How to write hello world in assembler under Windows?

feiroox picture feiroox · Jun 21, 2009 · Viewed 166.7k times · Source

I wanted to write something basic in assembly under Windows, I'm using NASM, but I can't get anything working.

How to write and compile hello world without the help of C functions on Windows?

Answer

caffiend picture caffiend · Jun 22, 2009

This example shows how to go directly to the Windows API and not link in the C Standard Library.

    global _main
    extern  _GetStdHandle@4
    extern  _WriteFile@20
    extern  _ExitProcess@4

    section .text
_main:
    ; DWORD  bytes;    
    mov     ebp, esp
    sub     esp, 4

    ; hStdOut = GetstdHandle( STD_OUTPUT_HANDLE)
    push    -11
    call    _GetStdHandle@4
    mov     ebx, eax    

    ; WriteFile( hstdOut, message, length(message), &bytes, 0);
    push    0
    lea     eax, [ebp-4]
    push    eax
    push    (message_end - message)
    push    message
    push    ebx
    call    _WriteFile@20

    ; ExitProcess(0)
    push    0
    call    _ExitProcess@4

    ; never here
    hlt
message:
    db      'Hello, World', 10
message_end:

To compile, you'll need NASM and LINK.EXE (from Visual studio Standard Edition)

   nasm -fwin32 hello.asm
   link /subsystem:console /nodefaultlib /entry:main hello.obj