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/*

 * copyright (c) 2004 Michael Niedermayer 

 *

 * 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

 * bitstream reader API header.

 */

#ifndef AVCODEC_GET_BITS_H

#define AVCODEC_GET_BITS_H

#include 

#include "libavutil/common.h"

#include "libavutil/intreadwrite.h"

#include "libavutil/log.h"

#include "libavutil/avassert.h"

#include "mathops.h"

/*

 * Safe bitstream reading:

 * optionally, the get_bits API can check to ensure that we

 * don't read past input buffer boundaries. This is protected

 * with CONFIG_SAFE_BITSTREAM_READER at the global level, and

 * then below that with UNCHECKED_BITSTREAM_READER at the per-

 * decoder level. This means that decoders that check internally

 * can "#define UNCHECKED_BITSTREAM_READER 1" to disable

 * overread checks.

 * Boundary checking causes a minor performance penalty so for

 * applications that won't want/need this, it can be disabled

 * globally using "#define CONFIG_SAFE_BITSTREAM_READER 0".

 */

#ifndef UNCHECKED_BITSTREAM_READER

#define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER

#endif

typedef struct GetBitContext {

    const uint8_t *buffer, *buffer_end;

    int index;

    int size_in_bits;

    int size_in_bits_plus8;

} GetBitContext;

#define VLC_TYPE int16_t

typedef struct VLC {

    int bits;

    VLC_TYPE (*table)[2]; ///< code, bits

    int table_size, table_allocated;

    void * volatile init_state;

} VLC;

typedef struct RL_VLC_ELEM {

    int16_t level;

    int8_t len;

    uint8_t run;

} RL_VLC_ELEM;

/* Bitstream reader API docs:

 * name

 *   arbitrary name which is used as prefix for the internal variables

 *

 * gb

 *   getbitcontext

 *

 * OPEN_READER(name, gb)

 *   load gb into local variables

 *

 * CLOSE_READER(name, gb)

 *   store local vars in gb

 *

 * UPDATE_CACHE(name, gb)

 *   Refill the internal cache from the bitstream.

 *   After this call at least MIN_CACHE_BITS will be available.

 *

 * GET_CACHE(name, gb)

 *   Will output the contents of the internal cache,

 *   next bit is MSB of 32 or 64 bit (FIXME 64bit).

 *

 * SHOW_UBITS(name, gb, num)

 *   Will return the next num bits.

 *

 * SHOW_SBITS(name, gb, num)

 *   Will return the next num bits and do sign extension.

 *

 * SKIP_BITS(name, gb, num)

 *   Will skip over the next num bits.

 *   Note, this is equivalent to SKIP_CACHE; SKIP_COUNTER.

 *

 * SKIP_CACHE(name, gb, num)

 *   Will remove the next num bits from the cache (note SKIP_COUNTER

 *   MUST be called before UPDATE_CACHE / CLOSE_READER).

 *

 * SKIP_COUNTER(name, gb, num)

 *   Will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS).

 *

 * LAST_SKIP_BITS(name, gb, num)

 *   Like SKIP_BITS, to be used if next call is UPDATE_CACHE or CLOSE_READER.

 *

 * For examples see get_bits, show_bits, skip_bits, get_vlc.

 */

#ifdef LONG_BITSTREAM_READER

#   define MIN_CACHE_BITS 32

#else

#   define MIN_CACHE_BITS 25

#endif

#if UNCHECKED_BITSTREAM_READER

#define OPEN_READER(name, gb)                   \

    unsigned int name ## _index = (gb)->index;  \

    unsigned int av_unused name ## _cache

#define HAVE_BITS_REMAINING(name, gb) 1

#else

#define OPEN_READER(name, gb)                   \

    unsigned int name ## _index = (gb)->index;  \

    unsigned int av_unused name ## _cache = 0;  \

    unsigned int av_unused name ## _size_plus8 = (gb)->size_in_bits_plus8

#define HAVE_BITS_REMAINING(name, gb) name ## _index < name ## _size_plus8

#endif

#define CLOSE_READER(name, gb) (gb)->index = name ## _index

# ifdef LONG_BITSTREAM_READER

# define UPDATE_CACHE_LE(name, gb) name ## _cache = \

      AV_RL64((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)

# define UPDATE_CACHE_BE(name, gb) name ## _cache = \

      AV_RB64((gb)->buffer + (name ## _index >> 3)) >> (32 - (name ## _index & 7))

#else

# define UPDATE_CACHE_LE(name, gb) name ## _cache = \

      AV_RL32((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)

# define UPDATE_CACHE_BE(name, gb) name ## _cache = \

      AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7)

#endif

#ifdef BITSTREAM_READER_LE

# define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb)

# define SKIP_CACHE(name, gb, num) name ## _cache >>= (num)

#else

# define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb)

# define SKIP_CACHE(name, gb, num) name ## _cache <<= (num)

#endif

#if UNCHECKED_BITSTREAM_READER

#   define SKIP_COUNTER(name, gb, num) name ## _index += (num)

#else

#   define SKIP_COUNTER(name, gb, num) \

    name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num))

#endif

#define SKIP_BITS(name, gb, num)                \

    do {                                        \

        SKIP_CACHE(name, gb, num);              \

        SKIP_COUNTER(name, gb, num);            \

    } while (0)

#define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)

#define SHOW_UBITS_LE(name, gb, num) zero_extend(name ## _cache, num)

#define SHOW_SBITS_LE(name, gb, num) sign_extend(name ## _cache, num)

#define SHOW_UBITS_BE(name, gb, num) NEG_USR32(name ## _cache, num)

#define SHOW_SBITS_BE(name, gb, num) NEG_SSR32(name ## _cache, num)

#ifdef BITSTREAM_READER_LE

#   define SHOW_UBITS(name, gb, num) SHOW_UBITS_LE(name, gb, num)

#   define SHOW_SBITS(name, gb, num) SHOW_SBITS_LE(name, gb, num)

#else

#   define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num)

#   define SHOW_SBITS(name, gb, num) SHOW_SBITS_BE(name, gb, num)

#endif

#define GET_CACHE(name, gb) ((uint32_t) name ## _cache)

static inline int get_bits_count(const GetBitContext *s)

{

    return s->index;

}

static inline void skip_bits_long(GetBitContext *s, int n)

{

#if UNCHECKED_BITSTREAM_READER

    s->index += n;

#else

    s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index);

#endif

}

/**

 * read mpeg1 dc style vlc (sign bit + mantisse with no MSB).

 * if MSB not set it is negative

 * @param n length in bits

 */

static inline int get_xbits(GetBitContext *s, int n)

{

    register int sign;

    register int32_t cache;

    OPEN_READER(re, s);

    av_assert2(n>0 && n<=25);

    UPDATE_CACHE(re, s);

    cache = GET_CACHE(re, s);

    sign  = ~cache >> 31;

    LAST_SKIP_BITS(re, s, n);

    CLOSE_READER(re, s);

    return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;

}

static inline int get_sbits(GetBitContext *s, int n)

{

    register int tmp;

    OPEN_READER(re, s);

    av_assert2(n>0 && n<=25);

    UPDATE_CACHE(re, s);

    tmp = SHOW_SBITS(re, s, n);

    LAST_SKIP_BITS(re, s, n);

    CLOSE_READER(re, s);

    return tmp;

}

/**

 * Read 1-25 bits.

