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ffmpeg / libavcodec / golomb.h @ 0da71265

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/*
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 * exp golomb vlc stuff
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 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
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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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/**
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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>
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 */
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extern const uint8_t ff_golomb_vlc_len[512];
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extern const uint8_t ff_ue_golomb_vlc_code[512];
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extern const  int8_t ff_se_golomb_vlc_code[512];
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extern const uint8_t ff_ue_golomb_len[256];
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 /**
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 * read unsigned exp golomb code.
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 */
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static inline int get_ue_golomb(GetBitContext *gb){
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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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    if(buf >= (1<<27)){
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        buf >>= 32 - 9;
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        LAST_SKIP_BITS(re, gb, ff_golomb_vlc_len[buf]);
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        CLOSE_READER(re, gb);
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        return ff_ue_golomb_vlc_code[buf];
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    }else{
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        log= 2*av_log2(buf) - 31;
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        buf>>= log;
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        buf--;
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        LAST_SKIP_BITS(re, gb, 32 - log);
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        CLOSE_READER(re, gb);
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        return buf;
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    }
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}
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/**
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 * read unsigned truncated exp golomb code.
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 */
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static inline int get_te0_golomb(GetBitContext *gb, int range){
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    assert(range >= 1);
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    if(range==1)      return 0;
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    else if(range==2) return get_bits1(gb);
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    else              return get_ue_golomb(gb);
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}
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/**
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 * read unsigned truncated exp golomb code.
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 */
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static inline int get_te_golomb(GetBitContext *gb, int range){
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    assert(range >= 1);
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    if(range==2) return get_bits1(gb);
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    else         return get_ue_golomb(gb);
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}
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/**
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 * read signed exp golomb code.
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 */
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static inline int get_se_golomb(GetBitContext *gb){
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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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    if(buf >= (1<<27)){
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        buf >>= 32 - 9;
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        LAST_SKIP_BITS(re, gb, ff_golomb_vlc_len[buf]);
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        CLOSE_READER(re, gb);
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        return ff_se_golomb_vlc_code[buf];
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    }else{
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        log= 2*av_log2(buf) - 31;
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        buf>>= log;
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        LAST_SKIP_BITS(re, gb, 32 - log);
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        CLOSE_READER(re, gb);
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        if(buf&1) buf= -(buf>>1);
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        else      buf=  (buf>>1);
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        return buf;
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    }
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}
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#ifdef TRACE
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static inline int get_ue(GetBitContext *s, char *file, char *func, int line){
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    int show= show_bits(s, 24);
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    int pos= get_bits_count(s);
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    int i= get_ue_golomb(s);
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    int len= get_bits_count(s) - pos;
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    int bits= show>>(24-len);
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    print_bin(bits, len);
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    printf("%5d %2d %3d ue  @%5d in %s %s:%d\n", bits, len, i, pos, file, func, line);
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    return i;
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}
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static inline int get_se(GetBitContext *s, char *file, char *func, int line){
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    int show= show_bits(s, 24);
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    int pos= get_bits_count(s);
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    int i= get_se_golomb(s);
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    int len= get_bits_count(s) - pos;
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    int bits= show>>(24-len);
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    print_bin(bits, len);
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    printf("%5d %2d %3d se  @%5d in %s %s:%d\n", bits, len, i, pos, file, func, line);
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    return i;
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}
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static inline int get_te(GetBitContext *s, int r, char *file, char *func, int line){
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    int show= show_bits(s, 24);
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    int pos= get_bits_count(s);
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    int i= get_te0_golomb(s, r);
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    int len= get_bits_count(s) - pos;
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    int bits= show>>(24-len);
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    print_bin(bits, len);
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    printf("%5d %2d %3d te  @%5d in %s %s:%d\n", bits, len, i, pos, file, func, line);
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    return i;
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}
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#define get_ue_golomb(a) get_ue(a, __FILE__, __PRETTY_FUNCTION__, __LINE__)
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#define get_se_golomb(a) get_se(a, __FILE__, __PRETTY_FUNCTION__, __LINE__)
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#define get_te_golomb(a, r) get_te(a, r, __FILE__, __PRETTY_FUNCTION__, __LINE__)
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#define get_te0_golomb(a, r) get_te(a, r, __FILE__, __PRETTY_FUNCTION__, __LINE__)
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#endif
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/**
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 * write unsigned exp golomb code.
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 */
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static inline void set_ue_golomb(PutBitContext *pb, int i){
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    int e;
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    assert(i>=0);
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#if 0
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    if(i=0){
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        put_bits(pb, 1, 1);
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        return;
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    }
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#endif
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    if(i<256)
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        put_bits(pb, ff_ue_golomb_len[i], i+1);
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    else{
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        e= av_log2(i+1);
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        put_bits(pb, 2*e+1, i+1);
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    }
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}
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/**
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 * write truncated unsigned exp golomb code.
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 */
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static inline void set_te_golomb(PutBitContext *pb, int i, int range){
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    assert(range >= 1);
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    assert(i<=range);
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    if(range==2) put_bits(pb, 1, i);
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    else         set_ue_golomb(pb, i);
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}
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/**
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 * write signed exp golomb code.
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 */
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static inline void set_se_golomb(PutBitContext *pb, int i){
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#if 0 
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    if(i<=0) i= -2*i;
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    else     i=  2*i-1;
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#elif 1
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    i= 2*i-1;
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    if(i<0) i^= -1; //FIXME check if gcc does the right thing
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#else
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    i= 2*i-1;
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    i^= (i>>31);
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#endif
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    set_ue_golomb(pb, i);
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}