209 строки
6.5 KiB
C
209 строки
6.5 KiB
C
/*
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* Copyright (c) 2016, Alliance for Open Media. All rights reserved
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*
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* This source code is subject to the terms of the BSD 2 Clause License and
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* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
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* was not distributed with this source code in the LICENSE file, you can
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* obtain it at www.aomedia.org/license/software. If the Alliance for Open
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* Media Patent License 1.0 was not distributed with this source code in the
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* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
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*/
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#include "./aom_config.h"
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#if CONFIG_DAALA_EC
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#include <string.h>
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#endif
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#include "aom_dsp/prob.h"
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#if CONFIG_DAALA_EC
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#include "aom_dsp/entcode.h"
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#endif
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const uint8_t aom_norm[256] = {
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0, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
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3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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};
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static unsigned int tree_merge_probs_impl(unsigned int i,
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const aom_tree_index *tree,
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const aom_prob *pre_probs,
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const unsigned int *counts,
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aom_prob *probs) {
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const int l = tree[i];
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const unsigned int left_count =
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(l <= 0) ? counts[-l]
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: tree_merge_probs_impl(l, tree, pre_probs, counts, probs);
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const int r = tree[i + 1];
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const unsigned int right_count =
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(r <= 0) ? counts[-r]
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: tree_merge_probs_impl(r, tree, pre_probs, counts, probs);
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const unsigned int ct[2] = { left_count, right_count };
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probs[i >> 1] = mode_mv_merge_probs(pre_probs[i >> 1], ct);
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return left_count + right_count;
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}
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void aom_tree_merge_probs(const aom_tree_index *tree, const aom_prob *pre_probs,
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const unsigned int *counts, aom_prob *probs) {
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tree_merge_probs_impl(0, tree, pre_probs, counts, probs);
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}
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#if CONFIG_DAALA_EC
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typedef struct tree_node tree_node;
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struct tree_node {
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aom_tree_index index;
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uint8_t probs[16];
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uint8_t prob;
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int path;
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int len;
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int l;
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int r;
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uint16_t pdf;
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};
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/* Compute the probability of this node in Q23 */
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static uint32_t tree_node_prob(tree_node n, int i) {
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uint32_t prob;
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/* 1.0 in Q23 */
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prob = 16777216;
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for (; i < n.len; i++) {
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prob = prob * n.probs[i] >> 8;
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}
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return prob;
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}
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static int tree_node_cmp(tree_node a, tree_node b) {
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int i;
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uint32_t pa;
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uint32_t pb;
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for (i = 0; i < OD_MINI(a.len, b.len) && a.probs[i] == b.probs[i]; i++) {
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}
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pa = tree_node_prob(a, i);
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pb = tree_node_prob(b, i);
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return pa > pb ? 1 : pa < pb ? -1 : 0;
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}
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/* Given a Q15 probability for symbol subtree rooted at tree[n], this function
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computes the probability of each symbol (defined as a node that has no
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children). */
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static uint16_t tree_node_compute_probs(tree_node *tree, int n, uint16_t pdf) {
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if (tree[n].l == 0) {
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/* This prevents probability computations in Q15 that underflow from
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producing a symbol that has zero probability. */
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if (pdf == 0) pdf = 1;
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tree[n].pdf = pdf;
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return pdf;
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} else {
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/* We process the smaller probability first, */
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if (tree[n].prob < 128) {
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uint16_t lp;
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uint16_t rp;
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lp = (((uint32_t)pdf) * tree[n].prob + 128) >> 8;
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lp = tree_node_compute_probs(tree, tree[n].l, lp);
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rp = tree_node_compute_probs(tree, tree[n].r, lp > pdf ? 0 : pdf - lp);
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return lp + rp;
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} else {
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uint16_t rp;
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uint16_t lp;
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rp = (((uint32_t)pdf) * (256 - tree[n].prob) + 128) >> 8;
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rp = tree_node_compute_probs(tree, tree[n].r, rp);
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lp = tree_node_compute_probs(tree, tree[n].l, rp > pdf ? 0 : pdf - rp);
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return lp + rp;
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}
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}
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}
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static int tree_node_extract(tree_node *tree, int n, int symb, uint16_t *pdf,
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aom_tree_index *index, int *path, int *len) {
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if (tree[n].l == 0) {
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pdf[symb] = tree[n].pdf;
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if (index != NULL) index[symb] = tree[n].index;
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if (path != NULL) path[symb] = tree[n].path;
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if (len != NULL) len[symb] = tree[n].len;
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return symb + 1;
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} else {
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symb = tree_node_extract(tree, tree[n].l, symb, pdf, index, path, len);
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return tree_node_extract(tree, tree[n].r, symb, pdf, index, path, len);
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}
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}
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int tree_to_cdf(const aom_tree_index *tree, const aom_prob *probs,
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aom_tree_index root, uint16_t *cdf, aom_tree_index *index,
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int *path, int *len) {
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tree_node symb[2 * 16 - 1];
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int nodes;
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int next[16];
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int size;
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int nsymbs;
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int i;
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/* Create the root node with probability 1 in Q15. */
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symb[0].index = root;
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symb[0].path = 0;
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symb[0].len = 0;
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symb[0].l = symb[0].r = 0;
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nodes = 1;
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next[0] = 0;
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size = 1;
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nsymbs = 1;
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while (size > 0 && nsymbs < 16) {
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int m;
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tree_node n;
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aom_tree_index j;
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uint8_t prob;
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m = 0;
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/* Find the internal node with the largest probability. */
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for (i = 1; i < size; i++) {
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if (tree_node_cmp(symb[next[i]], symb[next[m]]) > 0) m = i;
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}
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i = next[m];
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memmove(&next[m], &next[m + 1], sizeof(*next) * (size - (m + 1)));
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size--;
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/* Split this symbol into two symbols */
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n = symb[i];
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j = n.index;
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prob = probs[j >> 1];
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/* Left */
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n.index = tree[j];
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n.path <<= 1;
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n.len++;
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n.probs[n.len - 1] = prob;
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symb[nodes] = n;
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if (n.index > 0) {
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next[size++] = nodes;
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}
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/* Right */
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n.index = tree[j + 1];
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n.path += 1;
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n.probs[n.len - 1] = 256 - prob;
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symb[nodes + 1] = n;
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if (n.index > 0) {
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next[size++] = nodes + 1;
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}
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symb[i].prob = prob;
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symb[i].l = nodes;
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symb[i].r = nodes + 1;
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nodes += 2;
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nsymbs++;
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}
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/* Compute the probabilities of each symbol in Q15 */
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tree_node_compute_probs(symb, 0, 32768);
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/* Extract the cdf, index, path and length */
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tree_node_extract(symb, 0, 0, cdf, index, path, len);
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/* Convert to CDF */
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for (i = 1; i < nsymbs; i++) {
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cdf[i] = cdf[i - 1] + cdf[i];
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}
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return nsymbs;
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}
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#endif
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