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MICROPROCESSOR INSTRUCTION REFERENCE->BTST

BTST    Test a Bit

Compatibility: 68000, 68010, 68020, CPU32 families


Complement (<bit no.> Destination) -> Z

Assembler Syntax:	BTST Dn,<ea>
	BTST #<data>,<ea>

Dn or #<data> specify the bit no. and <ea> may be data only

Size:  Byte, Long


Tests a bit in the destination operand and sets the Z condition code appropriately.  When a data register is the destination, any of the 32 bits can be specified by a modulo 32-bit number.  When a memory location is the destination, the operation is a byte operation, and the bit number is modulo 8.  In all cases, bit zero refers to the leaset significant bit.

Condition Codes:

N    Not affected
Z    Set if bit tested = 0, else clear
V    Not affected
C    Not affected
X    Not affected

    

	Allowable Addressing Modes

	Dn,<ea>	#<data>,<ea>

	BTST	Dn,Dn	BTST	#(data),Dn
	BTST	Dn,(An)	BTST	#(data),(An)
	BTST	Dn,(An)+	BTST	#(data),(An)+
	BTST	Dn,-(An)	BTST	#(data),-(An)
	BTST	Dn,(d16,An)	BTST	#(data),(d16,An)
	BTST	Dn,(d8,An,Xn)	BTST	#(data),(d8,An,Xn)
	BTST	Dn,(bd,An,Xn) 2	BTST	#(data),(bd,An,Xn) 2
	BTST	Dn,([bd,An,Xn],od) 1	BTST	#(data),([bd,An,Xn],od) 1
	BTST	Dn,([bd,An],Xn,od) 1	BTST	#(data),([bd,An],Xn,od) 1
	BTST	Dn,(xxx).W	BTST	#(data),(xxx).W
	BTST	Dn,(xxx).L	BTST	#(data),(xxx).L
	BTST	Dn,#(data)
	BTST	Dn,(d16,PC)	BTST	#(data),(d16,PC)
	BTST	Dn,(d8,PC,Xn)	BTST	#(data),(d8,PC,Xn)
	BTST	Dn,(bd,PC,Xn) 2	BTST	#(data),(bd,PC,Xn) 2
	BTST	Dn,([bd,PC,Xn],od) 1	BTST	#(data),([bd,PC,Xn],od) 1
	BTST	Dn,([bd,PC],Xn,od) 1	BTST	#(data),([bd,PC],Xn,od) 1

Dn,Dn and #(data),Dn are long only; all others are byte only.

1   68020 only
2   68020 and CPU32 only