void roi_sampling_backward_impl()

in src/roi_sampling/roi_sampling_cpu.cpp [80:108]

• 23 lines of code
• 5 McCabe index (conditional complexity)

void roi_sampling_backward_impl(
    at::TensorAccessor<scalar_t, 4> dy,
    at::TensorAccessor<coord_t, 2> bbx,
    at::TensorAccessor<int64_t, 1> idx,
    at::TensorAccessor<scalar_t, 4> dx,
    Sampler sampler) {
  auto roi_height = static_cast<coord_t>(dy.size(2)),
       roi_width  = static_cast<coord_t>(dy.size(3));

  for (int64_t n = 0; n < idx.size(0); ++n) {
    auto img_idx = idx[n];
    auto i0 = bbx[n][0], j0 = bbx[n][1], i1 = bbx[n][2], j1 = bbx[n][3];

    for (int64_t c = 0; c < dy.size(1); ++c) {
      // Create indexer for this plane and image
      auto accessor = dx[img_idx][c];

      for (int64_t i_roi = 0; i_roi < dy.size(2); ++i_roi) {
        auto y_img = roi_to_img(static_cast<coord_t>(i_roi) + coord_t(0.5), i0, i1, roi_height);

        for (int64_t j_roi = 0; j_roi < dy.size(3); ++j_roi) {
          auto x_img = roi_to_img(static_cast<coord_t>(j_roi) + coord_t(0.5), j0, j1, roi_width);

          sampler.backward(y_img, x_img, dy[n][c][i_roi][j_roi], accessor);
        }
      }
    }
  }
}