xref: /third_party/ffmpeg/libavcodec/vp56rac.c (revision cabdff1a) 
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 "vp56.h"
26
27const uint8_t ff_vp56_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
42int ff_vp56_init_range_decoder(VP56RangeCoder *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}
54