Samsung KS57C2308 manual Btsf Bit Test and Skip on False, LABEL2, LABEL3

KS57C2308/P2308/C2316/P2316SAM47 INSTRUCTION SET

BTSF — Bit Test and Skip on False

BTSF	dst.b
Operation:	Operand	Operation Summary	Bytes	Cycles
	DA.b	Test specified memory bit and skip if bit equals "0"	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 a "0", the BTSF instruction skips the instruction which immediately follows it; otherwise the instruction following the BTSF is executed. The destination bit value is not affected.

Operand				Binary Code						Operation Notation
DA.b	1	1	b1		b0	0	0	1	0	Skip if DA.b = 0
	a7	a6	a5		a4	a3	a2	a1	a0
mema.b *	1	1	1		1	1	0	0	0	Skip if mema.b = 0
memb.@L	1	1	1		1	1	0	0	0	Skip if [memb.7–2 + L.3-2].
										[L.1–0] = 0
	0	1	0		0	a5	a4	a3	a2
@H + DA.b	1	1	1		1	1	0	0	0	Skip if [H + DA.3–0].b = 0
	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 cause the program to continue execution from the instruction identified as LABEL2:

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

2. You can use BTSF in the same way to test a port pin address bit:

BTSF	P2.0	;	If P2.0	= "0", then skip
RET		;	If P2.0	= "1", then return
JP	LABEL3

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