[DOS vs Win64 FASM vs MASM] Error: Extra characters on line

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Hazique35

Joined: 01 Apr 2013
Posts: 7

Hazique35 02 Apr 2013, 15:02

Hello again, Ive been having this problem using OFFSET. i just wanted to display a string. So, is this allowed in fasm, and if not, then I should always use message box?

heres what Ive written:

Code:

include 'win64wxp.inc'

.data

message db "Hello, World!$"

.code

start:

mov dx,OFFSET message
mov ax, SEG message
mov ds, ax
mov ah, 9
int 21h

.end start

Anything I shouldnt be using?

02 Apr 2013, 15:02

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20299
Location: In your JS exploiting you and your system

revolution 02 Apr 2013, 15:11

A number of things here:

1) fasm doesn't use either OFFSET or SEG. Just delete them

2) You have included the Windows 64-bit header file but appear to be writing DOS code following it. That can't ever work.

Have a look at the WIN32 or WIN64 examples in the fasm download if you want to write a Windows program.

02 Apr 2013, 15:11

Hazique35

Joined: 01 Apr 2013
Posts: 7

Hazique35 02 Apr 2013, 15:16

Ok, so how do I start using DOS instead of using the windows header

02 Apr 2013, 15:16

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20299
Location: In your JS exploiting you and your system

revolution 02 Apr 2013, 15:28

There are also DOS example files in the fasm download. This is copied from "MULTISEG.ASM":

Code:

; fasm example of writing multi-segment EXE program

format MZ

entry main:start                        ; program entry point
stack 100h                              ; stack size

segment main                            ; main program segment

  start:
        mov     ax,text
        mov     ds,ax

        mov     dx,hello
        call    extra:write_text

        mov     ax,4C00h
        int     21h

segment text

  hello db 'Hello world!',24h

segment extra

  write_text:
        mov     ah,9
        int     21h
        retf

There are other examples also, like .com files etc.

02 Apr 2013, 15:28

Hazique35

Joined: 01 Apr 2013
Posts: 7

Hazique35 02 Apr 2013, 15:38

thanks. Sorry, I didnt see those example.

02 Apr 2013, 15:38

DOS386

Joined: 08 Dec 2006
Posts: 1900

DOS386 04 Apr 2013, 01:31

Hazique35 wrote:

Ok, so how do I start using DOS instead of using the windows header

1. Get DOS www.freedos.org www.drdos.org www.drdosprojects.de

2.Get DOS FASM http://flatassembler.net/download.php

3. Look at the examples included

4. Look into the DOS subforum and the FAQ on the top
http://board.flatassembler.net/forum.php?f=2 http://board.flatassembler.net/topic.php?t=9473

Hazique35 wrote:

I should always use message box?

If you want to support DOS: NO
If you want tom support Win64: YES

04 Apr 2013, 01:31

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