How can i run a DLL?

BlitzMax Forums/BlitzMax Beginners Area/How can i run a DLL?

MrCredo

(Posted 2005) [#1]

i spended few days so start DYNAMICALY a user definded DLL

but this don't work each time..

download DLL
http://www.blitzbase.de/codes.zip

source:

Local dll :Int =LoadLibraryA("dummy.dll")
Local addr:Int =Int(GetProcAddress(dll,"test@8"))
Local func:Int (v1:Int, v2:Int)

(Int Ptr(Varptr(func)))[0]=addr

Print dll +" <dummy.dll"
Print addr+" <test@8"
Print func(3,4)
Print func(3,4)
Print func(3,4)
Print func(3,4)
Print func(3,4)
Print func(3,4)
Print func(3,4)
Print func(3,4)
Print func(3,4)
Print func(3,4)

on my machine - this program display a error message in debugmode after starting few times this function...

DredPirateRoberts

(Posted 2005) [#2]

I got it to work by making a c wrapper, just do something like this in a c file

#include "windows.h"

#define BBCALL _stdcall

const void BBCALL (*PGfxInit) ( void );

byte * DredGetProcAddress ( HINSTANCE lib, char * fname )
{
   byte * ptr;

   ptr =  GetProcAddress ( lib, fname );

   if ( ptr == NULL ) 
   {
       printf ("\nNULL: %s\n", fname );
       fflush(NULL);
   }

   return(ptr);
}

void DredInitDll ( void )
{
   HINSTANCE lib;

   lib = LoadLibraryA (TEXT("dred") );
   PGfxInit = DredGetProcAddress ( lib, "GfxInit@0");
}

// =========================
void GfxInit ( void )
{
   PGfxInit();
}

Then do the nessesary externs in bmx , import the c file in bmx.. call the dll init then the wrapper functions ( like GfxInit ). maybe there is another way ? but i couldnt get anything else to work.

MrCredo

(Posted 2005) [#3]

i don't understand...

DredPirateRoberts

(Posted 2005) [#4]

You just make function pointers in the c file . then make a real function in C that calls the function pointer to the dll .. call the C real function from blitzmax . It does work i been calling my own dll and the freeimage.dll routines no problems at all using it this way.

just make your c wrapper file like my post above and

Import "mycwrapper.c"

then make the externs for the wrapper functions . then just call them from bmax.

( if i get some more time. ill post a more detailed example )

MrCredo

(Posted 2005) [#5]

i cannot import source - this are 3rd party dll's or "plugins" with undefined dll-names... but every dll has equal function-names...

DredPirateRoberts

(Posted 2005) [#6]

You dont need the source to the dll ( if thats what u mean ? ). im using a 3rd party dll ( freeimage ). u just make function pointers in your own c file .. setup like in my example above. then make a C function that calls the Function Pointer . then import your c file into bmax and call your C function from bmx ( that calls the function thru the pointers that call the dll functions )

Sweenie

(Posted 2005) [#7]

I tried the method MrCredo used to call the GetTickCount function from the win32 API.
I didn't give me any errors, even then calling the function 100000 times in a row.
Could the problem lie within the dll perhaps?
What calling convention does your dll-function use?

Sweenie

(Posted 2005) [#8]

Ok, your dll use the standard calling convention.(Just checked your sourcecode)

Add "win32" to the end of your function declaration.
Like this...
Local func:Int (v1:Int, v2:Int) "win32"

that should take care of the problem.
I don't know which calling convention BMax uses by default but by adding "win32" you tell Bmax to use stdcall for this function.

Found this interesting article about calling conventions...
http://www.angelcode.com/dev/callconv/callconv.html

MrCredo

(Posted 2005) [#9]

I love you Sweenie... :-)