FFmpeg/libavcodec/put_golomb.h

/*
 * exp golomb vlc writing stuff
 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
 * 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
 * @brief
 *     exp golomb vlc writing stuff
 * @author Michael Niedermayer <michaelni@gmx.at> and Alex Beregszaszi
 */

#ifndef AVCODEC_PUT_GOLOMB_H
#define AVCODEC_PUT_GOLOMB_H

#include <stdint.h>
#include "put_bits.h"

extern const uint8_t ff_ue_golomb_len[256];

/**
 * write unsigned exp golomb code. 2^16 - 2 at most
 */
static inline void set_ue_golomb(PutBitContext *pb, int i)
{
    av_assert2(i >= 0);
    av_assert2(i <= 0xFFFE);

    if (i < 256)
        put_bits(pb, ff_ue_golomb_len[i], i + 1);
    else {
        int e = av_log2(i + 1);
        put_bits(pb, 2 * e + 1, i + 1);
    }
}

/**
 * write unsigned exp golomb code. 2^32-2 at most.
 */
static inline void set_ue_golomb_long(PutBitContext *pb, uint32_t i)
{
    av_assert2(i <= (UINT32_MAX - 1));

    if (i < 256)
        put_bits(pb, ff_ue_golomb_len[i], i + 1);
    else {
        int e = av_log2(i + 1);
        put_bits64(pb, 2 * e + 1, i + 1);
    }
}

/**
 * write truncated unsigned exp golomb code.
 */
static inline void set_te_golomb(PutBitContext *pb, int i, int range)
{
    av_assert2(range >= 1);
    av_assert2(i <= range);

    if (range == 2)
        put_bits(pb, 1, i ^ 1);
    else
        set_ue_golomb(pb, i);
}

/**
 * write signed exp golomb code. 16 bits at most.
 */
static inline void set_se_golomb(PutBitContext *pb, int i)
{
    i = 2 * i - 1;
    if (i < 0)
        i ^= -1;    //FIXME check if gcc does the right thing
    set_ue_golomb(pb, i);
}

/**
 * write unsigned golomb rice code (ffv1).
 */
static inline void set_ur_golomb(PutBitContext *pb, int i, int k, int limit,
                                 int esc_len)
{
    int e;

    av_assert2(i >= 0);

    e = i >> k;
    if (e < limit)
        put_bits(pb, e + k + 1, (1 << k) + av_mod_uintp2(i, k));
    else
        put_bits(pb, limit + esc_len, i - limit + 1);
}

/**
 * write unsigned golomb rice code (jpegls).
 */
static inline void set_ur_golomb_jpegls(PutBitContext *pb, int i, int k,
                                        int limit, int esc_len)
{
    int e;

    av_assert2(i >= 0);

    e = (i >> k) + 1;
    if (e < limit) {
        while (e > 31) {
            put_bits(pb, 31, 0);
            e -= 31;
        }
        put_bits(pb, e, 1);
        if (k)
            put_sbits(pb, k, i);
    } else {
        while (limit > 31) {
            put_bits(pb, 31, 0);
            limit -= 31;
        }
        put_bits(pb, limit, 1);
        put_bits(pb, esc_len, i - 1);
    }
}

/**
 * write signed golomb rice code (ffv1).
 */
static inline void set_sr_golomb(PutBitContext *pb, int i, int k, int limit,
                                 int esc_len)
{
    int v;

    v  = -2 * i - 1;
    v ^= (v >> 31);

    set_ur_golomb(pb, v, k, limit, esc_len);
}

#endif /* AVCODEC_PUT_GOLOMB_H */