String buffer in assembly code

问题

I just have ended my code which allow to cover your password. It goes like this(FASM):

org 100h

mov cx, 16

petla:
mov ah,08h
int 21h
cmp al,0dh
je OK
mov ah,02h
mov dl,42
int 21h

cmp cx,0
je Fail
loop petla

Fail:

mov dl, 0ah
int 21h
mov dx, pass2
mov ah,9
int 21h
jmp koniec

OK:

mov dl, 0ah
int 21h
mov dx, pass
mov ah,9
int 21h
jmp koniec


koniec:
mov ah,4ch
int 21h

pass db 'Password OK', 0Ah, 0Dh, '$'
pass2 db 'Password Fail', 0Ah, 0Dh, '$'

And now I need to print the genuine password. I know the string buffer is a must and how declaration of the buffer should look like but I don't really know how to use it and make it work. Calling for help :) Cheers.

回答1:

Since your program allows the input of 15 characters of password, you could setup the buffer with:

Buffer db 16 dup ("$")

You initialize the DI register before your petla loop and put the ASCII code you got from the DOS function in the buffer via a stosb instruction:

  mov  di, Buffer
  mov  cx, 16
petla:
  mov  ah,08h
  int  21h
  cmp  al,0dh
  je   OK
  stosb
  mov  ah,02h
  mov  dl,42
  int  21h
  ;;;cmp cx,0
  ;;;je Fail
  loop petla

Please note that compairing for CX=0 is useless just before the loop instruction in your code.

来源：https://stackoverflow.com/questions/33948308/string-buffer-in-assembly-code