Test if any OpenCL GPU device is available.

testSeeEl.c

//
//  main.cpp
//  testSeeEl
//
//  Created by Kim on 21/07/2013.
//  Copyright (c) 2013 Kim. All rights reserved.
//
//
//  clang -framework OpenCL -o testSeeEl testSeeEl.c && ./testSeeEl
//
#include <stdio.h>
#include <OpenCL/OpenCL.h>

int main(int argc, const char * argv[])
{
    cl_int errNum;
    cl_uint numPlatforms;
    cl_platform_id *platformIds;
    // First, query the total number of platforms
    errNum = clGetPlatformIDs(0, NULL, &numPlatforms);
    if (errNum != CL_SUCCESS || numPlatforms <= 0)
    {
        printf("Failed to find any OpenCL platforms.\n");
        return 1;
    }
    
    platformIds = (cl_platform_id *)alloca(sizeof(cl_platform_id) * numPlatforms);
    errNum = clGetPlatformIDs(numPlatforms, platformIds, NULL);
    if (errNum != CL_SUCCESS)
    {
        printf("Failed to find any OpenCL platforms.\n");
        return 1;
    }

    for (cl_uint i = 0; i < numPlatforms; i++)
    {
        cl_uint numDevices;
        // CL_DEVICE_TYPE_GPU will fail if none, so se if we can get all first
        errNum = clGetDeviceIDs(platformIds[i], CL_DEVICE_TYPE_ALL, 0, NULL, &numDevices);
        if (errNum != CL_SUCCESS)
        {
            printf("Failed to get device info\n");
            return 1;
        }
        // will fail if 0
        errNum = clGetDeviceIDs(platformIds[i], CL_DEVICE_TYPE_GPU, 0, NULL, &numDevices);
        if (errNum != CL_SUCCESS || numDevices < 1)
        {
            printf("No GPU device found for platform\n");
            return 0;
        }
        printf("%d GPU device(s) found\n", numDevices);
        
    }
    
    return 0;
}