dll questions..

Index > Windows > dll questions..

Author

Thread

windwakr

Joined: 30 Jun 2004
Posts: 827

windwakr 30 Jun 2004, 23:19

Im pretty new to assembly and I have a couple of dll questions. I wanna make dlls for a program called Gamemaker but gamemaker only reads doubles. EX dev-c++ code:

Code:

#define export extern "C" __declspec( dllexport )
export double add(double n1, double n2)
{
return n1+n2;
}

can you export doubles in FASM?
O, and one more question.
when i do invoke something like getsyscolor
how do I put that in a var?

btw: My first post here!

_________________
----> * <---- My star, won HERE

30 Jun 2004, 23:19

pelaillo
Missing in inaction

Joined: 19 Jun 2003
Posts: 878
Location: Colombia

pelaillo 30 Jun 2004, 23:38

Welcome windwakr,

"double" in this case is an integer type with 32 bit size. What does it mean is that you get two 32bit values and return one.
In assembly the type of the values is given by the size. A 32 bit value is called a DoubleWord or dword.
One of the characteristics of win32 in 32 bit processors is that you wrtie faster and simpler programs if the values passed to functions and returned from them are dword values.

The procedure in Fasm will look like:

Code:

proc add,n1,n2
    enter
    mov eax,[n1]
    add eax,[n2]
    return
endp

For the rest of the code for the dll, give a look at
http://board.flatassembler.net/topic.php?t=1760

30 Jun 2004, 23:38

pelaillo
Missing in inaction

Joined: 19 Jun 2003
Posts: 878
Location: Colombia

pelaillo 30 Jun 2004, 23:58

Quote:

when i do invoke something like getsyscolor
how do I put that in a var?

The returned value is in eax, so here is an example using a local variable (local variables exists only within procedures, because they are located on stack)

Code:

proc WinProc,hwnd,wmsg,wparam,lparam
  .background_brush dd ?
        enter
       push    ebx esi edi
 mov     eax,[wmsg]
  cmp     eax,WM_CREATE
       je      .wm_create
  .defwndproc:
    invoke DefWindowProc,[hwnd],[wmsg],[wparam],[lparam]
        jmp     .finish
  .wm_create:
        invoke GetSysColor,COLOR_WINDOW
     mov     [.background_brush],eax
  .finish:
   pop     edi esi ebx
 return
endp

30 Jun 2004, 23:58

VitalOne

Joined: 29 Jul 2003
Posts: 54
Location: USA

VitalOne 01 Jul 2004, 02:40

Hi, I use to use Game Maker (as VitalDragon, made the download DLL) and made other DLLs using FASM for Game Maker. You have to use FPU Instructions for GM (for some reason...) which are documented in the FASM PDF.

Code:

format PE GUI 4.0 DLL
entry DllEntryPoint

include '%fasminc%\win32a.inc'

section '.data' data readable writeable
ans dq 0

section '.code' code readable executable

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

proc add_asm,arg1,arg1a,arg2,arg2a
     fld [ans]
     fld qword [arg1]
     fadd qword [arg2]
     return
endp

section '.idata' import data readable writeable

  library kernel,"KERNEL32.DLL"

  import kernel,\
         GetProcAddress,"GetProcAddress"

section '.edata' export data readable

  export 'add.dll',\
         add_asm,"add_asm"

section '.reloc' fixups data discardable

That's a simple example that adds two numbers. Since doubles are 64-bit, one double argument is two 32-bit arguments, (hence arg1,arg1a).

Also if the DLL is less than 3.5KB Game Maker displays an error (?)...

01 Jul 2004, 02:40

windwakr

Joined: 30 Jun 2004
Posts: 827

windwakr 01 Jul 2004, 14:59

ok thanks for all the information!

btw:You were vitaldragon?

01 Jul 2004, 14:59

VitalOne

Joined: 29 Jul 2003
Posts: 54
Location: USA

VitalOne 02 Jul 2004, 02:52

windwakr wrote:

ok thanks for all the information!

btw:You were vitaldragon?

Yeah...I don't use that program much anymore though

02 Jul 2004, 02:52

< Last Thread | Next Thread >

Forum Rules:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum