CODEWITHSUNDEEP
assemblyx86-16file-managementemu8086
harmione
harmione

Reputation: 21

Why doesn't this assembly code delete the file with ".lnk" extension?

I am trying to delete a file that has ".lnk" extension using assembly 8086 architecture. When I write "jmp DELETE" after "mov si, dx" and skip the inner, back1, back2, back3 part, my code deletes all the file, but when it checks if it has .lnk extension character by character, it doesn't delete any of them, not even the file with .lnk extension . Why is it happening?

.MODEL SMALL
.STACK 100H
.DATA
FILE DB "*", 0
DTA DB 128H DUP(?)   
FILENAME DB 50 DUP(?)
.CODE

MAIN PROC  

    MOV AX,@DATA
    MOV DS,AX

    ;SET DTA
    MOV DX,OFFSET DTA
    MOV AH,1AH
    INT 21H

    ;FIRST SEARCH
    MOV DX,OFFSET FILE 
    MOV CX,0
    MOV AH,4EH
    INT 21H
    JC QUIT

OUTER_LOOP:


    ;DELETE
    LEA DX,DTA+30 
    mov si, dx 

    inner:
    cmp [si], 0
    je back1
    inc si
    jmp inner

    back1:
    dec si
    cmp [si],'K'
    je back2
    jmp NEXT

    back2:
    dec si
    cmp [si],'N'
    je back3
    jmp NEXT

    back3:

    dec si
    cmp [si], 'L'


    delete:
    LEA DX,DTA+30 
    MOV AH,41H
    INT 21H


    ;INITIATE NEXT SEARCH
    NEXT:
    MOV DX,OFFSET FILE 
    MOV CX,0
    MOV AH,4FH
    INT 21H
    JC QUIT

    JMP OUTER_LOOP



QUIT:
    MOV AX,4C00H
    INT 21H

MAIN ENDP
    END MAIN

Upvotes: 2

Views: 390

Answers (1)

Sep Roland
Sep Roland

Reputation: 39166

These points might interest you:

  • Change your filemask to 

    *.*

  • Why do you set up such a large DTA?.

    DTA 44 dup(?)

  • Always write cmp byte ptr [si], ...

  • Don't stop comparing after the 3 characters. Add a fourth compare to see if the point is present. Then you'll know that LNK is indeed a file extension.

  • Your 4Fh DOS call doesn't need the CX and DX parameters.

  • You don't interpret the result from

    cmp [si], 'L'

Upvotes: 2

Related Questions