Intel 80C186XL, 80C188XL Rotate Through Carry Left, RCL dest, count, Rotate Through Carry Right

INSTRUCTION SET DESCRIPTIONS

Table C-4. Instruction Set (Continued)

Name	Description	Operation	Flags
			Affected
RCL	Rotate Through Carry Left:	(temp) ← count	AF –
	RCL dest, count	do while (temp) ≠ 0	CF
		(tmpcf) ← (CF)	DF –
	Rotates the bits in the byte or word
		(CF) ← high-order bit of (dest)	IF –
	destination operand to the left by the
		(dest) ← (dest) × 2 + (tmpcf)	OF ¸
	number of bits specified in the count	(temp) ← (temp) – 1	PF –
	operand. The carry flag (CF) is treated
		if	SF –
	as "part of" the destination operand;
		count = 1	TF –
	that is, its value is rotated into the low-
		then	ZF –
	order bit of the destination, and itself is
		if
	replaced by the high-order bit of the
		high-order bit of (dest) ≠ (CF)
	destination.
		then
	Instruction Operands:
		(OF) ← 1
	RCL reg, n	else
	RCL mem, n	(OF) ← 0
	RCL reg, CL	else
	RCL mem, CL	(OF) undefined
RCR	Rotate Through Carry Right:	(temp) ← count	AF –
	RCR dest, count	do while (temp) ≠ 0	CF
		(tmpcf) ← (CF)	DF –
	Operates exactly like RCL except that
		(CF) ← low-order bit of (dest)	IF –
	the bits are rotated right instead of left.
		(dest) ← (dest) / 2	OF ¸
	Instruction Operands:	high-order bit of (dest) ← (tmpcf)	PF –
	RCR reg, n	(temp) ← (temp) – 1	SF –
	RCR mem, n	if	TF –
	RCR reg, CL	count = 1	ZF –
	RCR mem, CL	then
		if
		high-order bit of (dest) ≠
		next-to-high-order bit of (dest)
		then
		(OF) ← 1
		else
		(OF) ← 0
		else
		(OF) undefined

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-36