How to get device list from context in opencv

Question

I am developing a project using opencv and opencl. Right now, the kernels and the buffer runs using the opencv specified functions. For some reasons, I want to use OpenCL's native function instead of opencv function with least number of changes. I have two files. In the main file I created the context and pass it to the function to the second file. In the second file I need to build and execute kernel. If I would use OpenCV's function I can use execute kernel with the context that has been passed to the second file. But as I am planning to use OpenCL's native one, I need to bild the kernel and for that I need device list. My question is, is there any way I can get the device list from opencv created context? or how can I get the device list without passing the info from the main file?

Here is the snippet of main file:

  vector<ocl::Info> oclinfo;
  int devnums = ocl::getDevice(oclinfo);
  if( devnums < 1 )
    {
      std::cout << "no device found\n";
      return -1;
    }
  ocl::setBinpath("./");
  cv::ocl::Context* clCxt = ocl::Context::getContext();

ScanKernel( Mat& img,string kernelsrc,string kernelName,cv::ocl::Context* clCxt)

here is the code snippet of the second file:

const char * source    = kernelsrc.c_str();
size_t sourceSize[]    = { strlen(source) };


cpProgram = clCreateProgramWithSource((cl_context)clCxt->oclContext(), 1, &source, sourceSize, &ciErr1);
if (ciErr1 != CL_SUCCESS) {
printf("Error in clCreateProgramWithSource, Line %u in file %s %d !!!\n\n", __LINE__, __FILE__,ciErr1);

}
else
{       printf("*** Got createprogramwithsource\n");


**ciErr1 =  clBuildProgram(cpProgram, NULL, NULL, NULL, NULL, NULL);** 
if (ciErr1 != CL_SUCCESS) {
        printf("Error in building, Line %u in file %s error NO: %d!!!\n\n", __LINE__, __FILE__,ciErr1);

    }

I need help on getting the device list for clBuildProgram function.

Kyle Lutz Kyle Lutz · Accepted Answer · 2014-06-04T05:13:10

You can use the clGetContextInfo() function with the CL_CONTEXT_DEVICES argument to get a list of the devices associated with the context. Once you have the device list, you can pass it to clBuildProgram() to compile your program.

See the documentation here: http://www.khronos.org/registry/cl/sdk/1.0/docs/man/xhtml/clGetContextInfo.html

How to get device list from context in opencv

1 Answers