Samsung S3C84E5 user manual Condition Codes Binary Mnemonic Description Flags Set

INSTRUCTION SET S3C84E5/C84E9/P84E9

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				Flags Set
0000	F	Always false	–
1000	T	Always true	–
0111 (1)	C	Carry	C = 1
1111 (1)	NC	No carry	C = 0
0110 (1)	Z	Zero	Z = 1
1110 (1)	NZ	Not zero	Z = 0
1101	PL	Plus	S = 0
0101	MI	Minus	S = 1
0100	OV	Overflow	V = 1
1100	NOV	No overflow	V = 0
0110 (1)	EQ	Equal	Z = 1
1110 (1)	NE	Not equal	Z = 0
1001	GE	Greater than or equal	(S	XOR		V) = 0
0001	LT	Less than	(S XOR			V) = 1
1010	GT	Greater than	(Z	OR (S		XOR	V)) = 0
0010	LE	Less than or equal	(Z	OR (S		XOR	V)) = 1
1111 (1)	UGE	Unsigned greater than or equal	C = 0
0111 (1)	ULT	Unsigned less than	C = 1
1011	UGT	Unsigned greater than	(C = 0		AND Z = 0) = 1
0011	ULE	Unsigned less than or equal	(C	OR	Z) = 1

NOTES:

1.It indicate condition codes which 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. Following a CP instruction, you would probably want to use the instruction EQ.

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

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