summaryrefslogtreecommitdiffstats
path: root/third_party/aom/aom_dsp/prob.c
blob: c60bfdac5b194d0b33c9610b0156e69017fb8d2b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
/*
 * 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 "./aom_config.h"

#if CONFIG_EC_MULTISYMBOL
#include <string.h>
#endif

#include "aom_dsp/prob.h"

const uint8_t aom_norm[256] = {
  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,
  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,
  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,
  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,
  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,
  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,
  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,
  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,
  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,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

static unsigned int tree_merge_probs_impl(unsigned int i,
                                          const aom_tree_index *tree,
                                          const aom_prob *pre_probs,
                                          const unsigned int *counts,
                                          aom_prob *probs) {
  const int l = tree[i];
  const unsigned int left_count =
      (l <= 0) ? counts[-l]
               : tree_merge_probs_impl(l, tree, pre_probs, counts, probs);
  const int r = tree[i + 1];
  const unsigned int right_count =
      (r <= 0) ? counts[-r]
               : tree_merge_probs_impl(r, tree, pre_probs, counts, probs);
  const unsigned int ct[2] = { left_count, right_count };
  probs[i >> 1] = mode_mv_merge_probs(pre_probs[i >> 1], ct);
  return left_count + right_count;
}

void aom_tree_merge_probs(const aom_tree_index *tree, const aom_prob *pre_probs,
                          const unsigned int *counts, aom_prob *probs) {
  tree_merge_probs_impl(0, tree, pre_probs, counts, probs);
}

#if CONFIG_EC_MULTISYMBOL
typedef struct tree_node tree_node;

struct tree_node {
  aom_tree_index index;
  uint8_t probs[16];
  uint8_t prob;
  int path;
  int len;
  int l;
  int r;
  aom_cdf_prob pdf;
};

/* Compute the probability of this node in Q23 */
static uint32_t tree_node_prob(tree_node n, int i) {
  uint32_t prob;
  /* 1.0 in Q23 */
  prob = 16777216;
  for (; i < n.len; i++) {
    prob = prob * n.probs[i] >> 8;
  }
  return prob;
}

static int tree_node_cmp(tree_node a, tree_node b) {
  int i;
  uint32_t pa;
  uint32_t pb;
  for (i = 0; i < AOMMIN(a.len, b.len) && a.probs[i] == b.probs[i]; i++) {
  }
  pa = tree_node_prob(a, i);
  pb = tree_node_prob(b, i);
  return pa > pb ? 1 : pa < pb ? -1 : 0;
}

/* Given a Q15 probability for symbol subtree rooted at tree[n], this function
    computes the probability of each symbol (defined as a node that has no
    children). */
static aom_cdf_prob tree_node_compute_probs(tree_node *tree, int n,
                                            aom_cdf_prob pdf) {
  if (tree[n].l == 0) {
    /* This prevents probability computations in Q15 that underflow from
        producing a symbol that has zero probability. */
    if (pdf == 0) pdf = 1;
    tree[n].pdf = pdf;
    return pdf;
  } else {
    /* We process the smaller probability first,  */
    if (tree[n].prob < 128) {
      aom_cdf_prob lp;
      aom_cdf_prob rp;
      lp = (((uint32_t)pdf) * tree[n].prob + 128) >> 8;
      lp = tree_node_compute_probs(tree, tree[n].l, lp);
      rp = tree_node_compute_probs(tree, tree[n].r, lp > pdf ? 0 : pdf - lp);
      return lp + rp;
    } else {
      aom_cdf_prob rp;
      aom_cdf_prob lp;
      rp = (((uint32_t)pdf) * (256 - tree[n].prob) + 128) >> 8;
      rp = tree_node_compute_probs(tree, tree[n].r, rp);
      lp = tree_node_compute_probs(tree, tree[n].l, rp > pdf ? 0 : pdf - rp);
      return lp + rp;
    }
  }
}

