vp8/encoder/boolhuff.c

   1 /*
   2  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11
  12 #include "boolhuff.h"
  13 #include "blockd.h"
  14
  15
  16
  17 #if defined(SECTIONBITS_OUTPUT)
  18 unsigned __int64 Sectionbits[500];
  19
  20 #endif
  21
  22 #ifdef ENTROPY_STATS
  23 unsigned int active_section = 0;
  24 #endif
  25
  26 const unsigned int vp8_prob_cost[256] =
  27 {
  28     2047, 2047, 1791, 1641, 1535, 1452, 1385, 1328, 1279, 1235, 1196, 1161, 1129, 1099, 1072, 1046,
  29     1023, 1000,  979,  959,  940,  922,  905,  889,  873,  858,  843,  829,  816,  803,  790,  778,
  30     767,  755,  744,  733,  723,  713,  703,  693,  684,  675,  666,  657,  649,  641,  633,  625,
  31     617,  609,  602,  594,  587,  580,  573,  567,  560,  553,  547,  541,  534,  528,  522,  516,
  32     511,  505,  499,  494,  488,  483,  477,  472,  467,  462,  457,  452,  447,  442,  437,  433,
  33     428,  424,  419,  415,  410,  406,  401,  397,  393,  389,  385,  381,  377,  373,  369,  365,
  34     361,  357,  353,  349,  346,  342,  338,  335,  331,  328,  324,  321,  317,  314,  311,  307,
  35     304,  301,  297,  294,  291,  288,  285,  281,  278,  275,  272,  269,  266,  263,  260,  257,
  36     255,  252,  249,  246,  243,  240,  238,  235,  232,  229,  227,  224,  221,  219,  216,  214,
  37     211,  208,  206,  203,  201,  198,  196,  194,  191,  189,  186,  184,  181,  179,  177,  174,
  38     172,  170,  168,  165,  163,  161,  159,  156,  154,  152,  150,  148,  145,  143,  141,  139,
  39     137,  135,  133,  131,  129,  127,  125,  123,  121,  119,  117,  115,  113,  111,  109,  107,
  40     105,  103,  101,   99,   97,   95,   93,   92,   90,   88,   86,   84,   82,   81,   79,   77,
  41     75,   73,   72,   70,   68,   66,   65,   63,   61,   60,   58,   56,   55,   53,   51,   50,
  42     48,   46,   45,   43,   41,   40,   38,   37,   35,   33,   32,   30,   29,   27,   25,   24,
  43     22,   21,   19,   18,   16,   15,   13,   12,   10,    9,    7,    6,    4,    3,    1,   1
  44 };
  45
  46 void vp8_start_encode(BOOL_CODER *br, unsigned char *source)
  47 {
  48
  49     br->lowvalue = 0;
  50     br->range    = 255;
  51     br->value    = 0;
  52     br->count    = -24;
  53     br->buffer   = source;
  54     br->pos      = 0;
  55 }
  56
  57 void vp8_stop_encode(BOOL_CODER *br)
  58 {
  59     int i;
  60
  61     for (i = 0; i < 32; i++)
  62         vp8_encode_bool(br, 0, 128);
  63 }
  64
  65 DECLARE_ALIGNED(16, static const unsigned int, norm[256]) =
  66 {
  67     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,
  68     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,
  69     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,
  70     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,
  71     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,
  72     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,
  73     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,
  74     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
  75 };
  76
  77 void vp8_encode_bool(BOOL_CODER *br, int bit, int probability)
  78 {
  79     unsigned int split;
  80     int count = br->count;
  81     unsigned int range = br->range;
  82     unsigned int lowvalue = br->lowvalue;
  83     register unsigned int shift;
  84
  85 #ifdef ENTROPY_STATS
  86 #if defined(SECTIONBITS_OUTPUT)
  87
  88     if (bit)
  89         Sectionbits[active_section] += vp8_prob_cost[255-probability];
  90     else
  91         Sectionbits[active_section] += vp8_prob_cost[probability];
  92
  93 #endif
  94 #endif
  95
  96     split = 1 + (((range - 1) * probability) >> 8);
  97
  98     range = split;
  99
 100     if (bit)
 101     {
 102         lowvalue += split;
 103         range = br->range - split;
 104     }
 105
 106     shift = norm[range];
 107
 108     range <<= shift;
 109     count += shift;
 110
 111     if (count >= 0)
 112     {
 113         int offset = shift - count;
 114
 115         if ((lowvalue << (offset - 1)) & 0x80000000)
 116         {
 117             int x = br->pos - 1;
 118
 119             while (x >= 0 && br->buffer[x] == 0xff)
 120             {
 121                 br->buffer[x] = (unsigned char)0;
 122                 x--;
 123             }
 124
 125             br->buffer[x] += 1;
 126         }
 127
 128         br->buffer[br->pos++] = (lowvalue >> (24 - offset));
 129         lowvalue <<= offset;
 130         shift = count;
 131         lowvalue &= 0xffffff;
 132         count -= 8 ;
 133     }
 134
 135     lowvalue <<= shift;
 136     br->count = count;
 137     br->lowvalue = lowvalue;
 138     br->range = range;
 139 }
 140
 141 void vp8_encode_value(BOOL_CODER *br, int data, int bits)
 142 {
 143     int bit;
 144
 145     for (bit = bits - 1; bit >= 0; bit--)
 146         vp8_encode_bool(br, (1 & (data >> bit)), 0x80);
 147
 148 }