format ELF executable 3
entry start

segment readable executable

start:

  pushad
  mov ecx,[size]
  mov esi,[data]
  lea edi,[esi+ecx]
  xor eax,eax
  @@b:lodsb
     mov edx,eax
     mov ebx,eax
     and eax,7
     shr edx,3
     and edx,7
     shr ebx,6
     mov ah,byte[num+eax]
     mov al,byte[num+edx]
     shl eax,8
     mov al,byte[num+ebx]
     mov [edi],eax
     add edi,3
  loop @@b
  popad

segment readable writeable

num db '01234ABC',0xA
size db 1
data db 'ABC'    

const
  wct: array[0..7] of AnsiChar='ABCDEFGO';
var
  data:         array of byte;
  size:         Cardinal;
  input,output: file;
begin
  reset  (input,paramstr(1),1);
  rewrite(output,paramstr(2),1);
  size:=filesize(input);
  SetLength(data,size shl 2+1);
  BlockRead(input,data[0],size);
  close(input);
  asm
  pushad
  mov ecx,[size]
  mov esi,[data]
  lea edi,[esi+ecx]
  xor eax,eax
  @b:lodsb
     mov edx,eax
     mov ebx,eax
     and eax,7
     shr edx,3
     and edx,7
     shr ebx,6
     mov ah,byte[wct+eax]
     mov al,byte[wct+edx]
     shl eax,8
     mov al,byte[wct+ebx]
     mov [edi],eax
     add edi,3
  loop @b
  popad
  end;
  BlockWrite(output,data[size],size*3);
  close(output);
end.    

You don't have any return back to the OS when the code finishes, after the POPAD is executed.

Well, how i can realize that in linux assembly? Any examples?

MIHIP wrote:

Well, how i can realize that in linux assembly? Any examples?

Yes, of course. You need look no further than the example files included in the fasm linux download.

; fasm demonstration of writing simple ELF executable

format ELF executable 3
entry start

segment readable executable

start:

        mov     eax,4
        mov     ebx,1
        mov     ecx,msg
        mov     edx,msg_size
        int     0x80

        mov     eax,1
        xor     ebx,ebx
        int     0x80

segment readable writeable

msg db 'Hello world!',0xA
msg_size = $-msg    

format ELF executable 3
entry start

segment readable executable

start:

  pushad
  mov ecx,[size]
  mov esi,[dataz]
  lea edi,[esi+ecx]
  xor eax,eax
  @@b:lodsb
     mov edx,eax
     mov ebx,eax
     and eax,7
     shr edx,3
     and edx,7
     shr ebx,6
     mov ah,byte[num+eax]
     mov al,byte[num+edx]
     shl eax,8
     mov al,byte[num+ebx]
     mov [edi],eax
     add edi,3
  loop @@b
  popad

mov eax,4
mov ebx,1
mov ecx,[dataz]
mov edx,datasize
int 0x80

mov eax,1
xor ebx,ebx
int 0x80

segment readable writeable

num db '01234ABC'
size dd 1
dataz dd 'ABC',0xA
datasize = $-dataz    

gdb my_program
run
    

x/4i $eip
    

valgrind ./my_program