Question

I want to print the current working directory and its content. The program will be done in x86, 16bit Intel syntax, DOS Assembly using interrupts. The assembler I will use will be Turbo assembler. Here is my code so far(not much):

ASSUME  cs:code,    ds:data
data segment
buffer  db  64  dup  (0) ; buffer for the current directory name
data ends
code segment
start:
mov     ax,     data ;
mov     ds,     ax   ; move data segment into ds, es registers
mov     es,     ax   ;

mov     dl,     0             ; default drive 
mov     si,     offset buffer ; put current directory in buffer
mov     ah,     47h  ; GET CURRENT DIRECTORY
int     21h                  

; appending '$' to buffer end
    ; search until 0 found
mov     cx,     64  ; search over all buffer 
cld                                 ; starting from the beginning  
    end_string:                         
lodsb                               ; get current byte in al register
cmp     al,     0   ; compare it with 0
jne     continue                    ; if not equal jump to continue label
mov     al,     36  ; if equal copy 36('$' - ASCII) in al
mov     di,     si  ; set destination index to source index
sub     di,     1           ; decrement di 
stosb                               ; store in es:di the value contained in al
mov     cx,     1   ; stop looping by setting cx to 1
    continue: 
    loop end_string
    ; print string obtained 
mov     dx,     offset buffer  ; ds:dx - string start
mov     ah,     09h            ; WRITE STRING TO STANDARD OUTPUT
int     21h

mov     ax,     4c00h          ; end program with exit code 0
int     21h
    code ends
    end start   

I managed to get it running and display the current working directory. But now I don’t know how to get his child directories and the files contained in the directory. So my question is : how do I get them?

Answer 1

Use the DOS services FindFirst (0x4e) and FindNext (0x4f) to get a list of entries in the given directory. You can then differentiate subdirectories and files based on the returned attributes.