libavcodec/vpx_rac.c

   1 /*
   2  * VP5/6/8 decoder
   3  * Copyright (c) 2010 Fiona Glaser <fiona@x264.com>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include <stdint.h>
  23 #include "libavutil/error.h"
  24 #include "bytestream.h"
  25 #include "vpx_rac.h"
  26
  27 const uint8_t ff_vpx_norm_shift[256]= {
  28  8,7,6,6,5,5,5,5,4,4,4,4,4,4,4,4,
  29  3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
  30  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
  31  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
  32  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
  33  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
  34  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
  35  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
  36  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,
  37  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,
  38  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,
  39  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,
  40 };
  41
  42 int ff_vpx_init_range_decoder(VPXRangeCoder *c, const uint8_t *buf, int buf_size)
  43 {
  44     c->high = 255;
  45     c->bits = -16;
  46     c->buffer = buf;
  47     c->end = buf + buf_size;
  48     c->end_reached = 0;
  49     if (buf_size < 1)
  50         return AVERROR_INVALIDDATA;
  51     c->code_word = bytestream_get_be24(&c->buffer);
  52     return 0;
  53 }