@c -*-texinfo-*-

@c This file is part of the StarPU Handbook.
@c Copyright (C) 2009-2011  Université de Bordeaux 1
@c Copyright (C) 2010, 2011  Centre National de la Recherche Scientifique
@c See the file starpu.texi for copying conditions.

@smallexample
#include <starpu.h>
#include <starpu_opencl.h>

extern struct starpu_opencl_program programs;

void scal_opencl_func(void *buffers[], void *_args)
@{
    float *factor = _args;
    int id, devid, err;
    cl_kernel kernel;
    cl_command_queue queue;
    cl_event event;

    /* length of the vector */
    unsigned n = STARPU_VECTOR_GET_NX(buffers[0]);
    /* OpenCL copy of the vector pointer */
    cl_mem val = (cl_mem)STARPU_VECTOR_GET_DEV_HANDLE(buffers[0]);

    id = starpu_worker_get_id();
    devid = starpu_worker_get_devid(id);

    err = starpu_opencl_load_kernel(&kernel, &queue, &programs, "vector_mult_opencl",
                                    devid);
    if (err != CL_SUCCESS) STARPU_OPENCL_REPORT_ERROR(err);

    err = clSetKernelArg(kernel, 0, sizeof(val), &val);
    err |= clSetKernelArg(kernel, 1, sizeof(n), &n);
    err |= clSetKernelArg(kernel, 2, sizeof(*factor), factor);
    if (err) STARPU_OPENCL_REPORT_ERROR(err);

    @{
        size_t global=n;
        size_t local;
        size_t s;
        cl_device_id device;

        starpu_opencl_get_device(devid, &device);
        err = clGetKernelWorkGroupInfo (kernel, device, CL_KERNEL_WORK_GROUP_SIZE,
                                        sizeof(local), &local, &s);
        if (err != CL_SUCCESS) STARPU_OPENCL_REPORT_ERROR(err);
        if (local > global) local=global;

        err = clEnqueueNDRangeKernel(queue, kernel, 1, NULL, &global, &local, 0,
                                     NULL, &event);
        if (err != CL_SUCCESS) STARPU_OPENCL_REPORT_ERROR(err);
    @}

    clFinish(queue);
    starpu_opencl_collect_stats(event);
    clReleaseEvent(event);

    starpu_opencl_release_kernel(kernel);
@}
@end smallexample