CUDA dll functions

[Andreik]

Does anyone tried with success to compile a dll with a function that use CUDA and then to call the function from AutoIt? Actually the compilation seems to be easy but it might be a little hard to call the function. Here is what I have:

cuda.cu

#include <cuda.h>
#include <cuda_runtime.h>
#include <device_launch_parameters.h>


__global__ void cuda__add(int *a, int *b, int *c)
{
   *c = *a + *b;
}

extern "C" __declspec(dllexport) int Add(int a, int b)
{
  int c;
  int *dev_a,*dev_b,*dev_c;
  int size = sizeof(int);

  cudaMalloc((void**)&dev_a, size);
  cudaMalloc((void**)&dev_b, size);
  cudaMalloc((void**)&dev_c, size);

  cudaMemcpy(dev_a, &a,sizeof(int), cudaMemcpyHostToDevice);  
  cudaMemcpy(dev_b, &b,sizeof(int), cudaMemcpyHostToDevice);  

  cuda__add<<< 1,1 >>>(dev_a,dev_b,dev_c);
  cudaMemcpy(&c, dev_c,size, cudaMemcpyDeviceToHost);

  cudaFree(&dev_a);
  cudaFree(&dev_b);
  cudaFree(&dev_c);

  return c;
}

I am able to open the dll but the function is not visible somehow and I get error 3 when I call it from AutoIt.

[RTFC]

Hello Andreik,

I use CUDA myself, but in a pure C++ environment (need for speed). However, I do have some experience in integrating my own dlls in AutoIt. First off, there's a mismatch between your function declaration and the actual definition (first has 2 parameters, second 3).

My next reaction would be to check capitalisation in the dll call, as these function names are case-sensitive. Furthermore, can you get a non-CUDA dll function to work in the same code?

RT

[Andreik]

Hello RTFC,

Thanks for your answer but there's not any mismatch, first one is the function called on device (GPU) and the second one called on the host (CPU). I try to export the function called on the host and the problem isn't the capitalisation because a simple dumpbin.exe /EXPORTS cuda.dll shows me that there's not any exported function.

[RTFC]

Sorry, my mistake. So where do you actually declare your CPU function then? And what does that declaration look like?

AFAIK, to export your dll function(s), <yourdll>.h file should contain the declaration:

extern "C"
{

__declspec(dllexport) int Add(<params>);

}

and <yourdll>.cpp should contain the full definition:

#include <yourdll>.h

extern "C"
{

__declspec(dllexport) int Add(<params>)

{

<code>

}

}

That's just how I do it.

Edited June 15, 2015 by RTFC
addendum

[jchd]

A DLL without export nor externs seems pretty useless.

[RTFC]

@jchd: of course, that goes without saying. Added to pseudo-code example.