src/third_party/libvpx/vp9/encoder/vp9_cost.c

/*
 *  Copyright (c) 2014 The WebM project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */
#include <assert.h>

#include "vp9/encoder/vp9_cost.h"

/* round(-log2(i/256.) * (1 << VP9_PROB_COST_SHIFT))
   Begins with a bogus entry for simpler addressing. */
const uint16_t vp9_prob_cost[256] = {
    4096, 4096, 3584, 3284, 3072, 2907, 2772, 2659, 2560, 2473, 2395, 2325,
    2260, 2201, 2147, 2096, 2048, 2003, 1961, 1921, 1883, 1847, 1813, 1780,
    1748, 1718, 1689, 1661, 1635, 1609, 1584, 1559, 1536, 1513, 1491, 1470,
    1449, 1429, 1409, 1390, 1371, 1353, 1335, 1318, 1301, 1284, 1268, 1252,
    1236, 1221, 1206, 1192, 1177, 1163, 1149, 1136, 1123, 1110, 1097, 1084,
    1072, 1059, 1047, 1036, 1024, 1013, 1001, 990,  979,  968,  958,  947,
    937,  927,  917,  907,  897,  887,  878,  868,  859,  850,  841,  832,
    823,  814,  806,  797,  789,  780,  772,  764,  756,  748,  740,  732,
    724,  717,  709,  702,  694,  687,  680,  673,  665,  658,  651,  644,
    637,  631,  624,  617,  611,  604,  598,  591,  585,  578,  572,  566,
    560,  554,  547,  541,  535,  530,  524,  518,  512,  506,  501,  495,
    489,  484,  478,  473,  467,  462,  456,  451,  446,  441,  435,  430,
    425,  420,  415,  410,  405,  400,  395,  390,  385,  380,  375,  371,
    366,  361,  356,  352,  347,  343,  338,  333,  329,  324,  320,  316,
    311,  307,  302,  298,  294,  289,  285,  281,  277,  273,  268,  264,
    260,  256,  252,  248,  244,  240,  236,  232,  228,  224,  220,  216,
    212,  209,  205,  201,  197,  194,  190,  186,  182,  179,  175,  171,
    168,  164,  161,  157,  153,  150,  146,  143,  139,  136,  132,  129,
    125,  122,  119,  115,  112,  109,  105,  102,  99,   95,   92,   89,
    86,   82,   79,   76,   73,   70,   66,   63,   60,   57,   54,   51,
    48,   45,   42,   38,   35,   32,   29,   26,   23,   20,   18,   15,
    12,   9,    6,    3};

static void cost(int *costs, vpx_tree tree, const vpx_prob *probs,
                 int i, int c) {
  const vpx_prob prob = probs[i / 2];
  int b;

  assert(prob != 0);
  for (b = 0; b <= 1; ++b) {
    const int cc = c + vp9_cost_bit(prob, b);
    const vpx_tree_index ii = tree[i + b];

    if (ii <= 0)
      costs[-ii] = cc;
    else
      cost(costs, tree, probs, ii, cc);
  }
}

void vp9_cost_tokens(int *costs, const vpx_prob *probs, vpx_tree tree) {
  cost(costs, tree, probs, 0, 0);
}

void vp9_cost_tokens_skip(int *costs, const vpx_prob *probs, vpx_tree tree) {
  assert(tree[0] <= 0 && tree[1] > 0);

  costs[-tree[0]] = vp9_cost_bit(probs[0], 0);
  cost(costs, tree, probs, 2, 0);
}