2.3.3双字节有符号数乘法.txt

MCS－51单片机应用开发实用子程序.rar

MULS: 
MOV 	R4,#0 			
MOV 	R5,#0
LCALL 	MDS 
MDS:	
CLR	F0					
MOV	A,R6					
JNB	ACC.7,MDS1			
CPL	F0					
XCH	A,R7					
CPL	A
ADD	A,#1
XCH	A,R7
CPL	A
ADDC	A,#0
MOV	R6,A
MULD: 						
MOV 	A,R3 				
MOV 	B,R7 
MUL 	AB 
MOV 	R4,B 				
MOV 	R5,A 
MOV	A,R3 				
MOV 	B,R6 
MUL 	AB 
ADD 	A,R4 				
MOV 	R4,A 
CLR 	A 
ADDC 	A,B 
MOV 	R3,A 
MOV 	A,R2 				
MOV 	B,R7 
MUL 	AB 
ADD 	A,R4 				
MOV 	R4,A 
MOV 	A,R3 
ADDC 	A,B 
MOV 	R3,A 
CLR 	A 
RLC 	A 
XCH 	A,R2 				
MOV 	B,R6 
MUL 	AB 
ADD 	A,R3 				
MOV 	R3,A 
MOV 	A,R2 
ADDC 	A,B 
MOV 	R2,A 
JB	F0,MDS2				
MDS2:	
MOV	A,R5					
CPL	A
ADD	A,#1
MOV	R5,A
MOV	A,R4
CPL	A
ADDC	A,#0
MOV	R4,A
MOV	A,R3
CPL	A
ADDC	A,#0
MOV	R3,A
MOV	A,R2
CPL	A
ADDC	A,#0
MOV	R2,A
CLR	OV						
RET