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author | Dave Chapman <dave@dchapman.com> | 2009-05-09 01:04:20 +0000 |
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committer | Dave Chapman <dave@dchapman.com> | 2009-05-09 01:04:20 +0000 |
commit | 69db01e72f2de91d35703919bfc9d0700df83e85 (patch) | |
tree | 18a8d01dc3df13c5dc51b813d7ce70e6bec79704 /apps/codecs/libcook/libavutil/lfg.h | |
parent | 681a774472eded71f7a82fbfa4c3591f3f98d209 (diff) | |
download | rockbox-69db01e72f2de91d35703919bfc9d0700df83e85.tar.gz rockbox-69db01e72f2de91d35703919bfc9d0700df83e85.zip |
Initial commit of the minimal set of ffmpeg (r18079) files required for Cook (realaudio) decoding. These are the unmodified versions from ffmpeg, committed as a base for future changes.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@20882 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'apps/codecs/libcook/libavutil/lfg.h')
-rw-r--r-- | apps/codecs/libcook/libavutil/lfg.h | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/apps/codecs/libcook/libavutil/lfg.h b/apps/codecs/libcook/libavutil/lfg.h new file mode 100644 index 0000000000..3250c18e79 --- /dev/null +++ b/apps/codecs/libcook/libavutil/lfg.h | |||
@@ -0,0 +1,54 @@ | |||
1 | /* | ||
2 | * Lagged Fibonacci PRNG | ||
3 | * Copyright (c) 2008 Michael Niedermayer | ||
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 | #ifndef AVUTIL_LFG_H | ||
23 | #define AVUTIL_LFG_H | ||
24 | |||
25 | typedef struct { | ||
26 | unsigned int state[64]; | ||
27 | int index; | ||
28 | } AVLFG; | ||
29 | |||
30 | void av_lfg_init(AVLFG *c, unsigned int seed); | ||
31 | |||
32 | /** | ||
33 | * Gets the next random unsigned 32-bit number using an ALFG. | ||
34 | * | ||
35 | * Please also consider a simple LCG like state= state*1664525+1013904223, | ||
36 | * it may be good enough and faster for your specific use case. | ||
37 | */ | ||
38 | static inline unsigned int av_lfg_get(AVLFG *c){ | ||
39 | c->state[c->index & 63] = c->state[(c->index-24) & 63] + c->state[(c->index-55) & 63]; | ||
40 | return c->state[c->index++ & 63]; | ||
41 | } | ||
42 | |||
43 | /** | ||
44 | * Gets the next random unsigned 32-bit number using a MLFG. | ||
45 | * | ||
46 | * Please also consider av_lfg_get() above, it is faster. | ||
47 | */ | ||
48 | static inline unsigned int av_mlfg_get(AVLFG *c){ | ||
49 | unsigned int a= c->state[(c->index-55) & 63]; | ||
50 | unsigned int b= c->state[(c->index-24) & 63]; | ||
51 | return c->state[c->index++ & 63] = 2*a*b+a+b; | ||
52 | } | ||
53 | |||
54 | #endif /* AVUTIL_LFG_H */ | ||