 */

static inline unsigned int get_bits(GetBitContext *s, int n)

{

    register int tmp;

    OPEN_READER(re, s);

    av_assert2(n>0 && n<=25);

    UPDATE_CACHE(re, s);

    tmp = SHOW_UBITS(re, s, n);

    LAST_SKIP_BITS(re, s, n);

    CLOSE_READER(re, s);

    return tmp;

}

static inline unsigned int get_bits_le(GetBitContext *s, int n)

{

    register int tmp;

    OPEN_READER(re, s);

    av_assert2(n>0 && n<=25);

    UPDATE_CACHE_LE(re, s);

    tmp = SHOW_UBITS_LE(re, s, n);

    LAST_SKIP_BITS(re, s, n);

    CLOSE_READER(re, s);

    return tmp;

}

/**

 * Show 1-25 bits.

 */

static inline unsigned int show_bits(GetBitContext *s, int n)

{

    register int tmp;

    OPEN_READER(re, s);

    av_assert2(n>0 && n<=25);

    UPDATE_CACHE(re, s);

    tmp = SHOW_UBITS(re, s, n);

    return tmp;

}

static inline void skip_bits(GetBitContext *s, int n)

{

    OPEN_READER(re, s);

    LAST_SKIP_BITS(re, s, n);

    CLOSE_READER(re, s);

}

static inline unsigned int get_bits1(GetBitContext *s)

{

    unsigned int index = s->index;

    uint8_t result     = s->buffer[index >> 3];

#ifdef BITSTREAM_READER_LE

    result >>= index & 7;

    result  &= 1;

#else

    result <<= index & 7;

    result >>= 8 - 1;

#endif

#if !UNCHECKED_BITSTREAM_READER

    if (s->index < s->size_in_bits_plus8)

#endif

        index++;

    s->index = index;

    return result;

}

static inline unsigned int show_bits1(GetBitContext *s)

{

    return show_bits(s, 1);

}

static inline void skip_bits1(GetBitContext *s)

{

    skip_bits(s, 1);

}

/**

 * Read 0-32 bits.

 */

static inline unsigned int get_bits_long(GetBitContext *s, int n)

{

    if (!n) {

        return 0;

    } else if (n <= MIN_CACHE_BITS) {

        return get_bits(s, n);

    } else {

#ifdef BITSTREAM_READER_LE

        unsigned ret = get_bits(s, 16);

        return ret | (get_bits(s, n - 16) << 16);

#else

        unsigned ret = get_bits(s, 16) << (n - 16);

        return ret | get_bits(s, n - 16);

#endif

    }

}

/**

 * Read 0-64 bits.

 */

static inline uint64_t get_bits64(GetBitContext *s, int n)

{

    if (n <= 32) {

        return get_bits_long(s, n);

    } else {

#ifdef BITSTREAM_READER_LE

        uint64_t ret = get_bits_long(s, 32);

        return ret | (uint64_t) get_bits_long(s, n - 32) << 32;

#else

        uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32;

        return ret | get_bits_long(s, 32);

#endif

    }

}

/**

 * Read 0-32 bits as a signed integer.

 */

static inline int get_sbits_long(GetBitContext *s, int n)

{

    return sign_extend(get_bits_long(s, n), n);

}

/**

 * Show 0-32 bits.

 */

static inline unsigned int show_bits_long(GetBitContext *s, int n)

{

    if (n <= MIN_CACHE_BITS) {

        return show_bits(s, n);

    } else {

        GetBitContext gb = *s;

        return get_bits_long(&gb, n);

    }

}

static inline int check_marker(GetBitContext *s, const char *msg)

{

    int bit = get_bits1(s);

    if (!bit)

        av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg);

    return bit;

}

/**

 * Initialize GetBitContext.

 * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes

 *        larger than the actual read bits because some optimized bitstream

 *        readers read 32 or 64 bit at once and could read over the end

 * @param bit_size the size of the buffer in bits

 * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.

 */

static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer,

                                int bit_size)

{

    int buffer_size;

    int ret = 0;

    if (bit_size >= INT_MAX - 7 || bit_size < 0 || !buffer) {

        buffer_size = bit_size = 0;

        buffer      = NULL;

        ret         = AVERROR_INVALIDDATA;

    }

    buffer_size = (bit_size + 7) >> 3;

    s->buffer             = buffer;

    s->size_in_bits       = bit_size;

    s->size_in_bits_plus8 = bit_size + 8;

    s->buffer_end         = buffer + buffer_size;

    s->index              = 0;

    return ret;

}

/**

 * Initialize GetBitContext.

 * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes

 *        larger than the actual read bits because some optimized bitstream

 *        readers read 32 or 64 bit at once and could read over the end

 * @param byte_size the size of the buffer in bytes

 * @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.

 */

static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer,

                                 int byte_size)

{

    if (byte_size > INT_MAX / 8 || byte_size < 0)

        byte_size = -1;

    return init_get_bits(s, buffer, byte_size * 8);

}

static inline const uint8_t *align_get_bits(GetBitContext *s)

{

    int n = -get_bits_count(s) & 7;

    if (n)

        skip_bits(s, n);

    return s->buffer + (s->index >> 3);

}

#define init_vlc(vlc, nb_bits, nb_codes,                \

                 bits, bits_wrap, bits_size,            \

                 codes, codes_wrap, codes_size,         \

                 flags)                                 \

    ff_init_vlc_sparse(vlc, nb_bits, nb_codes,          \

                       bits, bits_wrap, bits_size,      \

                       codes, codes_wrap, codes_size,   \

                       NULL, 0, 0, flags)

int ff_init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,

                       const void *bits, int bits_wrap, int bits_size,

                       const void *codes, int codes_wrap, int codes_size,

                       const void *symbols, int symbols_wrap, int symbols_size,

                       int flags);

void ff_free_vlc(VLC *vlc);

#define INIT_VLC_LE             2

#define INIT_VLC_USE_NEW_STATIC 4

#define INIT_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, static_size)       \

    do {                                                                   \

        static VLC_TYPE table[static_size][2];                             \

        (vlc)->table           = table;                                    \

        (vlc)->table_allocated = static_size;                              \

        init_vlc(vlc, bits, a, b, c, d, e, f, g, INIT_VLC_USE_NEW_STATIC); \

    } while (0)

/**

 * If the vlc code is invalid and max_depth=1, then no bits will be removed.

 * If the vlc code is invalid and max_depth>1, then the number of bits removed

 * is undefined.

 */

#define GET_VLC(code, name, gb, table, bits, max_depth)         \

    do {                                                        \

        int n, nb_bits;                                         \

        unsigned int index;                                     \

                                                                \

        index = SHOW_UBITS(name, gb, bits);                     \

        code  = table[index][0];                                \

        n     = table[index][1];                                \

                                                                \

        if (max_depth > 1 && n < 0) {                           \

            LAST_SKIP_BITS(name, gb, bits);                     \

            UPDATE_CACHE(name, gb);                             \

                                                                \

            nb_bits = -n;                                       \

                                                                \

            index = SHOW_UBITS(name, gb, nb_bits) + code;       \

            code  = table[index][0];                            \

            n     = table[index][1];                            \

            if (max_depth > 2 && n < 0) {                       \

                LAST_SKIP_BITS(name, gb, nb_bits);              \

                UPDATE_CACHE(name, gb);                         \

                                                                \

                nb_bits = -n;                                   \

                                                                \

                index = SHOW_UBITS(name, gb, nb_bits) + code;   \

                code  = table[index][0];                        \

                n     = table[index][1];                        \

            }                                                   \

        }                                                       \

        SKIP_BITS(name, gb, n);                                 \

    } while (0)

#define GET_RL_VLC(level, run, name, gb, table, bits,           \

                   max_depth, need_update)                      \

    do {                                                        \

        int n, nb_bits;                                         \

        unsigned int index;                                     \

                                                                \

        index = SHOW_UBITS(name, gb, bits);                     \

        level = table[index].level;                             \

        n     = table[index].len;                               \

                                                                \

        if (max_depth > 1 && n < 0) {                           \

            SKIP_BITS(name, gb, bits);                          \

            if (need_update) {                                  \

                UPDATE_CACHE(name, gb);                         \

            }                                                   \

                                                                \

            nb_bits = -n;                                       \

                                                                \

            index = SHOW_UBITS(name, gb, nb_bits) + level;      \

            level = table[index].level;                         \

            n     = table[index].len;                           \

        }                                                       \

        run = table[index].run;                                 \

        SKIP_BITS(name, gb, n);                                 \

    } while (0)

/**

 * Parse a vlc code.

