Add PSROIPooling layer forward CPU implementation by stealing code from its GPU implentation

src/caffe/layers/psroi_pooling_layer.cpp

@@ -19,6 +19,84 @@ using std::floor;
 using std::ceil;
 
 namespace caffe {
+  template <typename Dtype>
+  void PSROIPoolingForward_cpu(
+  		const int count,
+  		const Dtype* bottom_data,
+  		const Dtype spatial_scale,
+  		const int channels,
+  		const int height, const int width,
+  		const int pooled_height, const int pooled_width,
+  		const Dtype* bottom_rois,
+  		const int output_dim,
+  		const int group_size,
+  		Dtype* top_data,
+  		int* mapping_channel) {
+  	const Dtype* bottom_data_bak = bottom_data;
+  	const Dtype* bottom_rois_bak = bottom_rois;
+
+  	for(int index = 0; index < count; ++index) {
+  		bottom_data = bottom_data_bak;
+  		bottom_rois = bottom_rois_bak;
+  		// The output is in order (n, ctop, ph, pw)
+  		int pw = index % pooled_width;
+  		int ph = (index / pooled_width) % pooled_height;
+  		int ctop = (index / pooled_width / pooled_height) % output_dim;
+  		int n = index / pooled_width / pooled_height / output_dim;
+
+  		// [start, end) interval for spatial sampling
+  		bottom_rois += n * 5;
+  		int roi_batch_ind = bottom_rois[0];
+  		Dtype roi_start_w =
+  		static_cast<Dtype>(round(bottom_rois[1])) * spatial_scale;
+  		Dtype roi_start_h =
+  		static_cast<Dtype>(round(bottom_rois[2])) * spatial_scale;
+  		Dtype roi_end_w =
+  		static_cast<Dtype>(round(bottom_rois[3]) + 1.) * spatial_scale;
+  		Dtype roi_end_h =
+  		static_cast<Dtype>(round(bottom_rois[4]) + 1.) * spatial_scale;
+
+  		// Force too small ROIs to be 1x1
+  		Dtype roi_width = max(roi_end_w - roi_start_w, static_cast<Dtype>(0.1f));// avoid 0
+  		Dtype roi_height = max(roi_end_h - roi_start_h, static_cast<Dtype>(0.1f));
+
+  		// Compute w and h at bottom
+  		Dtype bin_size_h = roi_height / static_cast<Dtype>(pooled_height);
+  		Dtype bin_size_w = roi_width / static_cast<Dtype>(pooled_width);
+
+  		int hstart = floor(static_cast<Dtype>(ph) * bin_size_h
+  				+ roi_start_h);
+  		int wstart = floor(static_cast<Dtype>(pw)* bin_size_w
+  				+ roi_start_w);
+  		int hend = ceil(static_cast<Dtype>(ph + 1) * bin_size_h
+  				+ roi_start_h);
+  		int wend = ceil(static_cast<Dtype>(pw + 1) * bin_size_w
+  				+ roi_start_w);
+  		// Add roi offsets and clip to input boundaries
+  		hstart = min(max(hstart, 0), height);
+  		hend = min(max(hend, 0), height);
+  		wstart = min(max(wstart, 0), width);
+  		wend = min(max(wend, 0), width);
+  		bool is_empty = (hend <= hstart) || (wend <= wstart);
+
+  		int gw = pw;
+  		int gh = ph;
+  		int c = (ctop*group_size + gh)*group_size + gw;
+
+  		bottom_data += (roi_batch_ind * channels + c) * height * width;
+  		Dtype out_sum = 0;
+  		for (int h = hstart; h < hend; ++h) {
+  			for (int w = wstart; w < wend; ++w) {
+  				int bottom_index = h*width + w;
+  				out_sum += bottom_data[bottom_index];
+  			}
+  		}
+  		Dtype bin_area = (hend - hstart)*(wend - wstart);
+  		top_data[index] = is_empty? 0. : out_sum/bin_area;
+  		mapping_channel[index] = c;
+  	}
+  }
+
   template <typename Dtype>
   void PSROIPoolingLayer<Dtype>::LayerSetUp(const vector<Blob<Dtype>*>& bottom,
     const vector<Blob<Dtype>*>& top){
@@ -52,7 +130,17 @@ namespace caffe {
   template <typename Dtype>
   void PSROIPoolingLayer<Dtype>::Forward_cpu(const vector<Blob<Dtype>*>& bottom,
     const vector<Blob<Dtype>*>& top){
-    NOT_IMPLEMENTED;
+    const Dtype* bottom_data = bottom[0]->cpu_data();
+    const Dtype* bottom_rois = bottom[1]->cpu_data();
+    Dtype* top_data = top[0]->mutable_cpu_data();
+    int* mapping_channel_ptr = mapping_channel_.mutable_cpu_data();
+    int count = top[0]->count();
+    caffe_set(count, Dtype(0), top_data);
+    caffe_set(count, -1, mapping_channel_ptr);
+    PSROIPoolingForward_cpu(count, bottom_data, spatial_scale_,
+      channels_, height_, width_, pooled_height_,
+      pooled_width_, bottom_rois, output_dim_, group_size_,
+      top_data, mapping_channel_ptr);
   }
 
   template <typename Dtype>
@@ -67,4 +155,4 @@ namespace caffe {
   INSTANTIATE_CLASS(PSROIPoolingLayer);
   REGISTER_LAYER_CLASS(PSROIPooling);
 
-}
+}