static int tree_node_extract(tree_node *tree, int n, int symb,
                             aom_cdf_prob *pdf, aom_tree_index *index,
                             int *path, int *len) {
  if (tree[n].l == 0) {
    pdf[symb] = tree[n].pdf;
    if (index != NULL) index[symb] = tree[n].index;
    if (path != NULL) path[symb] = tree[n].path;
    if (len != NULL) len[symb] = tree[n].len;
    return symb + 1;
  } else {
    symb = tree_node_extract(tree, tree[n].l, symb, pdf, index, path, len);
    return tree_node_extract(tree, tree[n].r, symb, pdf, index, path, len);
  }
}

int tree_to_cdf(const aom_tree_index *tree, const aom_prob *probs,
                aom_tree_index root, aom_cdf_prob *cdf, aom_tree_index *index,
                int *path, int *len) {
  tree_node symb[2 * 16 - 1];
  int nodes;
  int next[16];
  int size;
  int nsymbs;
  int i;
  /* Create the root node with probability 1 in Q15. */
  symb[0].index = root;
  symb[0].path = 0;
  symb[0].len = 0;
  symb[0].l = symb[0].r = 0;
  nodes = 1;
  next[0] = 0;
  size = 1;
  nsymbs = 1;
  while (size > 0 && nsymbs < 16) {
    int m;
    tree_node n;
    aom_tree_index j;
    uint8_t prob;
    m = 0;
    /* Find the internal node with the largest probability. */
    for (i = 1; i < size; i++) {
      if (tree_node_cmp(symb[next[i]], symb[next[m]]) > 0) m = i;
    }
    i = next[m];
    memmove(&next[m], &next[m + 1], sizeof(*next) * (size - (m + 1)));
    size--;
    /* Split this symbol into two symbols */
    n = symb[i];
    j = n.index;
    prob = probs[j >> 1];
    /* Left */
    n.index = tree[j];
    n.path <<= 1;
    n.len++;
    n.probs[n.len - 1] = prob;
    symb[nodes] = n;
    if (n.index > 0) {
      next[size++] = nodes;
    }
    /* Right */
    n.index = tree[j + 1];
    n.path += 1;
    n.probs[n.len - 1] = 256 - prob;
    symb[nodes + 1] = n;
    if (n.index > 0) {
      next[size++] = nodes + 1;
    }
    symb[i].prob = prob;
    symb[i].l = nodes;
    symb[i].r = nodes + 1;
    nodes += 2;
    nsymbs++;
  }
  /* Compute the probabilities of each symbol in Q15 */
  tree_node_compute_probs(symb, 0, CDF_PROB_TOP);
  /* Extract the cdf, index, path and length */
  tree_node_extract(symb, 0, 0, cdf, index, path, len);
  /* Convert to CDF */
  cdf[0] = AOM_ICDF(cdf[0]);
  for (i = 1; i < nsymbs; i++) {
    cdf[i] = AOM_ICDF(AOM_ICDF(cdf[i - 1]) + cdf[i]);
  }
// Store symbol count at the end of the CDF
#if CONFIG_EC_ADAPT
  cdf[nsymbs] = 0;
#endif
  return nsymbs;
}

/* This code assumes that tree contains as unique leaf nodes the integer values
    0 to len - 1 and produces the forward and inverse mapping tables in ind[]
    and inv[] respectively. */
static void tree_to_index(int *stack_index, int *ind, int *inv,
                          const aom_tree_index *tree, int value, int index) {
  value *= 2;

  do {
    const aom_tree_index content = tree[index];
    ++index;
    if (content <= 0) {
      inv[*stack_index] = -content;
      ind[-content] = *stack_index;
      ++(*stack_index);
    } else {
      tree_to_index(stack_index, ind, inv, tree, value, content);
    }
  } while (++value & 1);
}

void av1_indices_from_tree(int *ind, int *inv, const aom_tree_index *tree) {
  int stack_index = 0;
  tree_to_index(&stack_index, ind, inv, tree, 0, 0);
}
#endif