2.3.4多字节有符号数乘法.txt

来自「《MCS-51单片机应用开发实用子程序》配套的源代码」· 文本 代码 · 共 83 行

FMUL: 
LCALL 	MVR0 			 
MOV 	A,@R0 
XRL 	A,@R1 			
RLC 	A 
MOV 	1FH,C 			
LCALL 	MUL0 			
LJMP 	MOV0 			 
MUL0: 
LCALL 	MVR1 			 
MUL1: 
MOV 	A,R3 			
ORL 	A,R4 
JZ 		MUL6 
MOV 	A,R6 			
ORL 	A,R7 
JZ 		MUL5 
MOV 	A,R7 			
MOV 	B,R4 
MUL 	AB 
MOV 	A,B 
XCH 	A,R7 
MOV 	B,R3 
MUL 	AB 
ADD		A,R7 
MOV 	R7,A 
CLR 	A 
ADDC 	A,B 
XCH 	A,R4 
MOV 	B,R6 
MUL 	AB 
ADD 	A,R7 
MOV 	R7,A 
MOV 	A,B 
ADDC 	A,R4 
MOV 	R4,A 
CLR 	A 
RLC 	A 
XCH 	A,R3 
MOV 	B,R6 
MUL 	AB 
ADD 	A,R4 
MOV 	R4,A 
MOV 	A,B 
ADDC 	A,R3 
MOV 	R3,A 
JB 		ACC.7,MUL2		
MOV 	A,R7 			
RLC 	A 
MOV 	R7,A 
LCALL 	RL1 
MUL2: 
MOV 	A,R7 
JNB 		ACC.7,MUL3 
INC 		R4 
MOV 	A,R4 
JNZ 		MUL3 
INC 		R3 
MOV 	A,R3 
JNZ 		MUL3 
MOV 	R3,#80H 
INC 		R2 
MUL3:
MOV 	A,R2 			 
ADD 	A,R5 
MD: 
MOV 	R2,A 			
JB 		ACC.7,MUL4 
JNB 		ACC.6,MUL6 
MOV 	R2,#3FH 			
SETB 	OV 
RET 
MUL4: 
JB 		ACC.6,MUL6 
MUL5: 
CLR 	A 				
MOV 	R3,A 
MOV 	R4,A 
MOV 	R2,#41H 
MUL6:
CLR 	OV 
RET