Creating Memory Gaps. NXP CodeWarrior Development Studio

Chapter 13 Linker for AIOP

The dot keyword ("

.

"), is a convenient way to set the linker's place in the current output section.

Listing 13-9 on page 211

shows an example.

Listing 13-9. Skipping areas of memory

SECTIONS

{

GROUP :

{

.ISR_Table : {}

. = 0x2000

} > flash

GROUP :

{

.paramsection : {}

} > flash

}

This example defines two sections. The first section,

.ISRTable

, will be loaded at beginning of the memory area named flash

on the target platform at runtime. The second section,

.paramsection

, will be loaded at the address that is

0x2000

bytes past the beginning of the memory area named flash

.

13.8 Creating Memory Gaps

You can create gaps in memory by performing alignment calculations such as

. = (. + 0x20) & ~0x20;

This kind of calculation can occur between output_specs

, between input_specs,

or even in address_modifiers

. A "." refers to the current address. You may assign the

.

to a specific unallocated address or just do alignment as the example shows. The gap is filled with zeroes, in the case of an alignment (but not with

ALIGN()

).

You can specify an alternate fill pattern with

= <short_value>

, as in

.text : { . = (. + 0x20) & ~0x20; *(.text) } = 0xAB > text short_value

is 2 bytes long. Note that the fill pattern comes before the memory_spec

. You can add a fill to a

GROUP

or to an individual output_spec

section. Fills cannot be added between

.bss

type sections. All calculations must end in a "

;

".

CodeWarrior Development Studio for Advanced Packet Processing Build Tools Reference Manual, Rev.

10.2, 01/2016

Freescale Semiconductor, Inc.

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