Question

您好我想在emu8086中制作从屏幕输入的两个数字相加的程序，我喜欢程序结束后继续的程序我调用程序sumUp并且它做得很好但是在程序中退出之后程序完成..我希望程序继续下面的代码调用sumUp 非常感谢你

; multi-segment executable file template.

data segment
   message1 db "Enter 2 number..$"

   num1 db 0
   num2 db 0           
   suma dw 0

ends

stack segment
    dw   128  dup(0)
ends

code segment   

    sumUp proc

      pop bx
      pop ax 
      sub ax,30h

      mov suma,ax
      pop ax    
      sub ax,30h
      add suma,ax

    ret
    sumUP endp


start:
; set segment registers:
    mov ax, data
    mov ds, ax
    mov es, ax

; add your code here

    lea dx,message1
    mov ah,09h
    int 21h

    mov ah,1h
    int 21h

    mov num1,al

    mov ah,1h
    int 21h

    mov num2,al

    mov dh,0d
    mov dl,num1
    push dx

    mov dh,0d
    mov dl,num2
    push dx

    call sumUp      
    //I want the program to continue here after procedure is finished

    **mov cx,0**



ends

end start ; set entry point and stop the assembler.

Answer 1

您正在弄乱堆栈上的返回地址，因此当ret想要将其弹出（IP时）时它就不存在了。

不是弹出来访问堆栈上的数据，而是将bp设置为帧指针，这样就可以使用它作为基址寄存器来访问堆栈内存。

您必须保存/恢复来电者bp;通常使用push / pop，但在这种情况下，我们可以将其隐藏在cx（您不必保存/恢复）中，因为该功能很简单，并且不需要多个临时寄存器。

 ; multi-segment executable file template.

data segment
   message1 db "Enter 2 number..$"
ends

stack segment
    dw   128  dup(0)
ends

code segment   

    ; inputs: first arg in AX, 2nd arg on the stack
    ; clobbers: CX
    ; returns in: AX
    sumUp proc

      mov cx, bp       ; save caller's BP
      mov bp, sp
      mov ax, ss:[bp+2] ; get the value of pushed parameter without messing with top of the stack          
      mov bp, cx       ; restore it.

      ret  

    sumUP endp

start:
; set segment registers:
    mov ax, data
    mov ds, ax
    mov es, ax

; add your code here

    lea dx,message1
    mov ah,09h
    int 21h

    mov ah,1h
    int 21h        

    mov ah, 0
    sub al, 30h

    push ax

    mov ah,1h
    int 21h

    mov ah, 0
    sub al, 30h 
    ; no need to push second operand because its already in ax 
    call sumUp                               

    ; result in ax

    mov ah, 04ch
    int 21h  

ends

end start ; set entry point and stop the assembler.

Answer 2

需要添加

push bx：

code segment

    sumUp proc

      pop bx
      pop ax
      sub ax, 30h

      mov suma, ax
      pop ax
      sub ax, 30h
      add suma, ax

      push bx ; needs to be added here
    ret
    sumUP endp

程序完成后为什么程序没有继续（emu8086）？

2 个答案: