vp8/decoder/dboolhuff.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 "dboolhuff.h"
  13 #include "vpx_ports/mem.h"
  14 #include "vpx_mem/vpx_mem.h"
  15
  16 DECLARE_ALIGNED(16, const unsigned char, vp8dx_bitreader_norm[256]) =
  17 {
  18     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,
  19     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,
  20     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,
  21     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,
  22     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,
  23     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,
  24     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,
  25     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
  26 };
  27
  28
  29 int vp8dx_start_decode(BOOL_DECODER *br,
  30                        const unsigned char *source,
  31                        unsigned int source_sz)
  32 {
  33     br->user_buffer_end = source+source_sz;
  34     br->user_buffer     = source;
  35     br->value    = 0;
  36     br->count    = -8;
  37     br->range    = 255;
  38
  39     if (source_sz && !source)
  40         return 1;
  41
  42     /* Populate the buffer */
  43     vp8dx_bool_decoder_fill(br);
  44
  45     return 0;
  46 }
  47
  48
  49 void vp8dx_bool_decoder_fill(BOOL_DECODER *br)
  50 {
  51     const unsigned char *bufptr;
  52     const unsigned char *bufend;
  53     VP8_BD_VALUE         value;
  54     int                  count;
  55     bufend = br->user_buffer_end;
  56     bufptr = br->user_buffer;
  57     value = br->value;
  58     count = br->count;
  59
  60     VP8DX_BOOL_DECODER_FILL(count, value, bufptr, bufend);
  61
  62     br->user_buffer = bufptr;
  63     br->value = value;
  64     br->count = count;
  65 }