Samsung S3C84E5 CP Compare, Operation dst-src, Format Bytes Cycles Opcode Addr Mode Hex Dst Src

INSTRUCTION SET S3C84E5/C84E9/P84E9

CP — Compare

CPdst,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		2		4	A2	r	r
								6	A3	r	lr
		opc		src	dst		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
	The destination working register R1 contains the value 02H and the 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, the C and
	the S flag values are "1".
	2. Given:		R1 = 05H and R2 = 0AH:
		CP		R1,R2
		JP		UGE,SKIP
		INC		R1
		SKIP		LD R3,R1

In this example, the 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 the working register R3.

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