALL BE
LIABLE FOR ANY DAMAGES RESULTING FROM OR IN CONNECTION WITH THE USE OF SOFTWARE IN
ANY APPLICATION WHERE THE FAILURE OR INACCURACY OF THE SOFTWARE MIGHT RESULT IN
DEATH OR PERSONAL INJURY.
THE PROVISIONS OF THIS SECTION 7 SHALL SURVIVE THE
EXPIRATION OR TERMINATION OF THIS AGREEMENT.
8.
INDEMNIFICATION. YOU AGREE TO INDEMNIFY AND HOLD HARMLESS MENTOR GRAPHICS AND ITS
LICENSORS FROM ANY CLAIMS, LOSS, COST, DAMAGE, EXPENSE, OR LIABILITY, INCLUDING
ATTORNEYS' FEES, ARISING OUT OF OR IN CONNECTION WITH YOUR USE OF SOFTWARE AS
DESCRIBED IN SECTION 7. THE PROVISIONS OF THIS SECTION 8 SHALL SURVIVE THE EXPIRATION OR
TERMINATION OF THIS AGREEMENT.
9.
INFRINGEMENT.
9.1. Mentor Graphics will defend or settle, at its option and expense, any action brought against you alleging that
Software infringes a patent or copyright or misappropriates a trade secret in the United States, Canada, Japan, or member state of the European Patent Office. Mentor Graphics will pay any costs and damages finally awarded against you that are attributable to the infringement action. You understand and agree that as conditions to Mentor
Graphics' obligations under this section you must: (a) notify Mentor Graphics promptly in writing of the action;
(b) provide Mentor Graphics all reasonable information and assistance to defend or settle the action; and (c) grant
Mentor Graphics sole authority and control of the defense or settlement of the action.
9.2. If an infringement claim is made, Mentor Graphics may, at its option and expense: (a) replace or modify Software so that it becomes noninfringing; (b) procure for you the right to continue using Software; or (c) require the return of
Software and refund to you any license fee paid, less a reasonable allowance for use.
9.3. Mentor Graphics has no liability to you if infringement is based upon: (a) the combination of Software with any product not furnished by Mentor Graphics; (b) the modification of Software other than by Mentor Graphics; (c) the use of other than a current unaltered release of Software; (d) the use of Software as part of an infringing process; (e) a product that you make, use or sell; (f) any Beta Code contained in Software; (g) any Software provided by Mentor
Graphics’ licensors who do not provide such indemnification to Mentor Graphics’ customers; or (h) infringement by you that is deemed willful. In the case of (h) you shall reimburse Mentor Graphics for its attorney fees and other costs related to the action upon a final judgment.
9.4. THIS SECTION IS SUBJECT TO SECTION 6 ABOVE AND STATES THE ENTIRE LIABILITY OF MENTOR
GRAPHICS AND ITS LICENSORS AND YOUR SOLE AND EXCLUSIVE REMEDY WITH RESPECT TO
ANY ALLEGED PATENT OR COPYRIGHT INFRINGEMENT OR TRADE SECRET MISAPPROPRIATION
BY ANY SOFTWARE LICENSED UNDER THIS AGREEMENT.
10. TERM. This Agreement remains effective until expiration or termination. This Agreement will immediately terminate upon notice if you exceed the scope of license granted or otherwise fail to comply with the provisions of Sections 1, 2, or
4. For any other material breach under this Agreement, Mentor Graphics may terminate this Agreement upon 30 days written notice if you are in material breach and fail to cure such breach within the 30 day notice period. If Software was provided for limited term use, this Agreement will automatically expire at the end of the authorized term. Upon any termination or expiration, you agree to cease all use of Software and return it to Mentor Graphics or certify deletion and destruction of Software, including all copies, to Mentor Graphics’ reasonable satisfaction.
