3.2.3多字节减法.txt

数值算法,C51单片机的汇编程序

MBCDB:
LCALL 	NEG1 			
LCALL 	MBCDADD 		 
CPL 	C 				
MOV 	F0,C 			
LCALL 	NEG1 			
MOV 	C,F0 			
RET 
NEG1: 
MOV 	A,R0 			
XCH 	A,R1 			
XCH 	A,R0 
LCALL 	NEG 			
MOV 	A,R0 
XCH 	A,R1 		
XCH 	A,R0 
RET 
BCDSB:
CLR 	F0				
MOV 	R0,#7
ACALL 	NEG3			
JC  	BSBRT		
MOV 	A,R4				
ADD 	A,R7
DA  	A
MOV 	R4,A
MOV 	A,R3
ADDC 	A,R6
DA  	A
MOV 	R3,A
MOV 	A,R2
ADDC 	A,R5
DA  	A
MOV 	R2,A
JC  	BSBRT			
MOV  	R0,#4
SETB 	F0
NEG3:
MOV 	R1,#3			
CLR  	C
NGLP0:
MOV 	A,#99H			
SUBB  	A,@R0
MOV   	@R0,A
DEC   	R0
DJNZ  	R1,NGLP0			
INC   	R0
INC   	R0
INC   	R0
MOV  	R1,#3
SETB 	C				
NGLP1:
CLR 	A
ADDC 	A,@R0
DA   	A
MOV  	@R0,A
DEC  	R0
DJNZ 	R1,NGLP1
BSBRT:
RET