Intel 80C186XL, 80C188XL CMP dest, src, Compare String, Cmps dest-string,src-string

INSTRUCTION SET DESCRIPTIONS

Table C-4. Instruction Set (Continued)

Name	Description	Operation	Flags
			Affected
CMP	Compare:	(dest) – (src)	AF
	CMP dest, src		CF
			DF –
	Subtracts the source from the desti-
			IF –
	nation, which may be bytes or words,
			OF
	but does not return the result. The
			PF
	operands are unchanged, but the flags
			SF
	are updated and can be tested by a
			TF –
	subsequent conditional jump
			ZF ¸
	instruction. The comparison reflected
	in the flags is that of the destination to
	the source. If a CMP instruction is
	followed by a JG (jump if greater)
	instruction, for example, the jump is
	taken if the destination operand is
	greater than the source operand.
	Instruction Operands:
	CMP reg, reg
	CMP reg, mem
	CMP mem, reg
	CMP reg, immed
	CMP mem, immed
	CMP accum, immed
CMPS	Compare String:	(dest-string) – (src-string)	AF
	CMPS dest-string,src-string	if	CF
		(DF) = 0	DF –
	Subtracts the destination byte or word
		then	IF –
	from the source byte or word. The
		(SI) ← (SI) + DELTA	OF
	destination byte or word is addressed
		(DI) ← (DI) + DELTA	PF
	by the destination index (DI) register
		else	SF
	and the source byte or word is
		(SI) ← (SI) – DELTA	TF –
	addresses by the source index (SI)
		(DI) ← (DI) – DELTA	ZF ¸
	register. CMPS updates the flags to
	reflect the relationship of the
	destination element to the source
	element but does not alter either
	operand and updates SI and DI to
	point to the next string element.
	Instruction Operands:
	CMP dest-string, src-string
	CMP (repeat) dest-string, src-string

NOTE: The three symbols used in the Flags Affected column are defined as follows:

–the contents of the flag remain unchanged after the instruction is executed ¸? the contents of the flag is undefined after the instruction is executed

the flag is updated after the instruction is executed

C-10