DRY up code, add comments

src/caffe/layers/spp_layer.cpp

@@ -22,18 +22,14 @@ LayerParameter SPPLayer<Dtype>::GetPoolingParam(const int pyramid_level,
   // find padding and kernel size so that the pooling is
   // performed across the entire image
   int kernel_h = ceil(bottom_h / static_cast<double>(num_bins));
-  int pad_h = 0;
+  // remainder_h is the min number of pixels that need to be padded
+  // before entire image is pooled over with the chosen kernel dimension
   int remainder_h = kernel_h * num_bins - bottom_h;
-  if (bottom_h % num_bins > 0) {
-    pad_h = (remainder_h + 1) / 2;
-  }
+  int pad_h = (remainder_h + 1) / 2;
 
   int kernel_w = ceil(bottom_w / static_cast<double>(num_bins));
-  int pad_w = 0;
   int remainder_w = kernel_w * num_bins - bottom_w;
-  if (bottom_w % num_bins > 0) {
-    pad_w = (remainder_w + 1) / 2;
-  }
+  int pad_w = (remainder_w + 1) / 2;
 
   pooling_param.mutable_pooling_param()->set_pad_h(pad_h);
   pooling_param.mutable_pooling_param()->set_pad_w(pad_w);