/*
 * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
 * Copyright (c) 2016 Alexandra Hájková
 *
 * 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 <stdint.h>

#include <libavutil/avassert.h>
#include <libavutil/common.h>
#include <libavutil/intreadwrite.h>
#include <libavutil/log.h>

#include "defs.h"
#include "mathops.h"
#include "vlc.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 0
#endif

#ifndef CACHED_BITSTREAM_READER
#define CACHED_BITSTREAM_READER 0
#endif

#include "cbs/h2645_parse.h"

static inline unsigned int get_bits(GetBitContext *s, int n);
static inline void skip_bits(GetBitContext *s, int n);
static inline unsigned int show_bits(GetBitContext *s, int n);

/* 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 bits (FIXME 64 bits).
 *
 * 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.
 *
 * BITS_LEFT(name, gb)
 *   Return the number of bits left
 *
 * For examples see get_bits, show_bits, skip_bits, get_vlc.
 */

#if CACHED_BITSTREAM_READER
#define MIN_CACHE_BITS 64
#elif defined LONG_BITSTREAM_READER
#define MIN_CACHE_BITS 32
#else
#define MIN_CACHE_BITS 25
#endif

#if !CACHED_BITSTREAM_READER

#define OPEN_READER_NOSIZE(name, gb)       \
  unsigned int name##_index = (gb)->index; \
  unsigned int av_unused name##_cache

#if UNCHECKED_BITSTREAM_READER
#define OPEN_READER(name, gb) OPEN_READER_NOSIZE(name, gb)

#define BITS_AVAILABLE(name, gb) 1
#else
#define OPEN_READER(name, gb)   \
  OPEN_READER_NOSIZE(name, gb); \
  unsigned int name##_size_plus8 = (gb)->size_in_bits_plus8

#define BITS_AVAILABLE(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 BITS_LEFT(name, gb) ((int)((gb)->size_in_bits - name##_index))

#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)

#endif

static inline int get_bits_count(const GetBitContext *s) {
#if CACHED_BITSTREAM_READER
  return s->index - s->bits_left;
#else
  return s->index;
#endif
}

#if CACHED_BITSTREAM_READER
static inline void refill_32(GetBitContext *s, int is_le) {
#if !UNCHECKED_BITSTREAM_READER
  if(s->index >> 3 >= s->buffer_end - s->buffer)
    return;
#endif

  if(is_le)
    s->cache = (uint64_t)AV_RL32(s->buffer + (s->index >> 3)) << s->bits_left | s->cache;
  else
    s->cache = s->cache | (uint64_t)AV_RB32(s->buffer + (s->index >> 3)) << (32 - s->bits_left);
  s->index += 32;
  s->bits_left += 32;
}

static inline void refill_64(GetBitContext *s, int is_le) {
#if !UNCHECKED_BITSTREAM_READER
  if(s->index >> 3 >= s->buffer_end - s->buffer)
    return;
#endif

  if(is_le)
    s->cache = AV_RL64(s->buffer + (s->index >> 3));
  else
    s->cache = AV_RB64(s->buffer + (s->index >> 3));
  s->index += 64;
  s->bits_left = 64;
}

static inline uint64_t get_val(GetBitContext *s, unsigned n, int is_le) {
  uint64_t ret;
  av_assert2(n > 0 && n <= 63);
  if(is_le) {
    ret = s->cache & ((UINT64_C(1) << n) - 1);
    s->cache >>= n;
  }
  else {
    ret = s->cache >> (64 - n);
    s->cache <<= n;
  }
  s->bits_left -= n;
  return ret;
}

static inline unsigned show_val(const GetBitContext *s, unsigned n) {
#ifdef BITSTREAM_READER_LE
  return s->cache & ((UINT64_C(1) << n) - 1);
#else
  return s->cache >> (64 - n);
#endif
}
#endif

/**
 * Skips the specified number of bits.
 * @param n the number of bits to skip,
 *          For the UNCHECKED_BITSTREAM_READER this must not cause the distance
 *          from the start to overflow int32_t. Staying within the bitstream + padding
 *          is sufficient, too.
 */
static inline void skip_bits_long(GetBitContext *s, int n) {
#if CACHED_BITSTREAM_READER
  skip_bits(s, n);
#else
#if UNCHECKED_BITSTREAM_READER
  s->index += n;
#else
  s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index);
#endif
#endif
}

#if CACHED_BITSTREAM_READER
static inline void skip_remaining(GetBitContext *s, unsigned n) {
#ifdef BITSTREAM_READER_LE
  s->cache >>= n;
#else
  s->cache <<= n;
#endif
  s->bits_left -= n;
}
#endif

