ch18_外部数据存储器做整段值的比较.asm

51单片机基础篇 对于有一定基础的人看看 包含书中所以的源代码

     ;FUNCTION NAME: EXTERNAL_DATA_COMPARE
     ;FUNCTION: COMPARE 2 BLOCKS EXTERNAL DATA MEMORY(R2)TIMES
     ;BLOCK 1 START AT DPTR
     ;BLOCK 2 START AT R7,R6
     ;
     EXTERNAL_DATA_COMPARE
     $1   	MOVX 	A,@DPTR
           	MOV   	B,A       	;BLOCK 1 DATA IN B
           	PUSH  	DPH  
           	PUSH  	DPL
           	MOV   	DPH,R7
           	MOV   	DPL,R6
           	MOVX  	A,@DPTR  	;BLOCK 2 DATA IN A
           	INC   	DPTR
           	MOV   	R7,DPH
           	MOV   	R6,DPL   	;BLOCK 2 INDEX+1
           	POP   	DPL
           	POP   	DPH
           	INC   	DPTR     	;BLOCK 1 INDEX+1
           	CJNE  	A,B,$2   	;COMPARE 1 BYTE
           	DJNZ  	R2,$1
           	MOV   	A,#00H    	;NO ERROR
           	SJMP  	$2+2
     $2       MOV   	A,#01H    	;ERROR
           	RET
     ;