USER`S MANUAL

INSTRUCTION SET S3F80N8_UM_REV1.10

CONDITION CODES

The opcode of a conditional jump always contains a 4-bit field called the condition code (cc). This specifies under which conditions it is to execute the jump. For example, a conditional jump with the condition code for "equal" after a compare operation only jumps if the two operands are equal. Condition codes are listed in Table 6-6.

The carry (C), zero (Z), sign (S), and overflow (V) flags are used to control the operation of conditional jump instructions.

Table 6-6. Condition Codes

Binary Mnemonic Description

0000 F Always

1000 T Always

0111

(note)

C Carry

1111

(note)

NC No carry

0110

(note)

1110

(note)

Z

NZ

Zero

Not zero

1101

0101

0100

1100

0110

(note)

1110

(note)

PL

MI

OV

NOV

EQ

NE

Plus

Minus

Overflow

No overflow

Equal

Not equal

1001

0001

1010

0010

1111

(note)

0111

(note)

1011

0011

GE

LT

GT

LE

UGE

ULT

UGT

ULE

Greater than or equal

Less than

Greater than

Less than or equal

Unsigned greater than or equal

Unsigned less than

Unsigned greater than

Unsigned less than or equal

–

–

C = 1

C = 0

Z = 1

Z = 0

S = 0

S = 1

V = 1

V = 0

Z = 1

Z = 0

(S XOR V) = 0

(S XOR V) = 1

(Z OR (S XOR V)) = 0

(Z OR (S XOR V)) = 1

C = 0

C = 1

(C = 0 AND Z = 0) = 1

(C OR Z) = 1

NOTES:

1. It indicates condition codes that are related to two different mnemonics but which test the same flag. For example, Z and EQ are both true if the zero flag (Z) is set, but after an ADD instruction, Z would probably be used; after a CP instruction, however, EQ would probably be used.

2. For operations involving unsigned numbers, the special condition codes UGE, ULT, UGT, and ULE must be used.

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