Assembly on Windows

Question

I am interested in doing minimal assembly programming on Windows. No GUI, just a plain old .exe program that will print a few characters to the console. In order to see if it was even possible to simply compile and run assembly on Windows, I tried the following:

test.s:

ret

command line:

gcc test.s

And I got the following error:

In function 'main': undefined reference to 'WinMain'

So the question is how do I go about compiling a simple assembly do-nothing program to a Windows executable? Do I need to define WinMain in every program? Is it a flag to gcc?

I don't really care which assembler I use, but if someone knows if this is the same of different for gcc(gas), masm and other assemblers, that would be nice, too.

you might want to start by looking at this question: http://stackoverflow.com/questions/1023593/how-to-write-hello-world-in-assembler-under-windows — PhiS, Jan 22 '14 at 17:37

James · Accepted Answer · 2014-01-23T02:15:33.453

You say you want pure or clean assembly, is this along those lines?

taken from The Assembly Programmers Master Book
language masm32 assembler,linker ml,link

source;

.586P
; Flat memory model
.MODEL FLAT, STDCALL
;---------------------------------------
; Data segment
_DATA SEGMENT

_DATA ENDS
; Code segment
_TEXT SEGMENT
START:
    RET  ; Exit
_TEXT ENDS
END START

assembly & linking;

ML /c /coff PROG1.ASM
LINK /SUBSYSTEM:WINDOWS PROG1.0BJ

This program was literally called "Do Nothing" but it is pure masm that just does nothing.

If you want to program in windows without the help of C you will have to program with the WIN32 api, you can find a reference to this api on the net called win.hlp win32.hlp, it would appear to be on this web-page

Perhaps a handy link -> MASM 6.1 Documentation

EDIT: Using as (gas) & ld;

.globl _start

_start: // ld looks for _start by default
    movl $22, %eax // AT&T syntax
    ret

compile;

c:\Users\James\Desktop\asm\>as file.s

c:\Users\James\Desktop\asm\>ld a.out

c:\Users\James\Desktop\asm\>a.exe

c:\Users\James\Desktop\asm\>echo %errorlevel%
22

Disassembly of section .text:

00401000 <_start>:
  401000:       b8 16 00 00 00          mov    $0x16,%eax
  401005:       c3                      ret
  401006:       90                      nop
  401007:       90                      nop

Simply putting ret is not going to get you far, you can get the assembly listings of your c/c++ programs by compiling with the -S flag (-masm=intel gives you intels syntax).

That said you need to specify an entry point for the linker to know where the code begins, you also need to create a text segment for the code, here is a really really simple example that returns 1;

    .text
    .intel_syntax noprefix
    .globl _main

_main: // entry point!
    mov eax, 1
    ret

gcc [file].s yeilds a.exe

Also, compiling with -S will give me assembly that needs to link with the C standard library. I want clean assembly — Baruch, Jan 22 '14 at 18:30
I don't know how you got errors, i just compiled that code on two different computers under both linux and windows??? — James, Jan 22 '14 at 19:00
I tried it on Windows and got that error. Which gcc are you using? — Baruch, Jan 22 '14 at 20:25
typing in `gcc --version` output `gcc (rev2, Built by MinGW-builds project) 4.8.1 Copyright (C) 2013 Free Software Foundation, Inc.`, ill edit in another way using `as` & `ld` — James, Jan 23 '14 at 02:07

Assembly on Windows

1 Answers1