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__kernel void MaxPoolForward(const int nthreads,
    __global T* bottom_data, const int num, const int channels, const int height, const int width,
    const int pooled_height, const int pooled_width, const int kernel_h, const int kernel_w,
    const int stride_h, const int stride_w, const int pad_h, const int pad_w,
    __global T* top_data
#ifdef MASK
    , __global float* mask
#endif
    )
{
  int index = get_global_id(0);
  int tmp = get_global_size(0);
  for(index; index < nthreads; index += tmp) {
    int pw = index % pooled_width;
    int ph = (index / pooled_width) % pooled_height;
    int c = (index / pooled_width / pooled_height) % channels;
    int n = index / pooled_width / pooled_height / channels;
    int hstart = ph * stride_h - pad_h;
    int wstart = pw * stride_w - pad_w;
    const int hend = min(hstart + kernel_h, height);
    const int wend = min(wstart + kernel_w, width);
    hstart = max(hstart, 0);
    wstart = max(wstart, 0);
    T maxval = -FLT_MAX;
    int maxidx = -1;
    bottom_data =
    bottom_data + (n * channels + c) * height * width;
    for (int h = hstart; h < hend; ++h) {
      for (int w = wstart; w < wend; ++w) {
        if (bottom_data[h * width + w] > maxval) {
          maxidx = h * width + w;
          maxval = bottom_data[maxidx];
        }
      }
    }

    top_data[index] = maxval;

#ifdef MASK
    mask[index] = maxidx;
#endif
  }
}

__kernel void AvePoolForward(const int nthreads,
    __global T* bottom_data, const int num, const int channels, const int height, const int width,
    const int pooled_height, const int pooled_width, const int kernel_h, const int kernel_w,
    const int stride_h, const int stride_w, const int pad_h, const int pad_w,
    __global T* top_data
#ifdef MASK
    , __global float* mask // NOT USED
#endif
    )
{
  int index = get_global_id(0);
  int tmp = get_global_size(0);
  for(index; index < nthreads; index+=tmp) {
    int pw = index % pooled_width;
    int ph = (index / pooled_width) % pooled_height;
    int c = (index / pooled_width / pooled_height) % channels;
    int n = index / pooled_width / pooled_height / channels; int hstart = ph * stride_h - pad_h; int wstart = pw * stride_w - pad_w;
    int hend = min(hstart + kernel_h, height + pad_h);
    int wend = min(wstart + kernel_w, width + pad_w);
    const int pool_size = (hend - hstart) * (wend - wstart);
    hstart = max(hstart, 0);
    wstart = max(wstart, 0);
    hend = min(hend, height);
    wend = min(wend, width);
    T aveval = 0;
    bottom_data =
    bottom_data + (n * channels + c) * height * width;
    for (int h = hstart; h < hend; ++h) {
      for (int w = wstart; w < wend; ++w) {
        aveval += bottom_data[h * width + w];
      }
    }
    top_data[index] = aveval / pool_size;
  }

}
