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author | henry <henry@b3059339-0415-0410-9bf9-f77b7e298cf2> | 2004-12-30 12:11:32 +0000 |
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committer | henry <henry@b3059339-0415-0410-9bf9-f77b7e298cf2> | 2004-12-30 12:11:32 +0000 |
commit | fc91fed21ea71c50273c7c09f88e8d634c1e444e (patch) | |
tree | a4b1344270267c9d16eef135488049bd4e9a96f9 /tremor/bitwise.c | |
parent | dbbe18f4500c2707f2e9c0967c7b79312edecd3d (diff) | |
download | mpv-fc91fed21ea71c50273c7c09f88e8d634c1e444e.tar.bz2 mpv-fc91fed21ea71c50273c7c09f88e8d634c1e444e.tar.xz |
internal Tremor decoder for Ogg/Vorbis
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@14281 b3059339-0415-0410-9bf9-f77b7e298cf2
Diffstat (limited to 'tremor/bitwise.c')
-rw-r--r-- | tremor/bitwise.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/tremor/bitwise.c b/tremor/bitwise.c new file mode 100644 index 0000000000..4782ee053b --- /dev/null +++ b/tremor/bitwise.c @@ -0,0 +1,144 @@ +/******************************************************************** + * * + * THIS FILE IS PART OF THE OggVorbis 'TREMOR' CODEC SOURCE CODE. * + * * + * THE OggVorbis 'TREMOR' SOURCE CODE IS (C) COPYRIGHT 1994-2002 * + * BY THE Xiph.Org FOUNDATION http://www.xiph.org/ * + * ALL REDISTRIBUTION RIGHTS RESERVED. * + * * + ******************************************************************** + + function: packing variable sized words into an octet stream + + ********************************************************************/ + +/* We're 'LSb' endian; if we write a word but read individual bits, + then we'll read the lsb first */ + +#include <string.h> +#include <stdlib.h> +#include "ogg.h" + +#define BUFFER_INCREMENT 256 + +static unsigned long mask[]= +{0x00000000,0x00000001,0x00000003,0x00000007,0x0000000f, + 0x0000001f,0x0000003f,0x0000007f,0x000000ff,0x000001ff, + 0x000003ff,0x000007ff,0x00000fff,0x00001fff,0x00003fff, + 0x00007fff,0x0000ffff,0x0001ffff,0x0003ffff,0x0007ffff, + 0x000fffff,0x001fffff,0x003fffff,0x007fffff,0x00ffffff, + 0x01ffffff,0x03ffffff,0x07ffffff,0x0fffffff,0x1fffffff, + 0x3fffffff,0x7fffffff,0xffffffff }; + +void oggpack_readinit(oggpack_buffer *b,unsigned char *buf,int bytes){ + memset(b,0,sizeof(*b)); + b->buffer=b->ptr=buf; + b->storage=bytes; +} + +/* Read in bits without advancing the bitptr; bits <= 32 */ +long oggpack_look(oggpack_buffer *b,int bits){ + unsigned long ret; + unsigned long m=mask[bits]; + + bits+=b->endbit; + + if(b->endbyte+4>=b->storage){ + /* not the main path */ + if(b->endbyte*8+bits>b->storage*8)return(-1); + } + + ret=b->ptr[0]>>b->endbit; + if(bits>8){ + ret|=b->ptr[1]<<(8-b->endbit); + if(bits>16){ + ret|=b->ptr[2]<<(16-b->endbit); + if(bits>24){ + ret|=b->ptr[3]<<(24-b->endbit); + if(bits>32 && b->endbit) + ret|=b->ptr[4]<<(32-b->endbit); + } + } + } + return(m&ret); +} + +long oggpack_look1(oggpack_buffer *b){ + if(b->endbyte>=b->storage)return(-1); + return((b->ptr[0]>>b->endbit)&1); +} + +void oggpack_adv(oggpack_buffer *b,int bits){ + bits+=b->endbit; + b->ptr+=bits/8; + b->endbyte+=bits/8; + b->endbit=bits&7; +} + +void oggpack_adv1(oggpack_buffer *b){ + if(++(b->endbit)>7){ + b->endbit=0; + b->ptr++; + b->endbyte++; + } +} + +/* bits <= 32 */ +long oggpack_read(oggpack_buffer *b,int bits){ + unsigned long ret; + unsigned long m=mask[bits]; + + bits+=b->endbit; + + if(b->endbyte+4>=b->storage){ + /* not the main path */ + ret=-1UL; + if(b->endbyte*8+bits>b->storage*8)goto overflow; + } + + ret=b->ptr[0]>>b->endbit; + if(bits>8){ + ret|=b->ptr[1]<<(8-b->endbit); + if(bits>16){ + ret|=b->ptr[2]<<(16-b->endbit); + if(bits>24){ + ret|=b->ptr[3]<<(24-b->endbit); + if(bits>32 && b->endbit){ + ret|=b->ptr[4]<<(32-b->endbit); + } + } + } + } + ret&=m; + + overflow: + + b->ptr+=bits/8; + b->endbyte+=bits/8; + b->endbit=bits&7; + return(ret); +} + +long oggpack_read1(oggpack_buffer *b){ + unsigned long ret; + + if(b->endbyte>=b->storage){ + /* not the main path */ + ret=-1UL; + goto overflow; + } + + ret=(b->ptr[0]>>b->endbit)&1; + + overflow: + + b->endbit++; + if(b->endbit>7){ + b->endbit=0; + b->ptr++; + b->endbyte++; + } + return(ret); +} + +#undef BUFFER_INCREMENT |