11. EXPORT. Software is subject to regulation by local laws and United States government agencies, which prohibit export or diversion of certain products, information about the products, and direct products of the products to certain countries and certain persons. You agree that you will not export any Software or direct product of Software in any manner without first obtaining all necessary approval from appropriate local and United States government agencies.
12. RESTRICTED RIGHTS NOTICE. Software was developed entirely at private expense and is commercial computer software provided with RESTRICTED RIGHTS. Use, duplication or disclosure by the U.S. Government or a U.S.
Government subcontractor is subject to the restrictions set forth in the license agreement under which Software was obtained pursuant to DFARS 227.7202-3(a) or as set forth in subparagraphs (c)(1) and (2) of the Commercial Computer
Software - Restricted Rights clause at FAR 52.227-19, as applicable. Contractor/manufacturer is Mentor Graphics
Corporation, 8005 SW Boeckman Road, Wilsonville, Oregon 97070-7777 USA.
13. THIRD PARTY BENEFICIARY. For any Software under this Agreement licensed by Mentor Graphics from Microsoft or other licensors, Microsoft or the applicable licensor is a third party beneficiary of this Agreement with the right to enforce the obligations set forth herein.
14. AUDIT RIGHTS. You will monitor access to, location and use of Software. With reasonable prior notice and during your normal business hours, Mentor Graphics shall have the right to review your software monitoring system and reasonably relevant records to confirm your compliance with the terms of this Agreement, an addendum to this
Agreement or U.S. or other local export laws. Such review may include FLEXlm or FLEXnet report log files that you shall capture and provide at Mentor Graphics’ request. Mentor Graphics shall treat as confidential information all of your information gained as a result of any request or review and shall only use or disclose such information as required by law or to enforce its rights under this Agreement or addendum to this Agreement. The provisions of this section 14 shall survive the expiration or termination of this Agreement.
15. CONTROLLING LAW, JURISDICTION AND DISPUTE RESOLUTION. THIS AGREEMENT SHALL BE
GOVERNED BY AND CONSTRUED UNDER THE LAWS OF THE STATE OF OREGON, USA, IF YOU ARE
LOCATED IN NORTH OR SOUTH AMERICA, AND THE LAWS OF IRELAND IF YOU ARE LOCATED
OUTSIDE OF NORTH OR SOUTH AMERICA. All disputes arising out of or in relation to this Agreement shall be submitted to the exclusive jurisdiction of Portland, Oregon when the laws of Oregon apply, or Dublin, Ireland when the laws of Ireland apply. Notwithstanding the foregoing, all disputes in Asia (except for Japan) arising out of or in relation to this Agreement shall be resolved by arbitration in Singapore before a single arbitrator to be appointed by the Chairman of the Singapore International Arbitration Centre (“SIAC”) to be conducted in the English language, in accordance with the
Arbitration Rules of the SIAC in effect at the time of the dispute, which rules are deemed to be incorporated by reference in this section 15. This section shall not restrict Mentor Graphics’ right to bring an action against you in the jurisdiction where your place of business is located. The United Nations Convention on Contracts for the International Sale of Goods does not apply to this Agreement.
16. SEVERABILITY. If any provision of this Agreement is held by a court of competent jurisdiction to be void, invalid, unenforceable or illegal, such provision shall be severed from this Agreement and the remaining provisions will remain in full force and effect.
17. PAYMENT TERMS AND MISCELLANEOUS. You will pay amounts invoiced, in the currency specified on the applicable invoice, within 30 days from the date of such invoice. Any past due invoices will be subject to the imposition of interest charges in the amount of one and one-half percent per month or the applicable legal rate currently in effect, whichever is lower. Some Software may contain code distributed under a third party license agreement that may provide additional rights to you. Please see the applicable Software documentation for details. This Agreement may only be modified in writing by authorized representatives of the parties. Waiver of terms or excuse of breach must be in writing and shall not constitute subsequent consent, waiver or excuse.
Rev. 060210, Part No. 227900
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