The Tor Browser / file comparison
comparison: media/libtheora/lib/bitpack.c
media/libtheora/lib/bitpack.c
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
equal
deleted
inserted
replaced
| -1:000000000000 | 0:3d72cedc8fc1 |
|---|---|
| 1 /******************************************************************** | |
| 2 * * | |
| 3 * THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE. * | |
| 4 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS * | |
| 5 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE * | |
| 6 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. * | |
| 7 * * | |
| 8 * THE OggTheora SOURCE CODE IS (C) COPYRIGHT 1994-2009 * | |
| 9 * by the Xiph.Org Foundation and contributors http://www.xiph.org/ * | |
| 10 * * | |
| 11 ******************************************************************** | |
| 12 | |
| 13 function: packing variable sized words into an octet stream | |
| 14 last mod: $Id: bitpack.c 17410 2010-09-21 21:53:48Z tterribe $ | |
| 15 | |
| 16 ********************************************************************/ | |
| 17 #include <string.h> | |
| 18 #include <stdlib.h> | |
| 19 #include "bitpack.h" | |
| 20 | |
| 21 /*We're 'MSb' endian; if we write a word but read individual bits, | |
| 22 then we'll read the MSb first.*/ | |
| 23 | |
| 24 void oc_pack_readinit(oc_pack_buf *_b,unsigned char *_buf,long _bytes){ | |
| 25 memset(_b,0,sizeof(*_b)); | |
| 26 _b->ptr=_buf; | |
| 27 _b->stop=_buf+_bytes; | |
| 28 } | |
| 29 | |
| 30 static oc_pb_window oc_pack_refill(oc_pack_buf *_b,int _bits){ | |
| 31 const unsigned char *ptr; | |
| 32 const unsigned char *stop; | |
| 33 oc_pb_window window; | |
| 34 int available; | |
| 35 unsigned shift; | |
| 36 stop=_b->stop; | |
| 37 ptr=_b->ptr; | |
| 38 window=_b->window; | |
| 39 available=_b->bits; | |
| 40 shift=OC_PB_WINDOW_SIZE-available; | |
| 41 while(7<shift&&ptr<stop){ | |
| 42 shift-=8; | |
| 43 window|=(oc_pb_window)*ptr++<<shift; | |
| 44 } | |
| 45 _b->ptr=ptr; | |
| 46 available=OC_PB_WINDOW_SIZE-shift; | |
| 47 if(_bits>available){ | |
| 48 if(ptr>=stop){ | |
| 49 _b->eof=1; | |
| 50 available=OC_LOTS_OF_BITS; | |
| 51 } | |
| 52 else window|=*ptr>>(available&7); | |
| 53 } | |
| 54 _b->bits=available; | |
| 55 return window; | |
| 56 } | |
| 57 | |
| 58 int oc_pack_look1(oc_pack_buf *_b){ | |
| 59 oc_pb_window window; | |
| 60 int available; | |
| 61 window=_b->window; | |
| 62 available=_b->bits; | |
| 63 if(available<1)_b->window=window=oc_pack_refill(_b,1); | |
| 64 return window>>OC_PB_WINDOW_SIZE-1; | |
| 65 } | |
| 66 | |
| 67 void oc_pack_adv1(oc_pack_buf *_b){ | |
| 68 _b->window<<=1; | |
| 69 _b->bits--; | |
| 70 } | |
| 71 | |
| 72 /*Here we assume that 0<=_bits&&_bits<=32.*/ | |
| 73 long oc_pack_read_c(oc_pack_buf *_b,int _bits){ | |
| 74 oc_pb_window window; | |
| 75 int available; | |
| 76 long result; | |
| 77 window=_b->window; | |
| 78 available=_b->bits; | |
| 79 if(_bits==0)return 0; | |
| 80 if(available<_bits){ | |
| 81 window=oc_pack_refill(_b,_bits); | |
| 82 available=_b->bits; | |
| 83 } | |
| 84 result=window>>OC_PB_WINDOW_SIZE-_bits; | |
| 85 available-=_bits; | |
| 86 window<<=1; | |
| 87 window<<=_bits-1; | |
| 88 _b->window=window; | |
| 89 _b->bits=available; | |
| 90 return result; | |
| 91 } | |
| 92 | |
| 93 int oc_pack_read1_c(oc_pack_buf *_b){ | |
| 94 oc_pb_window window; | |
| 95 int available; | |
| 96 int result; | |
| 97 window=_b->window; | |
| 98 available=_b->bits; | |
| 99 if(available<1){ | |
| 100 window=oc_pack_refill(_b,1); | |
| 101 available=_b->bits; | |
| 102 } | |
| 103 result=window>>OC_PB_WINDOW_SIZE-1; | |
| 104 available--; | |
| 105 window<<=1; | |
| 106 _b->window=window; | |
| 107 _b->bits=available; | |
| 108 return result; | |
| 109 } | |
| 110 | |
| 111 long oc_pack_bytes_left(oc_pack_buf *_b){ | |
| 112 if(_b->eof)return -1; | |
| 113 return _b->stop-_b->ptr+(_b->bits>>3); | |
| 114 } |
