example_sgemv.c

This is an example of how to use the clblasSgemvEx function.

/* ************************************************************************
 * Copyright 2013 Advanced Micro Devices, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * ************************************************************************/

#include <sys/types.h>
#include <stdio.h>
#include <string.h>

/* Include CLBLAS header. It automatically includes needed OpenCL header,
 * so we can drop out explicit inclusion of cl.h header.
 */
#include <clBLAS.h>

/* This example uses predefined matrices and their characteristics for
 * simplicity purpose.
 */
static const clblasOrder order = clblasRowMajor;

static const size_t M = 4;
static const size_t N = 5;

static const cl_float alpha = 10;

static const clblasTranspose transA = clblasNoTrans;
static const cl_float A[] = {
    11, 12, 13, 14, 15,
    21, 22, 23, 24, 25,
    31, 32, 33, 34, 35,
    41, 42, 43, 44, 45
};
static const size_t lda = 5;        /* i.e. lda = N */

static const cl_float X[] = {
    11,
    21,
    31,
    41,
    51,
};
static const int incx = 1;

static const cl_float beta = 20;

static cl_float Y[] = {
    11,
    21,
    31,
    41,
};
static const int incy = 1;

static cl_float result[4];          /* M */

static const size_t off  = 1;
static const size_t offA = 5 + 1;   /* M + off */
static const size_t offX = 1;       /* off */
static const size_t offY = 1;       /* off */

static void
printResult(const char* str)
{
    size_t i, nElements;

    printf("%s:\n", str);

    nElements = (sizeof(result) / sizeof(cl_float)) / incy;
    for (i = 0; i < nElements; i++) {
        printf("%d\n", (int)result[i * incy]);
    }
}

int
main(void)
{
    cl_int err;
    cl_platform_id platform = 0;
    cl_device_id device = 0;
    cl_context_properties props[3] = { CL_CONTEXT_PLATFORM, 0, 0 };
    cl_context ctx = 0;
    cl_command_queue queue = 0;
    cl_mem bufA, bufX, bufY;
    cl_event event = NULL;
    int ret = 0;

    /* Setup OpenCL environment. */
    err = clGetPlatformIDs(1, &platform, NULL);
    if (err != CL_SUCCESS) {
        printf( "clGetPlatformIDs() failed with %d\n", err );
        return 1;
    }

    err = clGetDeviceIDs(platform, CL_DEVICE_TYPE_GPU, 1, &device, NULL);
    if (err != CL_SUCCESS) {
        printf( "clGetDeviceIDs() failed with %d\n", err );
        return 1;
    }

    props[1] = (cl_context_properties)platform;
    ctx = clCreateContext(props, 1, &device, NULL, NULL, &err);
    if (err != CL_SUCCESS) {
        printf( "clCreateContext() failed with %d\n", err );
        return 1;
    }

    queue = clCreateCommandQueue(ctx, device, 0, &err);
    if (err != CL_SUCCESS) {
        printf( "clCreateCommandQueue() failed with %d\n", err );
        clReleaseContext(ctx);
        return 1;
    }

    /* Setup clblas. */
    err = clblasSetup();
    if (err != CL_SUCCESS) {
        printf("clblasSetup() failed with %d\n", err);
        clReleaseCommandQueue(queue);
        clReleaseContext(ctx);
        return 1;
    }

    /* Prepare OpenCL memory objects and place matrices inside them. */
    bufA = clCreateBuffer(ctx, CL_MEM_READ_ONLY, M * N * sizeof(*A),
                          NULL, &err);
    bufX = clCreateBuffer(ctx, CL_MEM_READ_ONLY, N * sizeof(*X),
                          NULL, &err);
    bufY = clCreateBuffer(ctx, CL_MEM_READ_WRITE, M * sizeof(*Y),
                          NULL, &err);

    err = clEnqueueWriteBuffer(queue, bufA, CL_TRUE, 0,
        M * N * sizeof(*A), A, 0, NULL, NULL);
    err = clEnqueueWriteBuffer(queue, bufX, CL_TRUE, 0,
        N * sizeof(*X), X, 0, NULL, NULL);
    err = clEnqueueWriteBuffer(queue, bufY, CL_TRUE, 0,
        M * sizeof(*Y), Y, 0, NULL, NULL);

    /* Call clblas extended function. */
    err = clblasSgemv(order, transA, M - off, N - off, alpha,
                           bufA, offA, lda, bufX, offX, incx, beta,
                           bufY, offY, incy, 1, &queue, 0, NULL, &event);
    if (err != CL_SUCCESS) {
        printf("clblasSgemvEx() failed with %d\n", err);
        ret = 1;
    }
    else {
        /* Wait for calculations to be finished. */
        err = clWaitForEvents(1, &event);

        /* Fetch results of calculations from GPU memory. */
        err = clEnqueueReadBuffer(queue, bufY, CL_TRUE, 0, M * sizeof(*result),
                                  result, 0, NULL, NULL);
        /* At this point you will get the result of SGEMV placed in 'result' array. */
        puts("");
        printResult("clblasSgemvEx result");
    }

    /* Release OpenCL events. */
    clReleaseEvent(event);

    /* Release OpenCL memory objects. */
    clReleaseMemObject(bufY);
    clReleaseMemObject(bufX);
    clReleaseMemObject(bufA);

    /* Finalize work with clblas. */
    clblasTeardown();

    /* Release OpenCL working objects. */
    clReleaseCommandQueue(queue);
    clReleaseContext(ctx);

    return ret;
}