1.3.2 多字节无符号数乘法.txt

来自「《MCS-51单片机应用开发实用子程序》配套源代码」· 文本 代码 · 共 60 行

DOMUL:	
MOV	A,R1					
MOV	R6,A
MOV	A,R0					
MOV	R5,A					
MOV	A,R2					
ADD		A,R2					
MOV	26H,A
MOV	R7,A
MOV	A,R4
MOV	R0,A
CLEAR:		
MOV	@R0,#00H				
INC		R0					
DJNZ	R7,CLEAR
MOV	A,R4
MOV	R7,A
MOV	27H,R7
MOV	20H,R2
LP0:		
MOV	A,R5
MOV	R0,A
MOV	A,@R0
MOV	B,@R1
MUL		AB					
ACALL	ADDM
INC		R1
DJNZ	R2,LP0
MOV	R2,20H
MOV	A,R6
MOV	R1,A
MOV	A,R7
INC		A				
MOV	R7,A
MOV	R4,A
INC		R5
DJNZ	R3,LP0
MOV	R4,27H				
MOV	R5,26H
RET
ADDM:		
MOV	21H,A				
MOV	A,R4
MOV	R0,A
MOV	A,21H
ADD		A,@R0
MOV	@R0,A
MOV	A,B
INC		R0					
ADDC	A,@R0
MOV	@R0,A
INC		R0				
MOV	A,@R0
ADDC	A,#00H
MOV	@R0,A
DEC		R0					
MOV	A,R0
MOV	R4,A
RET