2 * Lagarith range decoder
3 * Copyright (c) 2009 Nathan Caldwell <saintdev (at) gmail.com>
4 * Copyright (c) 2009 David Conrad
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25 * Lagarith range decoder
26 * @author Nathan Caldwell
27 * @author David Conrad
31 #include "lagarithrac.h"
33 void ff_lag_rac_init(lag_rac
*l
, GetBitContext
*gb
, int length
)
37 /* According to reference decoder "1st byte is garbage",
38 * however, it gets skipped by the call to align_get_bits()
41 left
= get_bits_left(gb
) >> 3;
43 l
->bytestream
= gb
->buffer
+ get_bits_count(gb
) / 8;
44 l
->bytestream_end
= l
->bytestream_start
+ left
;
47 l
->low
= *l
->bytestream
>> 1;
48 l
->hash_shift
= FFMAX((int)l
->scale
- 10, 0);
50 for (i
= j
= 0; i
< 1024; i
++) {
51 unsigned r
= i
<< l
->hash_shift
;
52 while (l
->prob
[j
+ 1] <= r
)