f40bfc9267
Change-Id: Id7f4717d51ed02d67cb9f9cb3c0ada4a81843f97 Reviewed-on: http://gerrit.rockbox.org/137 Reviewed-by: Nils Wallménius <nils@rockbox.org> Tested-by: Nils Wallménius <nils@rockbox.org>
110 lines
2.9 KiB
C
110 lines
2.9 KiB
C
/*
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* exp golomb vlc stuff
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* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
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* Copyright (c) 2004 Alex Beregszaszi
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <limits.h>
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#include "codeclib.h"
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/**
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* @file golomb.h
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* @brief
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* exp golomb vlc stuff
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* @author Michael Niedermayer <michaelni@gmx.at> and Alex Beregszaszi
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*/
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/**
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* read unsigned golomb rice code (jpegls).
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*/
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static inline int get_ur_golomb_jpegls(GetBitContext *gb, int k, int limit, int esc_len){
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unsigned int buf;
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int log;
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OPEN_READER(re, gb);
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UPDATE_CACHE(re, gb);
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buf=GET_CACHE(re, gb);
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log= av_log2(buf);
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if(log - k >= 32-MIN_CACHE_BITS+(MIN_CACHE_BITS==32) && 32-log < limit){
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buf >>= log - k;
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buf += (30-log)<<k;
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LAST_SKIP_BITS(re, gb, 32 + k - log);
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CLOSE_READER(re, gb);
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return buf;
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}else{
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int i;
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for(i=0; SHOW_UBITS(re, gb, 1) == 0; i++){
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LAST_SKIP_BITS(re, gb, 1);
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UPDATE_CACHE(re, gb);
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}
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SKIP_BITS(re, gb, 1);
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if(i < limit - 1){
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if(k){
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buf = SHOW_UBITS(re, gb, k);
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LAST_SKIP_BITS(re, gb, k);
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}else{
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buf=0;
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}
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CLOSE_READER(re, gb);
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return buf + (i<<k);
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}else if(i == limit - 1){
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buf = SHOW_UBITS(re, gb, esc_len);
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LAST_SKIP_BITS(re, gb, esc_len);
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CLOSE_READER(re, gb);
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return buf + 1;
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}else
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return -1;
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}
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}
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/**
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* read signed golomb rice code (flac).
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*/
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static inline int get_sr_golomb_flac(GetBitContext *gb, int k, int limit, int esc_len){
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int v= get_ur_golomb_jpegls(gb, k, limit, esc_len);
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return (v>>1) ^ -(v&1);
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}
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/**
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* read unsigned golomb rice code (shorten).
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*/
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#define get_ur_golomb_shorten(gb, k) get_ur_golomb_jpegls(gb, k, INT_MAX, 0)
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/*
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static inline unsigned int get_ur_golomb_shorten(GetBitContext *gb, int k){
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return get_ur_golomb_jpegls(gb, k, INT_MAX, 0);
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}
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*/
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/**
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* read signed golomb rice code (shorten).
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*/
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static inline int get_sr_golomb_shorten(GetBitContext* gb, int k)
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{
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int uvar = get_ur_golomb_jpegls(gb, k + 1, INT_MAX, 0);
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if (uvar & 1)
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return ~(uvar >> 1);
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else
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return uvar >> 1;
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}
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