//
//   Copyright 2013 Pixar
//
//   Licensed under the Apache License, Version 2.0 (the "Apache License")
//   with the following modification; you may not use this file except in
//   compliance with the Apache License and the following modification to it:
//   Section 6. Trademarks. is deleted and replaced with:
//
//   6. Trademarks. This License does not grant permission to use the trade
//      names, trademarks, service marks, or product names of the Licensor
//      and its affiliates, except as required to comply with Section 4(c) of
//      the License and to reproduce the content of the NOTICE file.
//
//   You may obtain a copy of the Apache License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
//
//   Unless required by applicable law or agreed to in writing, software
//   distributed under the Apache License with the above modification is
//   distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
//   KIND, either express or implied. See the Apache License for the specific
//   language governing permissions and limitations under the Apache License.
//

#ifndef OSD_CUDA_INIT_H
#define OSD_CUDA_INIT_H

#include <algorithm>
#include <cstdio>

// From "NVIDIA GPU Computing SDK 4.2/C/common/inc/cutil_inline_runtime.h":

// Beginning of GPU Architecture definitions
inline int _ConvertSMVer2Cores_local(int major, int minor)
{
    // Defines for GPU Architecture types (using the SM version to determine the # of cores per SM
    typedef struct {
        int SM; // 0xMm (hexidecimal notation), M = SM Major version, and m = SM minor version
        int Cores;
    } sSMtoCores;

    sSMtoCores nGpuArchCoresPerSM[] =
    { { 0x10,  8 }, // Tesla Generation (SM 1.0) G80 class
      { 0x11,  8 }, // Tesla Generation (SM 1.1) G8x class
      { 0x12,  8 }, // Tesla Generation (SM 1.2) G9x class
      { 0x13,  8 }, // Tesla Generation (SM 1.3) GT200 class
      { 0x20, 32 }, // Fermi Generation (SM 2.0) GF100 class
      { 0x21, 48 }, // Fermi Generation (SM 2.1) GF10x class
      { 0x30, 192}, // Fermi Generation (SM 3.0) GK10x class
      {   -1, -1 }
    };

    int index = 0;
    while (nGpuArchCoresPerSM[index].SM != -1) {
        if (nGpuArchCoresPerSM[index].SM == ((major << 4) + minor) ) {
            return nGpuArchCoresPerSM[index].Cores;
        }
        index++;
    }
    printf("MapSMtoCores undefined SMversion %d.%d!\n", major, minor);
    return -1;
}
// end of GPU Architecture definitions

// This function returns the best GPU (with maximum GFLOPS)
inline int cutGetMaxGflopsDeviceId()
{
    int current_device   = 0, sm_per_multiproc = 0;
    int max_compute_perf = 0, max_perf_device  = 0;
    int device_count     = 0, best_SM_arch     = 0;
    cudaDeviceProp deviceProp;

    cudaGetDeviceCount( &device_count );
    // Find the best major SM Architecture GPU device
    while ( current_device < device_count ) {
        cudaGetDeviceProperties( &deviceProp, current_device );
        if (deviceProp.major > 0 && deviceProp.major < 9999) {
            best_SM_arch = std::max(best_SM_arch, deviceProp.major);
        }
        current_device++;
    }

    // Find the best CUDA capable GPU device
    current_device = 0;
    while( current_device < device_count ) {
        cudaGetDeviceProperties( &deviceProp, current_device );
        if (deviceProp.major == 9999 && deviceProp.minor == 9999) {
            sm_per_multiproc = 1;
        } else {
            sm_per_multiproc = _ConvertSMVer2Cores_local(deviceProp.major, deviceProp.minor);
        }
        int compute_perf  = deviceProp.multiProcessorCount * sm_per_multiproc * deviceProp.clockRate;
        if( compute_perf  > max_compute_perf ) {
            // If we find GPU with SM major > 2, search only these
            if ( best_SM_arch > 2 ) {
                // If our device==dest_SM_arch, choose this, or else pass
                if (deviceProp.major == best_SM_arch) {
                    max_compute_perf  = compute_perf;
                    max_perf_device   = current_device;
                }
            } else {
                max_compute_perf  = compute_perf;
                max_perf_device   = current_device;
            }
        }
        ++current_device;
    }
    return max_perf_device;
}

#endif //OSD_CUDA_INIT_H