dlls with fasm

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panos90

Joined: 05 Apr 2012
Posts: 3
Location: Greece

panos90 18 Dec 2012, 16:08

Hello, i have created a dll that contains one function named "testing", using visual studio 2012.

Function "testing" does only one thing, just returns number 2

I am trying to use this dll with fasm, by doing this

Code:

library DllTest,'D:\ASM\DllTest.dll'
import DllTest,testing,'testing'

or even this

Code:

library DllTest,'D:\ASM\DllTest.dll'
import DllTest,testing,1

Fasm compiles fine
but every time i use the name "testing" inside my code, i get an error when the program executes, even if i dont call the function. For example, the following codes will produce an error

Code:

.data
msg db 'Number is:%d',10,0

.code
start:
        mov eax,5
        push eax
        push msg
        call [printf]

        call [getch]
        push 0
        call [ExitProcess]
        call [testing]

.end start

Code:

.data
msg db 'Number is:%d',10,0

.code
start:

        call [testing]
        push eax
        push msg
        call [printf]

        call [getch]
        push 0
        call [ExitProcess]

.end start

Code:

.data
msg db 'Number is:%d',10,0

.code
start:

        mov eax,testing
        push eax
        push msg
        call [printf]

        call [getch]
        push 0
        call [ExitProcess]

.end start

The error is "The application was unable to start correctly (0x000007b)"

Can anyone help me ? I just want to call function "testing" from fasm

18 Dec 2012, 16:08

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 18 Dec 2012, 16:13

Try copying the DLL to the same folder your executable is at, modify your fasm source to refer the dll just by its filename rather than the full path. If there are still problems, please upload your DLL (the binary, the source is only optional).

18 Dec 2012, 16:13

nmake

Joined: 13 Sep 2012
Posts: 192

nmake 18 Dec 2012, 16:23

printf uses c calling convention, you are not correcting the stack. You should use cinvoke for cdecl convention, even though it should still work, it is not good practice Very Happy

You must also verify that the dll uses cdecl or stdcall (or fastcall for that matter)

You can also correct the stack manually, after printf, put add esp,8

18 Dec 2012, 16:23

panos90

Joined: 05 Apr 2012
Posts: 3
Location: Greece

panos90 18 Dec 2012, 16:34

Thanks for the fast replies.
@nmake
Oops sorry , i missed that, but it does not fix the problem.

@LocoDelAssembly
I just tried that, still the problem remains

Here is the dll

Description:		Download
Filename:	DLLTest.rar
Filesize:	52.07 KB
Downloaded:	357 Time(s)

18 Dec 2012, 16:34

nmake

Joined: 13 Sep 2012
Posts: 192

nmake 18 Dec 2012, 16:38

18 Dec 2012, 16:38

nmake

Joined: 13 Sep 2012
Posts: 192

nmake 18 Dec 2012, 16:41

Your dll does not export any function.

If you make a .def(inition) file and store this inside of it

Code:

LIBRARY MyLibrary
EXPORTS FunctionName @1 <- Ordinal here

18 Dec 2012, 16:41

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 18 Dec 2012, 16:47

nmake is correct, no function is exported. Have you done this? (Or whatever is necessary, I've never made a DLL in VS actually)

18 Dec 2012, 16:47

panos90

Joined: 05 Apr 2012
Posts: 3
Location: Greece

panos90 18 Dec 2012, 17:09

I have followed a tutorial to make my dll.
Just tried what msdn says, and it worked fine. Thank you Smile

18 Dec 2012, 17:09

shutdownall

Joined: 02 Apr 2010
Posts: 517
Location: Munich

shutdownall 18 Dec 2012, 20:12

Never forget the examples section on flatassembler.
There is a working example of creating a DLL.
http://flatassembler.net/examples.php

18 Dec 2012, 20:12

DOS386

Joined: 08 Dec 2006
Posts: 1903

DOS386 20 Dec 2012, 01:47

Another one: http://board.flatassembler.net/topic.php?t=11170

20 Dec 2012, 01:47

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