/*
 * 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
 */

#ifndef AVCODEC_GOLOMB_BS_H
#define AVCODEC_GOLOMB_BS_H

#include <stdint.h>

#include "bitstream.h"
#include "golomb_common.h"

/**
 * Read an unsigned Exp-Golomb code in the range 0 to 8190.
 *
 * @returns the read value or a negative error code.
 */
static inline int golomb_bs_get_ue(BitstreamContext *bc)
{
    unsigned int buf = bitstream_peek(bc, 32);

    if (buf >= (1 << 27)) {
        buf >>= 32 - 9;
        bitstream_skip_cache(bc, ff_golomb_vlc_len[buf]);

        return ff_ue_golomb_vlc_code[buf];
    } else {
        int log = 2 * av_log2(buf) - 31;

        bitstream_skip_cache(bc, 32 - log);
        if (log < 7)
            return AVERROR_INVALIDDATA;
        buf >>= log;
        buf--;

        return buf;
    }
}

/**
 * Read an unsigned Exp-Golomb code in the range 0 to UINT32_MAX-1.
 */
static inline unsigned golomb_bs_get_ue_long(BitstreamContext *bc)
{
    unsigned int buf = bitstream_peek(bc, 32);
    unsigned int log = 31 - av_log2(buf);
    bitstream_skip_cache(bc, log);
    return bitstream_read(bc, log + 1) - 1;
}

/**
 * read unsigned exp golomb code, constraint to a max of 31.
 * If the value encountered is not in 0..31, the return value
 * is outside the range 0..30.
 */
static inline int golomb_bs_get_ue_31(BitstreamContext *bc)
{
    unsigned int buf = bitstream_peek(bc, 32);

    buf >>= 32 - 9;
    bitstream_skip_cache(bc, ff_golomb_vlc_len[buf]);

    return ff_ue_golomb_vlc_code[buf];
}

static inline unsigned golomb_bs_get_ue_interleaved(BitstreamContext *bc)
{
    uint32_t buf = bitstream_peek(bc, 32);

    if (buf & 0xAA800000) {
        buf >>= 32 - 8;
        bitstream_skip_cache(bc, ff_interleaved_golomb_vlc_len[buf]);

        return ff_interleaved_ue_golomb_vlc_code[buf];
    } else {
        unsigned ret = 1;

        do {
            buf >>= 32 - 8;
            bitstream_skip_cache(bc, FFMIN(ff_interleaved_golomb_vlc_len[buf], 8));

            if (ff_interleaved_golomb_vlc_len[buf] != 9) {
                ret <<= (ff_interleaved_golomb_vlc_len[buf] - 1) >> 1;
                ret  |= ff_interleaved_dirac_golomb_vlc_code[buf];
                break;
            }
            ret = (ret << 4) | ff_interleaved_dirac_golomb_vlc_code[buf];
            buf = bitstream_peek(bc, 32);
        } while (bitstream_bits_left(bc) > 0);

        return ret - 1;
    }
}

/**
 * read unsigned truncated exp golomb code.
 */
static inline int golomb_bs_get_te0(BitstreamContext *bc, int range)
{
    av_assert2(range >= 1);

    if (range == 1)
        return 0;
    else if (range == 2)
        return bitstream_read(bc, 1) ^ 1;
    else
        return golomb_bs_get_ue(bc);
}

/**
 * read unsigned truncated exp golomb code.
 */
static inline int golomb_bs_get_te(BitstreamContext *bc, int range)
{
    av_assert2(range >= 1);

    if (range == 2)
        return bitstream_read(bc, 1) ^ 1;
    else
        return golomb_bs_get_ue(bc);
}

/**
 * read signed exp golomb code.
 */
static inline int golomb_bs_get_se(BitstreamContext *bc)
{
    unsigned int buf;

    buf = bitstream_peek(bc, 32);

    if (buf >= (1 << 27)) {
        buf >>= 32 - 9;
        bitstream_skip_cache(bc, ff_golomb_vlc_len[buf]);

        return ff_se_golomb_vlc_code[buf];
    } else {
        int log = 2 * av_log2(buf) - 31;
        buf >>= log;

        bitstream_skip_cache(bc, 32 - log);

