device_filter.c

/*
 * This file is part of cf4ocl (C Framework for OpenCL).
 *
 * cf4ocl is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * cf4ocl is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with cf4ocl.  If not, see <http://www.gnu.org/licenses/>.
 * */

/*
 * Description
 * -----------
 *
 * Example program which demonstrates advanced usage of device selection using
 * filters.
 *
 * The program accepts one command-line argument which specifies if device
 * filtering is to be performed for context creation (option 1), or just for
 * listing the filtered devices (option 2).
 *
 * */

#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <cf4ocl2.h>

/* Error handling macros. */
#define ERROR_MSG_AND_EXIT(msg) \
    do { fprintf(stderr, "\n%s\n", msg); exit(EXIT_FAILURE); } while(0)

#define HANDLE_ERROR(err) \
    if (err != NULL) { ERROR_MSG_AND_EXIT(err->message); }

/* Usage string. */
#define USAGE \
    "Usage: device_filter 1|2\n\n1 - " \
    "Create context with filtered devices\n" \
    "2 - List filtered devices\n"

int main(int argc, char* argv[]) {

    /* cf4ocl objects. */
    CCLContext* ctx;
    CCLDevSelFilters filters = NULL;
    CCLDevSelDevices devices;

    /* Other variables. */
    cl_uint num_devs;
    char* dev_name;
    int op;

    /* Error handling object. */
    CCLErr* err = NULL;

    /* Check command-line arguments. */
    if (argc < 2)
        ERROR_MSG_AND_EXIT(USAGE);
    else
        op = atoi(argv[1]);

    /* Add independent filter which accepts CPU devices. */
    ccl_devsel_add_indep_filter(&filters, ccl_devsel_indep_type_cpu, NULL);

    /* Add "same platform" dependent filter. This filter should always be added
     * (usually in last position) for context creation, because all devices in a
     * context must belong to the same platform. */
    ccl_devsel_add_dep_filter(&filters, ccl_devsel_dep_platform, NULL);

    /* Proceed depending on user option. */
    if (op == 1) {
        /* Option 1: use set of filters for context creation. */

        /* Create context wrapper, which must have at least one device. */
        ctx = ccl_context_new_from_filters(&filters, &err);
        HANDLE_ERROR(err);

        /* Get number of devices used in context. */
        num_devs = ccl_context_get_num_devices(ctx, &err);
        HANDLE_ERROR(err);

        /* Give some feedback. */
        printf("Context was successfully created with %d device(s)!\n",
            num_devs);

        /* Free context. */
        ccl_context_destroy(ctx);

    } else if (op == 2) {
        /* Option 2: use set of filters for explicit device selection and
         * listing. Here we manipulate a CCLDevSelDevices object directly, which
         * will be uncommon in client code, except in cases were the the final
         * purpose of device selection is not context creation. */

        /* Perform device selection. */
        devices = ccl_devsel_select(&filters, &err);
        HANDLE_ERROR(err);

        /* List selected devices. */
        if (devices->len > 0) {
            printf("%d devices were accepted by the filters:\n", devices->len);
            for (unsigned int i = 0; i < devices->len; ++i) {
                dev_name = ccl_device_get_info_array(
                    devices->pdata[i], CL_DEVICE_NAME, char*, &err);
                HANDLE_ERROR(err);
                printf("\t%d - %s\n", i + 1, dev_name);
            } /* For */
        } else {
            ERROR_MSG_AND_EXIT("No devices were accepted by the filters.");
        } /* If */

        /* Free array object containing device wrappers. */
        ccl_devsel_devices_destroy(devices);

    } else {

        /* Unknown option. */
        ERROR_MSG_AND_EXIT(USAGE);

    }

    /* Check all wrappers have been destroyed. */
    assert(ccl_wrapper_memcheck());

    /* Bye. */
    return EXIT_SUCCESS;

}