Intel 80C186XL, 80C188XL user manual Scan String When Source Operand is a Byte, Scas dest-string

INSTRUCTION SET DESCRIPTIONS

Table C-4. Instruction Set (Continued)

Name	Description	Operation	Flags
			Affected
SCAS	Scan String:	When Source Operand is a Byte:	AF
	SCAS dest-string	(AL) – (byte-string)	CF
			DF –
	Subtracts the destination string	if
			IF –
		(DF) = 0
	element (byte or word) addressed by
			OF
		then
	DI from the content of AL (byte string)
			PF
		(DI) ← (DI) + DELTA
	or AX (word string) and updates the
			SF
		else
	flags, but does not alter the destination
			TF –
		(DI) ← (DI) – DELTA
	string or the accumulator. SCAS also
			ZF ¸
		When Source Operand is a Word:
	updates DI to point to the next string
	element and AF, CF, OF, PF, SF and	(AX) – (word-string)
	ZF to reflect the relationship of the
		if
	scan value in AL/AX to the string
		(DF) = 0
	element. If SCAS is prefixed with
		then
	REPE or REPZ, the operation is
		(DI) ← (DI) + DELTA
	interpreted as "scan while not end-of-
		else
	string (CX not 0) and string-element =
		(DI) ← (DI) – DELTA
	scan-value (ZF = 1)." This form may be
	used to scan for departure from a
	given value. If SCAS is prefixed with
	REPNE or REPNZ, the operation is
	interpreted as "scan while not end-of-
	string (CX not 0) and string-element is
	not equal to scan-value (ZF = 0)."
	Instruction Operands:
	SCAS dest-string
	SCAS (repeat) dest-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-42