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/*
* Copyright (c) 2016, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
#include <assert.h>
#include <math.h>
#include "aom_dsp/aom_dsp_common.h"
#include "av1/encoder/ml.h"
// Calculate prediction based on the given input features and neural net config.
// Assume there are no more than NN_MAX_NODES_PER_LAYER nodes in each hidden
// layer.
void av1_nn_predict_c(const float *input_nodes,
const NN_CONFIG *const nn_config, float *const output) {
int num_input_nodes = nn_config->num_inputs;
int buf_index = 0;
float buf[2][NN_MAX_NODES_PER_LAYER];
// Propagate hidden layers.
const int num_layers = nn_config->num_hidden_layers;
assert(num_layers <= NN_MAX_HIDDEN_LAYERS);
for (int layer = 0; layer < num_layers; ++layer) {
const float *layer_weights = nn_config->weights[layer];
const float *layer_bias = nn_config->bias[layer];
float *output_nodes = buf[buf_index];
const int num_output_nodes = nn_config->num_hidden_nodes[layer];
assert(num_output_nodes < NN_MAX_NODES_PER_LAYER);
for (int node = 0; node < num_output_nodes; ++node) {
float val = layer_bias[node];
for (int i = 0; i < num_input_nodes; ++i)
val += layer_weights[node * num_input_nodes + i] * input_nodes[i];
// ReLU as activation function.
val = val > 0.0f ? val : 0.0f; // Could use AOMMAX().
output_nodes[node] = val;
}
num_input_nodes = num_output_nodes;
input_nodes = output_nodes;
buf_index = 1 - buf_index;
}
// Final output layer.
const float *layer_weights = nn_config->weights[num_layers];
const float *layer_bias = nn_config->bias[num_layers];
for (int node = 0; node < nn_config->num_outputs; ++node) {
float val = layer_bias[node];
for (int i = 0; i < num_input_nodes; ++i)
val += layer_weights[node * num_input_nodes + i] * input_nodes[i];
output[node] = val;
}
}
void av1_nn_softmax(const float *input, float *output, int n) {
// Softmax function is invariant to adding the same constant
// to all input values, so we subtract the maximum input to avoid
// possible overflow.
float max_inp = input[0];
for (int i = 1; i < n; i++) max_inp = AOMMAX(max_inp, input[i]);
float sum_out = 0.0f;
for (int i = 0; i < n; i++) {
// Clamp to range [-10.0, 0.0] to prevent FE_UNDERFLOW errors.
const float normalized_input = AOMMAX(input[i] - max_inp, -10.0f);
output[i] = (float)exp(normalized_input);
sum_out += output[i];
}
for (int i = 0; i < n; i++) output[i] /= sum_out;
}