8051 Program – check nth bit of a byte

; check nth bit of a byte
; data: 4000H
;result: 4001H
	ORG 0H
	DATA_ADDR EQU 4000H
	BIT_NO EQU 6	;0 to 7
MAIN:
	MOV DPTR,#DATA_ADDR	; fill memory
	MOV A, #55H
	MOVX @DPTR,A
	LCALL CHECK
	SJMP MAIN
CHECK:
	MOV DPTR, #MASK
	MOV A, #BIT_NO
	MOVC A,@A+DPTR
	MOV R7,A
	MOV DPTR,#DATA_ADDR
	MOVX A,@DPTR
	ANL A,R7
	MOV R7, #BIT_NO
	CJNE R7,#0,find
	SJMP store
find:	MOV R7, #BIT_NO
loop:	RR A
	DJNZ R7,loop
store:	INC DPTR	;increment dptr
	MOVX @DPTR,A	; move data from a to external memory location
return:
	RET
	ORG 300H
MASK:	DB 01H,02H,04H,08H,10H,20H,40H,80H
	END

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List of topics: 8051

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