8bitmcu24div.asm

8位单片机（如51）实现24位除法汇编程序

;单字节无符号除法程序 (R2R3R4/R7)=(R2)R3R4 余数R7
;入口    :R2,R3,R4,R7
;占用资源:ACC,B,F0
;堆栈需求:3字节
;出口    :(R2),R3,R4,R7,OV
NDIV31   :mov  r2,#0ffH
          mov  r3,#20H
          mov  r4,#12H
          mov  r7,#05H
         
          MOV    A,R2
          MOV    B,R7
          DIV    AB
          PUSH   A
          MOV    R2,B
          MOV    B,#10H
NDV311   :CLR    C
          MOV    A,R4
          RLC    A
          MOV    R4,A
          MOV    A,R3
          RLC    A
          MOV    R3,A
          MOV    A,R2
          RLC    A
          MOV    R2,A
          MOV    F0,C
          CLR    C
          SUBB   A,R7
          JB     F0,NDV312
          JC     NDV313
NDV312   :MOV    R2,A
          INC    R4
NDV313   :DJNZ   B,NDV311
          POP    A
          CLR    OV
          JZ     NDV314
          SETB   OV
NDV314   :XCH    A,R2
          MOV    R7,A
          jmp  $