Samsung S3F80JB manual CP Compare, INC Skip LD

INSTRUCTION SETS3F80JB

CP — Compare

CP	dst,src
Operation:	dst – src
	The source operand is compared to (subtracted from) the destination operand, and the
	appropriate flags are set accordingly. The contents of both operands are unaffected by the
	comparison.
Flags:	C: Set if a "borrow" occurred (src > dst); cleared otherwise.
	Z:	Set if the result is "0"; cleared otherwise.
	S:	Set if the result is negative; cleared otherwise.
	V:	Set if arithmetic overflow occurred; cleared otherwise.
	D:	Unaffected.
	H:	Unaffected.

Format:
Bytes Cycles	Opcode	Addr Mode
	(Hex)	dst	src

opc	dst src
opc	src	dst

2	4	A2	r	r
	6	A3	r	lr
3	6	A4	R	R
	6	A5	R	IR

opc

dst

src

3 6 A6 R IM

Examples: 1. Given: R1 = 02H and R2 = 03H:

CP R1,R2 → Set the C and S flags

Destination working register R1 contains the value 02H and source register R2 contains the value 03H. The statement "CP R1,R2" subtracts the R2 value (source/subtrahend) from the R1 value (destination/minuend). Because a "borrow" occurs and the difference is negative, C and S are "1".

2. Given: R1 = 05H and R2 = 0AH:

CP	R1,R2
JP	UGE,SKIP
INC	R1
SKIP LD	R3,R1

In this example, destination working register R1 contains the value 05H which is less than the contents of the source working register R2 (0AH). The statement "CP R1,R2" generates C = "1" and the JP instruction does not jump to the SKIP location. After the statement "LD R3,R1" executes, the value 06H remains in working register R3.

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