importing from an unmanaged DLL

[Nkolsen]

Hi

I know this issue have been here before, but im struggeling with my problem.
Im trying to import an unmanaged DLL from C to C#.

From the headerfile i have the following declaration:

extern "C"_declspec(dl lexport)
long _stdcall TCatIoGetInputP tr( unsigned short nPort, void** ppInput, int nSize );

with the following variable description:

ppInp:
Address of the pointer to get the address of the output buffer. If TCatIoGetInputP tr succeeds, the pointer is initialized to the address of the input buffer.



I thought i could use something like:

[DllImport("TCat IoDrv.dll", SetLastError = true)]
public static extern int TCatIoGetInputP tr(ushort nPort, byte [] ppInput,
int nSize);

But it doesnt seem to work.


Any one who could help ?


Thanks,

Nikolaj

[Plater]

Do you have .def file in your unmanaged DLL?

I have one for my "TestFixtureDLL .dll" that looks something like this:

; TestFixtureDLL.def : Declares the module parameters for the DLL.

LIBRARY      "TestFixtureDLL"

EXPORTS
    ; Explicit exports can go here
	DllCanUnloadNow     PRIVATE
	DllGetClassObject   PRIVATE
	DllRegisterServer   PRIVATE
	DllUnregisterServer PRIVATE
	writelocalbus
	readlocalbus
	swritelocalbus
	sreadlocalbus

The four functions I want available to managed code were:
writelocalbus
readlocalbus
swritelocalbus
sreadlocalbus
NOTE: That is not their function defs, for instance writelocalbus is really:

bool writelocalbus(UINT16 Offset, UINT16 Data)
{
//....
}

The other four functions were required by the DLL to be used in managed code (I think, maybe they are just general DLL requirements)

[Nkolsen]

I only have the header file for the function calls, so im not able to see what is in the .DLL.

My problem is what to do with the double void pointer in C# ? Can I just use a bytearray?

[Plater]

My problem is what to do with the double void pointer in C# ? Can I just use a bytearray?

I didn't even see that void **, you might ahve to read into the Marshalling section in MSDN about what to do with void **. This goes beyond my realm of unamanged DLL usage.

[Nkolsen]

Yea have been there looking for solutions, but cant find much specifically about my issue..

[Plater]

Have you tried using IntPrtr for void** ?