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

        return buf;
    }
}

static inline int golomb_bs_get_se_long(BitstreamContext *bc)
{
    unsigned int buf = golomb_bs_get_ue_long(bc);
    int sign = (buf & 1) - 1;
    return ((buf >> 1) ^ sign) + 1;
}

static inline int golomb_bs_get_se_interleaved(BitstreamContext *bc)
{
    unsigned int buf;

    buf = bitstream_peek(bc, 32);

    if (buf & 0xAA800000) {
        buf >>= 32 - 8;
        bitstream_skip_cache(bc, ff_interleaved_golomb_vlc_len[buf]);

        return ff_interleaved_se_golomb_vlc_code[buf];
    } else {
        int log;
        bitstream_skip_cache(bc, 8);
        buf |= 1 | bitstream_peek(bc, 24);

        if ((buf & 0xAAAAAAAA) == 0)
            return INVALID_VLC;

        for (log = 31; (buf & 0x80000000) == 0; log--)
            buf = (buf << 2) - ((buf << log) >> (log - 1)) + (buf >> 30);

        bitstream_skip(bc, 63 - 2 * log - 8);

        return (signed) (((((buf << log) >> log) - 1) ^ -(buf & 0x1)) + 1) >> 1;
    }
}

static inline int golomb_bs_get_se_dirac(BitstreamContext *bc)
{
    uint32_t ret = golomb_bs_get_ue_interleaved(bc);

    if (ret) {
        int sign = -bitstream_read(bc, 1);
        ret = (ret ^ sign) - sign;
    }

    return ret;
}

/**
 * read unsigned golomb rice code (ffv1).
 */
static inline int golomb_bs_get_ur(BitstreamContext *bc, int k, int limit,
                                   int esc_len)
{
    unsigned int buf;
    int log;

    buf = bitstream_peek(bc, 32);

    log = av_log2(buf);

    if (log > 31 - limit) {
        buf >>= log - k;
        buf  += (30 - log) << k;
        bitstream_skip(bc, 32 + k - log);

        return buf;
    } else {
        bitstream_skip(bc, limit);
        buf = bitstream_read(bc, esc_len);

        return buf + limit - 1;
    }
}

/**
 * read unsigned golomb rice code (jpegls).
 */
static inline int golomb_bs_get_ur_jpegls(BitstreamContext *bc, int k, int limit,
                                          int esc_len)
{
    unsigned int buf;
    int log;

    buf = bitstream_peek(bc, 32);

    log = av_log2(buf);

    if (log - k >= 1 && 32 - log < limit) {
        buf >>= log - k;
        buf  += (30 - log) << k;
        bitstream_skip(bc, 32 + k - log);

        return buf;
    } else {
        int i;
        for (i = 0;
             i < limit && bitstream_peek(bc, 1) == 0 && bitstream_bits_left(bc) > 0;
             i++)
            bitstream_skip_cache(bc, 1);
        bitstream_skip(bc, 1);

        if (i < limit - 1) {
            buf = bitstream_read(bc, k);

            return buf + (i << k);
        } else if (i == limit - 1) {
            buf = bitstream_read(bc, esc_len);

            return buf + 1;
        } else
            return -1;
    }
}

/**
 * read signed golomb rice code (ffv1).
 */
static inline int golomb_bs_get_sr(BitstreamContext *bc, int k, int limit,
                                   int esc_len)
{
    unsigned v = golomb_bs_get_ur(bc, k, limit, esc_len);
    return (v >> 1) ^ -(v & 1);
}

/**
 * read signed golomb rice code (flac).
 */
static inline int golomb_bs_get_sr_flac(BitstreamContext *bc, int k, int limit,
                                        int esc_len)
{
    unsigned v = golomb_bs_get_ur_jpegls(bc, k, limit, esc_len);
    return (v >> 1) ^ -(v & 1);
}

/**
 * read unsigned golomb rice code (shorten).
 */
static inline unsigned int golomb_bs_get_ur_shorten(BitstreamContext *bc, int k)
{
    return golomb_bs_get_ur_jpegls(bc, k, INT_MAX, 0);
}

/**
 * read signed golomb rice code (shorten).
 */
static inline int golomb_bs_get_sr_shorten(BitstreamContext *bc, int k)
{
    int uvar = golomb_bs_get_ur_jpegls(bc, k + 1, INT_MAX, 0);
    return (uvar >> 1) ^ -(uvar & 1);
}

#endif /* AVCODEC_GOLOMB_BS_H */