多字节除法.asm

4字节以下除以两个字节（站长帮帮忙

;*********************************
;**  东华理工大学电子与机械工程学院
;**         3  +  1  班
;**            06届
;**     http://www.ecit.edu.cn
;**-------------------------------                             
;**项目名称:    多字节除法 
;**创   建   人:        张佳平 
;**描        述:     实现16进制2～4个字节
;       除以2个字节的计算。但由于程序本身缺
;      陷，除数必须是两个字节的16进制数。  
;*********************************
        
        MOV     30H,#01H        ;除数低字节
        MOV     31H,#01H        ;除数高字节
        MOV     32H,#02H        ;被除数低字节
        MOV     33H,#02H        ;被除数次低字节
        MOV     34H,#00H        ;被除数高字节
        MOV     40H,#00H
        MOV     41H,#00H
        MOV     20H,#00H        ;存放余数低字节
        MOV     21H,#00H        ;存放余数高字节
        MOV     22H,#00H        ;存放商值
        MOV     R7,#24
        MOV     R6,#0 
  
        
     ;被除数前面添加与除数位数相等的且均为0的字节   
RLEFT:  CLR	C
        MOV     A,32H
        RLC	A
        MOV     32H,A
        MOV     A,33H
        RLC	A
        MOV     33H,A
        MOV     A,34H
        RLC	A
        MOV     34H,A
        MOV     A,40H
        RLC	A
        MOV     40H,A
        MOV     A,41H
        RLC	A
        MOV     41H,A
        
       
       ;用减法比较被除数与除数大小      
       MOV      A,41H
       SUBB     A,31H
       JNC      ADD1            ;进位为0，说明被除数大于等于除数，跳转到商加1程序
       MOV      A,R6
       RL       A
       MOV      R6,A
       DJNZ     R7,RLEFT      
       LJMP     ENDD

       
ADD1:  MOV     R2,41H
       CJNE    R2,#0,ADD11
       LJMP    RLEFT
ADD11: MOV     41H,A
       MOV     A,R6
       RL      A
       MOV     R6,A
       INC     R6     
       MOV     A,40H
       SUBB    A,30H
       JNC     LOOP
       MOV     40H,A
       DEC     41H
       DJNZ     R7,RLEFT
       LJMP    ENDD
        
        
LOOP:   MOV     40H,A
        DJNZ    R7,RLEFT
        LJMP    ENDD        
        
ENDD:   MOV     22H,R6
        MOV     21H,41H
        MOV     20H,40H
        NOP
        END