Class Platform

include/CL/opencl.hpp:2646–3001

! \brief Class interface for cl_platform_id. * * \note Copies of these objects are inexpensive, since they don't 'own' * any underlying resources or data structures. * * \see cl_platform_id */

 *  \see cl_platform_id
 */
class Platform : public detail::Wrapper<cl_platform_id>
{
private:
    static std::once_flag default_initialized_;
    static Platform default_;
    static cl_int default_error_;

    /*! \brief Create the default context.
    *
    * This sets @c default_ and @c default_error_. It does not throw
    * @c cl::Error.
    */
    static void makeDefault() {
        /* Throwing an exception from a call_once invocation does not do
        * what we wish, so we catch it and save the error.
        */
#if defined(CL_HPP_ENABLE_EXCEPTIONS)
        try
#endif
        {
            // If default wasn't passed ,generate one
            // Otherwise set it
            cl_uint n = 0;

            cl_int err = ::clGetPlatformIDs(0, nullptr, &n);
            if (err != CL_SUCCESS) {
                default_error_ = err;
                return;
            }
            if (n == 0) {
                default_error_ = CL_INVALID_PLATFORM;
                return;
            }

            vector<cl_platform_id> ids(n);
            err = ::clGetPlatformIDs(n, ids.data(), nullptr);
            if (err != CL_SUCCESS) {
                default_error_ = err;
                return;
            }

            default_ = Platform(ids[0]);
        }
#if defined(CL_HPP_ENABLE_EXCEPTIONS)
        catch (cl::Error &e) {
            default_error_ = e.err();
        }
#endif
    }

    /*! \brief Create the default platform from a provided platform.
     *
     * This sets @c default_. It does not throw
     * @c cl::Error.
     */
    static void makeDefaultProvided(const Platform &p) {
       default_ = p;
    }