text: #include "avgpool_layer.h"
  #include "cuda.h"
  #include <stdio.h>
  
  avgpool_layer make_avgpool_layer(int batch, int w, int h, int c)
  {
      fprintf(stderr, "avg                     %4d x%4d x%4d   ->  %4d\n",  w, h, c, c);
      avgpool_layer l = {};
      l.type = AVGPOOL;
      l.batch = batch;
      l.h = h;
      l.w = w;
      l.c = c;
      l.out_w = 1;
      l.out_h = 1;
      l.out_c = c;
      l.outputs = l.out_c;
      l.inputs = h*w*c;
      int output_size = l.outputs * batch;
      l.output = (float*) calloc(output_size, sizeof(float));
      l.delta =   (float*)calloc(output_size, sizeof(float));
      l.forward = forward_avgpool_layer;
      l.backward = backward_avgpool_layer;
      #ifdef GPU
      l.forward_gpu = forward_avgpool_layer_gpu;
      l.backward_gpu = backward_avgpool_layer_gpu;
      l.output_gpu  = cuda_make_array(l.output, output_size);
      l.delta_gpu   = cuda_make_array(l.delta, output_size);
      #endif
      return l;
  }
  
  void resize_avgpool_layer(avgpool_layer *l, int w, int h)
  {
      l->w = w;
      l->h = h;
      l->inputs = h*w*l->c;
  }
  
  void forward_avgpool_layer(const avgpool_layer l, network net)
  {
      int b,i,k;
  
      for(b = 0; b < l.batch; ++b){
          for(k = 0; k < l.c; ++k){
              int out_index = k + b*l.c;
              l.output[out_index] = 0;
              for(i = 0; i < l.h*l.w; ++i){
                  int in_index = i + l.h*l.w*(k + b*l.c);
                  l.output[out_index] += net.input[in_index];
              }
              l.output[out_index] /= l.h*l.w;
          }
      }
  }
  
  void backward_avgpool_layer(const avgpool_layer l, network net)
  {
      int b,i,k;
  
      for(b = 0; b < l.batch; ++b){
          for(k = 0; k < l.c; ++k){
              int out_index = k + b*l.c;
              for(i = 0; i < l.h*l.w; ++i){
                  int in_index = i + l.h*l.w*(k + b*l.c);
                  net.delta[in_index] += l.delta[out_index] / (l.h*l.w);
              }
          }
      }
  }
  
  