Samsung KS57C2308 manual Btst Bit Test and Skip on True

KS57C2308/P2308/C2316/P2316 SAM47 INSTRUCTION SET

BTST — Bit Test and Skip on True

BTST	dst.b
Operation:	Operand	Operation Summary	Bytes	Cycles
	C	Test carry bit and skip if set (= "1")	1	1 + S
	DA.b	Test specified bit and skip if memory bit is set	2	2 + S
	mema.b		2	2 + S
	memb.@L		2	2 + S
	@H+DA.b		2	2 + S

Description: The specified bit within the destination operand is tested. If it is "1", the instruction that immediately follows the BTST instruction is skipped; otherwise the instruction following the BTST instruction is executed. The destination bit value is not affected.

Operand				Binary Code						Operation Notation
C	1	1	0		1	0	1	1	1	Skip if C = 1
DA.b	1	1	b1		b0	0	0	1	1	Skip if DA.b = 1
	a7	a6	a5		a4	a3	a2	a1	a0
mema.b *	1	1	1		1	1	0	0	1	Skip if mema.b = 1
memb.@L	1	1	1		1	1	0	0	1	Skip if [memb.7–2 + L.3–2].
										[L.1–0] = 1
	0	1	0		0	a5	a4	a3	a2
@H+DA.b	1	1	1		1	1	0	0	1	Skip if [H + DA.3–0].b = 1
	0	0	b1		b0	a3	a2	a1	a0

				Second Byte						Bit Addresses
* mema.b
	1	0	b1		b0	a3	a2	a1	a0	FB0H–FBFH
	1	1	b1		b0	a3	a2	a1	a0	FF0H–FFFH

Examples: 1. If RAM bit location 30H.2 is set to “0”, the following instruction sequence will execute the RET instruction:

BTST	30H.2	;	If 30H.2 = "1", then skip
RET		;	If 30H.2 = "0", return
JP	LABEL2

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