FASM DLL Problem

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Phosque

Joined: 20 May 2007
Posts: 2
Location: Sweden

Phosque 20 May 2007, 17:22

Hi!

I'm new around here, hopefully I'll stay Smile

I'm trying to create a DLL in FASM, exporting basic VGA functions. It compiles just fine, but when I run it from another programming language it doesn't work. Any help is greatly appreciated.

Code:

format PE GUI 4.0 DLL
entry DllEntryPoint

include '%fasminc%\win32a.inc'

section '.code' code readable executable

proc DllEntryPoint hinstDLL,fdwReason,lpvReserved
        mov eax,TRUE
        ret
endp

proc OpenScreen
    org 100h    ; DOS
    mov al, 13h ; VGA 320x200
    int 10h     ;
endp

proc SetPixel
     mov ax,0a000h
     mov ds,ax

     mov si,120    ; Position
     mov al,1      ; Color
     mov [si],al   ; Draw in vid mem
endp

section '.edata' export data readable

  export 'gfxlib.dll',\
         OpenScreen, 'OpenScreen'

section '.reloc' fixups data discardable

(Yes, I just modified the DLL example that came with FASM)

Thanks,
Martin

20 May 2007, 17:22

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 20 May 2007, 17:39

Code:

proc OpenScreen 
    org 100h    ; DOS 
    mov al, 13h ; VGA 320x200 
    int 10h     ; 
endp

As you said, it's for DOS and will not work under Windows. You have to use DirectDraw instead. Also note that "org 100h" is not a kind of DOS tag, it only sets the origin, something that could lead some problems when you write a DLL.

20 May 2007, 17:39

Phosque

Joined: 20 May 2007
Posts: 2
Location: Sweden

Phosque 20 May 2007, 18:05

Alright, thanks for the reply, LocoDelAssembly.

20 May 2007, 18:05

Hayden

Joined: 06 Oct 2005
Posts: 132

Hayden 21 May 2007, 03:46

to make things more clear for other readers, interrupt calls cannot be used in a window *.dll

_________________
New User.. Hayden McKay.

21 May 2007, 03:46

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 21 May 2007, 13:01

Although it's undocumented you can do it even on NT/2000/XP, look at NTDLL.DLL disassembly on machines with no SYSENTER/SYSCALL support. On http://www.ctyme.com/intr/cat-049.htm you can see interrupt services for non-NT Windowses.

What you can't do is calling BIOS** and DOS** interrupts from Windows.

**On Win9x I'm almost sure that I saw it on 16-bit or 32-bit Windows executables but Int $10 wasn't one of them.

21 May 2007, 13:01

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