maxpool_layer.c

#include "maxpool_layer.h"
#include <stdio.h>

image get_maxpool_image(maxpool_layer l)
{
    int h = l.out_h;
    int w = l.out_w;
    int c = l.c;
    return float_to_image(w,h,c,l.output);
}

image get_maxpool_delta(maxpool_layer l)
{
    int h = l.out_h;
    int w = l.out_w;
    int c = l.c;
    return float_to_image(w,h,c,l.delta);
}

maxpool_layer make_maxpool_layer(int batch, int h, int w, int c, int size, int stride, int padding)
{
    maxpool_layer l = {0};
    l.type = MAXPOOL;
    l.batch = batch;
    l.h = h;
    l.w = w;
    l.c = c;
    l.pad = padding;
    l.out_w = (w + 2*padding - size)/stride + 1;
	l.out_h = (h + 2*padding - size)/stride + 1;
    l.out_c = c;
    l.outputs = l.out_h * l.out_w * l.out_c;
    l.inputs = h*w*c;
    l.size = size;
    l.stride = stride;
    int output_size = l.out_h * l.out_w * l.out_c * batch;
    l.indexes = calloc(output_size, sizeof(int));
    l.output =  calloc(output_size, sizeof(float));
    l.delta =   calloc(output_size, sizeof(float));
    l.forward = forward_maxpool_layer;
    l.backward = backward_maxpool_layer;
    #ifdef GPU
    l.forward_gpu = forward_maxpool_layer_gpu;
    l.backward_gpu = backward_maxpool_layer_gpu;
    l.indexes_gpu = cuda_make_int_array(0, output_size);
    l.output_gpu  = cuda_make_array(l.output, output_size);
    l.delta_gpu   = cuda_make_array(l.delta, output_size);
    #endif
    fprintf(stderr, "max          %d x %d / %d  %4d x%4d x%4d   ->  %4d x%4d x%4d\n", size, size, stride, w, h, c, l.out_w, l.out_h, l.out_c);
    return l;
}

void resize_maxpool_layer(maxpool_layer *l, int w, int h)
{
    l->h = h;
    l->w = w;
    l->inputs = h*w*l->c;

    l->out_w = (w + 2*l->pad)/l->stride;
    l->out_h = (h + 2*l->pad)/l->stride;
    l->outputs = l->out_w * l->out_h * l->c;
    int output_size = l->outputs * l->batch;

    l->indexes = realloc(l->indexes, output_size * sizeof(int));
    l->output = realloc(l->output, output_size * sizeof(float));
    l->delta = realloc(l->delta, output_size * sizeof(float));

    #ifdef GPU
    cuda_free((float *)l->indexes_gpu);
    cuda_free(l->output_gpu);
    cuda_free(l->delta_gpu);
    l->indexes_gpu = cuda_make_int_array(0, output_size);
    l->output_gpu  = cuda_make_array(l->output, output_size);
    l->delta_gpu   = cuda_make_array(l->delta,  output_size);
    #endif
}

#ifdef NNPACK
struct maxpool_params {
	const maxpool_layer *l;
	network *net;
};

void maxpool_thread(struct maxpool_params *params, size_t b, size_t k)
{
	int i, j, m, n;
	int w_offset = -params->l->pad;
	int h_offset = -params->l->pad;
	int h = params->l->out_h;
	int w = params->l->out_w;
	int c = params->l->c;

	for(i = 0; i < h; ++i){
		for(j = 0; j < w; ++j){
			int out_index = j + w*(i + h*(k + c*b));
			float max = -FLT_MAX;
			int max_i = -1;
			for(n = 0; n < params->l->size; ++n){
				for(m = 0; m < params->l->size; ++m){
					int cur_h = h_offset + i*params->l->stride + n;
					int cur_w = w_offset + j*params->l->stride + m;
					int index = cur_w + params->l->w*(cur_h + params->l->h*(k + b*params->l->c));
					int valid = (cur_h >= 0 && cur_h < params->l->h &&
								 cur_w >= 0 && cur_w < params->l->w);
					float val = (valid != 0) ? params->net->input[index] : -FLT_MAX;
					max_i = (val > max) ? index : max_i;
					max   = (val > max) ? val   : max;
				}
			}
			params->l->output[out_index] = max;
			params->l->indexes[out_index] = max_i;
		}
	}
}
#endif

void forward_maxpool_layer(const maxpool_layer l, network net)
{
#ifdef NNPACK
	struct maxpool_params params = { &l, &net };
	pthreadpool_compute_2d(net.threadpool, (pthreadpool_function_2d_t)maxpool_thread,
		&params, l.batch, l.c);
#else
	int b,i,j,k,m,n;
	int w_offset = -l.pad;
	int h_offset = -l.pad;

	int h = l.out_h;
	int w = l.out_w;
	int c = l.c;

	for(b = 0; b < l.batch; ++b){
		for(k = 0; k < c; ++k){
			for(i = 0; i < h; ++i){
				for(j = 0; j < w; ++j){
					int out_index = j + w*(i + h*(k + c*b));
					float max = -FLT_MAX;
					int max_i = -1;
					for(n = 0; n < l.size; ++n){
						for(m = 0; m < l.size; ++m){
							int cur_h = h_offset + i*l.stride + n;
							int cur_w = w_offset + j*l.stride + m;
							int index = cur_w + l.w*(cur_h + l.h*(k + b*l.c));
							int valid = (cur_h >= 0 && cur_h < l.h &&
										 cur_w >= 0 && cur_w < l.w);
							float val = (valid != 0) ? net.input[index] : -FLT_MAX;
							max_i = (val > max) ? index : max_i;
							max   = (val > max) ? val   : max;
						}
					}
					l.output[out_index] = max;
					l.indexes[out_index] = max_i;
				}
			}
		}
	}
#endif
}

void backward_maxpool_layer(const maxpool_layer l, network net)
{
    int i;
    int h = l.out_h;
    int w = l.out_w;
    int c = l.c;
    for(i = 0; i < h*w*c*l.batch; ++i){
        int index = l.indexes[i];
        net.delta[index] += l.delta[i];
    }
}