apps/codecs/libffmpegFLAC/golomb.h

   1 /*
   2  * exp golomb vlc stuff
   3  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
   4  * Copyright (c) 2004 Alex Beregszaszi
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  *
  20  */
  21
  22 #include <limits.h>
  23 #include "codeclib.h"
  24
  25 /**
  26  * @file golomb.h
  27  * @brief
  28  *     exp golomb vlc stuff
  29  * @author Michael Niedermayer <michaelni@gmx.at> and Alex Beregszaszi
  30  */
  31
  32
  33 /**
  34  * read unsigned golomb rice code (jpegls).
  35  */
  36 static inline int get_ur_golomb_jpegls(GetBitContext *gb, int k, int limit, int esc_len){
  37     unsigned int buf;
  38     int log;
  39
  40     OPEN_READER(re, gb);
  41     UPDATE_CACHE(re, gb);
  42     buf=GET_CACHE(re, gb);
  43
  44     log= av_log2(buf);
  45
  46     if(log - k >= 32-MIN_CACHE_BITS+(MIN_CACHE_BITS==32) && 32-log < limit){
  47         buf >>= log - k;
  48         buf += (30-log)<<k;
  49         LAST_SKIP_BITS(re, gb, 32 + k - log);
  50         CLOSE_READER(re, gb);
  51
  52         return buf;
  53     }else{
  54         int i;
  55         for(i=0; SHOW_UBITS(re, gb, 1) == 0; i++){
  56             LAST_SKIP_BITS(re, gb, 1);
  57             UPDATE_CACHE(re, gb);
  58         }
  59         SKIP_BITS(re, gb, 1);
  60
  61         if(i < limit - 1){
  62             if(k){
  63                 buf = SHOW_UBITS(re, gb, k);
  64                 LAST_SKIP_BITS(re, gb, k);
  65             }else{
  66                 buf=0;
  67             }
  68
  69             CLOSE_READER(re, gb);
  70             return buf + (i<<k);
  71         }else if(i == limit - 1){
  72             buf = SHOW_UBITS(re, gb, esc_len);
  73             LAST_SKIP_BITS(re, gb, esc_len);
  74             CLOSE_READER(re, gb);
  75
  76             return buf + 1;
  77         }else
  78             return -1;
  79     }
  80 }
  81
  82 /**
  83  * read signed golomb rice code (flac).
  84  */
  85 static inline int get_sr_golomb_flac(GetBitContext *gb, int k, int limit, int esc_len){
  86     int v= get_ur_golomb_jpegls(gb, k, limit, esc_len);
  87     return (v>>1) ^ -(v&1);
  88 }
  89
  90 /**
  91  * read unsigned golomb rice code (shorten).
  92  */
  93 #define get_ur_golomb_shorten(gb, k) get_ur_golomb_jpegls(gb, k, INT_MAX, 0)
  94 /*
  95 static inline unsigned int get_ur_golomb_shorten(GetBitContext *gb, int k){
  96     return get_ur_golomb_jpegls(gb, k, INT_MAX, 0);
  97 }
  98 */
  99
 100 /**
 101  * read signed golomb rice code (shorten).
 102  */
 103 static inline int get_sr_golomb_shorten(GetBitContext* gb, int k)
 104 {
 105     int uvar = get_ur_golomb_jpegls(gb, k + 1, INT_MAX, 0);
 106     if (uvar & 1)
 107         return ~(uvar >> 1);
 108     else
 109         return uvar >> 1;
 110 }