 * @param bits is the number of bits which will be read at once, must be

 *             identical to nb_bits in init_vlc()

 * @param max_depth is the number of times bits bits must be read to completely

 *                  read the longest vlc code

 *                  = (max_vlc_length + bits - 1) / bits

 */

static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],

                                     int bits, int max_depth)

{

    int code;

    OPEN_READER(re, s);

    UPDATE_CACHE(re, s);

    GET_VLC(code, re, s, table, bits, max_depth);

    CLOSE_READER(re, s);

    return code;

}

static inline int decode012(GetBitContext *gb)

{

    int n;

    n = get_bits1(gb);

    if (n == 0)

        return 0;

    else

        return get_bits1(gb) + 1;

}

static inline int decode210(GetBitContext *gb)

{

    if (get_bits1(gb))

        return 0;

    else

        return 2 - get_bits1(gb);

}

static inline int get_bits_left(GetBitContext *gb)

{

    return gb->size_in_bits - get_bits_count(gb);

}

//#define TRACE

#ifdef TRACE

static inline void print_bin(int bits, int n)

{

    int i;

    for (i = n - 1; i >= 0; i--)

        av_log(NULL, AV_LOG_DEBUG, "%d", (bits >> i) & 1);

    for (i = n; i < 24; i++)

        av_log(NULL, AV_LOG_DEBUG, " ");

}

static inline int get_bits_trace(GetBitContext *s, int n, const char *file,

                                 const char *func, int line)

{

    int r = get_bits(s, n);

    print_bin(r, n);

    av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d bit @%5d in %s %s:%d\n",

           r, n, r, get_bits_count(s) - n, file, func, line);

    return r;

}

static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2],

                                int bits, int max_depth, const char *file,

                                const char *func, int line)

{

    int show  = show_bits(s, 24);

    int pos   = get_bits_count(s);

    int r     = get_vlc2(s, table, bits, max_depth);

    int len   = get_bits_count(s) - pos;

    int bits2 = show >> (24 - len);

    print_bin(bits2, len);

    av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d vlc @%5d in %s %s:%d\n",

           bits2, len, r, pos, file, func, line);

    return r;

}

static inline int get_xbits_trace(GetBitContext *s, int n, const char *file,

                                  const char *func, int line)

{

    int show = show_bits(s, n);

    int r    = get_xbits(s, n);

    print_bin(show, n);

    av_log(NULL, AV_LOG_DEBUG, "%5d %2d %3d xbt @%5d in %s %s:%d\n",

           show, n, r, get_bits_count(s) - n, file, func, line);

    return r;

}

#define get_bits(s, n)  get_bits_trace(s , n, __FILE__, __PRETTY_FUNCTION__, __LINE__)

#define get_bits1(s)    get_bits_trace(s,  1, __FILE__, __PRETTY_FUNCTION__, __LINE__)

#define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)

#define get_vlc(s, vlc)             get_vlc_trace(s, (vlc)->table, (vlc)->bits,   3, __FILE__, __PRETTY_FUNCTION__, __LINE__)

#define get_vlc2(s, tab, bits, max) get_vlc_trace(s,          tab,        bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__)

#define tprintf(p, ...) av_log(p, AV_LOG_DEBUG, __VA_ARGS__)

#else //TRACE

#define tprintf(p, ...) { }

#endif

#endif /* AVCODEC_GET_BITS_H */