golomb.h

This the source release kit for the following system configuration(s): - AMD Alchemy(TM) DBAu1200(

/*
 * exp golomb vlc stuff
 * Copyright (c) 2003 Michael Niedermayer <[e-mail]>
 * Copyright (c) 2004 Alex Beregszaszi
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 */

/**
 * @file golomb.h
 * @brief
 *     exp golomb vlc stuff
 * @author Michael Niedermayer <[e-mail]> and Alex Beregszaszi
 */

#define INVALID_VLC           0x80000000

extern const uint8_t ff_golomb_vlc_len[512];
extern const uint8_t ff_ue_golomb_vlc_code[512];
extern const  int8_t ff_se_golomb_vlc_code[512];

extern unsigned int g_buf;

 /**
 * read unsigned exp golomb code.
 */
#define GET_UE_GOLOMB(gb)\
{\
    int log;\
\
    OPEN_READER(re, gb);\
    UPDATE_CACHE(re, gb);\
    g_buf=GET_CACHE(re, gb);\
\
    if(g_buf >= (1<<27))\
 {\
        g_buf >>= 32 - 9;\
        LAST_SKIP_BITS(re, gb, ff_golomb_vlc_len[g_buf]);\
        CLOSE_READER(re, gb);\
\
        g_buf = ff_ue_golomb_vlc_code[g_buf];\
    }\
 else\
 {\
        log= 2*av_log2(g_buf) - 31;\
        g_buf>>= log;\
        g_buf--;\
        LAST_SKIP_BITS(re, gb, 32 - log);\
        CLOSE_READER(re, gb);\
    }\
}

/**
 * read unsigned truncated exp golomb code.
 */
static always_inline int get_te0_golomb(GetBitContext *gb, int range)
{
    assert(range >= 1);

    if(range==1)      return 0;
    else if(range==2) return get_bits1(gb)^1;
    else
 {
  GET_UE_GOLOMB(gb);
  return g_buf;
 }
}

/**
 * read signed exp golomb code.
 */
static always_inline int get_se_golomb(GetBitContext *gb)
{
    unsigned int buf;
    int log;

    OPEN_READER(re, gb);
    UPDATE_CACHE(re, gb);
    buf=GET_CACHE(re, gb);

    if(buf >= (1<<27)){
        buf >>= 32 - 9;
        LAST_SKIP_BITS(re, gb, ff_golomb_vlc_len[buf]);
        CLOSE_READER(re, gb);

        return ff_se_golomb_vlc_code[buf];
    }else{
        log= (av_log2(buf)<<1) - 31;
        buf>>= log;

        LAST_SKIP_BITS(re, gb, 32 - log);
        CLOSE_READER(re, gb);

        if(buf&1) buf= -((int)(buf>>1));
        else      buf=  (buf>>1);

        return buf;
    }
}