523.asm

本书为清华大学第二版汇编语言的课后题详解

;523.asm

        .model small
        .data
a       dw 7
b       dw 4
        .stack 100h
        .code
main    proc  far
start:
        push  ds
        sub   ax,ax
        push  ax
        mov   ax,@data
        mov   ds,ax
        mov   ax,a
        mov   bx,b
        mov   si,0
        mov   di,0
        mov   cx,0
        shr   ax,1
        jnc   next1
        inc   si
next1:  shr   bx,1
        jnc   next2
        inc   di
next2:  add   cx,si
        add   cx,di
        cmp   cx,1
        jz    n1
        cmp   cx,2
        jz    n2
        jmp   short n3exit
n1:     cmp   si,0
        jnz   n3exit
        mov   ax,b
        xchg  a,ax
        xchg  ax,b
        jmp   short n3exit
n2:     add   a,1
        add   b,1
        jmp   short  n3exit
n3exit: ret
main    endp
        end   start