#include "maxpool_layer.h"
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#include <stdio.h>
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image get_maxpool_image(maxpool_layer layer)
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{
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int h = (layer.h-1)/layer.stride + 1;
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int w = (layer.w-1)/layer.stride + 1;
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int c = layer.c;
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return float_to_image(h,w,c,layer.output);
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}
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image get_maxpool_delta(maxpool_layer layer)
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{
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int h = (layer.h-1)/layer.stride + 1;
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int w = (layer.w-1)/layer.stride + 1;
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int c = layer.c;
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return float_to_image(h,w,c,layer.delta);
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}
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maxpool_layer *make_maxpool_layer(int batch, int h, int w, int c, int stride)
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{
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c = c*batch;
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fprintf(stderr, "Maxpool Layer: %d x %d x %d image, %d stride\n", h,w,c,stride);
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maxpool_layer *layer = calloc(1, sizeof(maxpool_layer));
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layer->batch = batch;
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layer->h = h;
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layer->w = w;
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layer->c = c;
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layer->stride = stride;
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layer->output = calloc(((h-1)/stride+1) * ((w-1)/stride+1) * c, sizeof(float));
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layer->delta = calloc(((h-1)/stride+1) * ((w-1)/stride+1) * c, sizeof(float));
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return layer;
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}
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void resize_maxpool_layer(maxpool_layer *layer, int h, int w, int c)
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{
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layer->h = h;
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layer->w = w;
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layer->c = c;
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layer->output = realloc(layer->output, ((h-1)/layer->stride+1) * ((w-1)/layer->stride+1) * c * sizeof(float));
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layer->delta = realloc(layer->delta, ((h-1)/layer->stride+1) * ((w-1)/layer->stride+1) * c * sizeof(float));
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}
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void forward_maxpool_layer(const maxpool_layer layer, float *in)
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{
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image input = float_to_image(layer.h, layer.w, layer.c, in);
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image output = get_maxpool_image(layer);
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int i,j,k;
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for(i = 0; i < output.h*output.w*output.c; ++i) output.data[i] = -DBL_MAX;
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for(k = 0; k < input.c; ++k){
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for(i = 0; i < input.h; ++i){
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for(j = 0; j < input.w; ++j){
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float val = get_pixel(input, i, j, k);
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float cur = get_pixel(output, i/layer.stride, j/layer.stride, k);
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if(val > cur) set_pixel(output, i/layer.stride, j/layer.stride, k, val);
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}
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}
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}
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}
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void backward_maxpool_layer(const maxpool_layer layer, float *in, float *delta)
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{
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image input = float_to_image(layer.h, layer.w, layer.c, in);
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image input_delta = float_to_image(layer.h, layer.w, layer.c, delta);
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image output_delta = get_maxpool_delta(layer);
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image output = get_maxpool_image(layer);
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int i,j,k;
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for(k = 0; k < input.c; ++k){
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for(i = 0; i < input.h; ++i){
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for(j = 0; j < input.w; ++j){
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float val = get_pixel(input, i, j, k);
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float cur = get_pixel(output, i/layer.stride, j/layer.stride, k);
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float d = get_pixel(output_delta, i/layer.stride, j/layer.stride, k);
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if(val == cur) {
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set_pixel(input_delta, i, j, k, d);
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}
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else set_pixel(input_delta, i, j, k, 0);
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}
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}
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}
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}
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