/**
 * Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB).
 * if MSB not set it is negative
 * @param n length in bits
 */
static inline int get_xbits(GetBitContext *s, int n) {
#if CACHED_BITSTREAM_READER
  int32_t cache = show_bits(s, 32);
  int sign      = ~cache >> 31;
  skip_remaining(s, n);

  return ((((uint32_t)(sign ^ cache)) >> (32 - n)) ^ sign) - sign;
#else
  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;
#endif
}

#if !CACHED_BITSTREAM_READER
static inline int get_xbits_le(GetBitContext *s, int n) {
  register int sign;
  register int32_t cache;
  OPEN_READER(re, s);
  av_assert2(n > 0 && n <= 25);
  UPDATE_CACHE_LE(re, s);
  cache = GET_CACHE(re, s);
  sign  = sign_extend(~cache, n) >> 31;
  LAST_SKIP_BITS(re, s, n);
  CLOSE_READER(re, s);
  return (zero_extend(sign ^ cache, n) ^ sign) - sign;
}
#endif

static inline int get_sbits(GetBitContext *s, int n) {
  register int tmp;
#if CACHED_BITSTREAM_READER
  av_assert2(n > 0 && n <= 25);
  tmp = sign_extend(get_bits(s, n), n);
#else
  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);
#endif
  return tmp;
}

/**
 * Read 1-25 bits.
 */
static inline unsigned int get_bits(GetBitContext *s, int n) {
  register unsigned int tmp;
#if CACHED_BITSTREAM_READER

  av_assert2(n > 0 && n <= 32);
  if(n > s->bits_left) {
#ifdef BITSTREAM_READER_LE
    refill_32(s, 1);
#else
    refill_32(s, 0);
#endif
    if(s->bits_left < 32)
      s->bits_left = n;
  }

#ifdef BITSTREAM_READER_LE
  tmp = get_val(s, n, 1);
#else
  tmp = get_val(s, n, 0);
#endif
#else
  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);
#endif
  av_assert2(tmp < UINT64_C(1) << n);
  return tmp;
}

/**
 * Read 0-25 bits.
 */
static av_always_inline int get_bitsz(GetBitContext *s, int n) {
  return n ? get_bits(s, n) : 0;
}

static inline unsigned int get_bits_le(GetBitContext *s, int n) {
#if CACHED_BITSTREAM_READER
  av_assert2(n > 0 && n <= 32);
  if(n > s->bits_left) {
    refill_32(s, 1);
    if(s->bits_left < 32)
      s->bits_left = n;
  }

  return get_val(s, n, 1);
#else
  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;
#endif
}

/**
 * Show 1-25 bits.
 */
static inline unsigned int show_bits(GetBitContext *s, int n) {
  register unsigned int tmp;
#if CACHED_BITSTREAM_READER
  if(n > s->bits_left)
#ifdef BITSTREAM_READER_LE
    refill_32(s, 1);
#else
    refill_32(s, 0);
#endif

  tmp = show_val(s, n);
#else
  OPEN_READER_NOSIZE(re, s);
  av_assert2(n > 0 && n <= 25);
  UPDATE_CACHE(re, s);
  tmp = SHOW_UBITS(re, s, n);
#endif
  return tmp;
}

static inline void skip_bits(GetBitContext *s, int n) {
#if CACHED_BITSTREAM_READER
  if(n < s->bits_left)
    skip_remaining(s, n);
  else {
    n -= s->bits_left;
    s->cache     = 0;
    s->bits_left = 0;

    if(n >= 64) {
      unsigned skip = (n / 8) * 8;

      n -= skip;
      s->index += skip;
    }
#ifdef BITSTREAM_READER_LE
    refill_64(s, 1);
#else
    refill_64(s, 0);
#endif
    if(n)
      skip_remaining(s, n);
  }
#else
  OPEN_READER(re, s);
  LAST_SKIP_BITS(re, s, n);
  CLOSE_READER(re, s);
#endif
}

static inline unsigned int get_bits1(GetBitContext *s) {
#if CACHED_BITSTREAM_READER
  if(!s->bits_left)
#ifdef BITSTREAM_READER_LE
    refill_64(s, 1);
#else
    refill_64(s, 0);
#endif

#ifdef BITSTREAM_READER_LE
  return get_val(s, 1, 1);
#else
  return get_val(s, 1, 0);
#endif
#else
  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;
#endif
}

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) {
  av_assert2(n >= 0 && n <= 32);
  if(!n) {
    return 0;
#if CACHED_BITSTREAM_READER
  }
  return get_bits(s, n);
#else
  }
  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
  }
#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) {
  // sign_extend(x, 0) is undefined
  if(!n)
    return 0;

  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(void *logctx, GetBitContext *s, const char *msg) {
  int bit = get_bits1(s);
  if(!bit)
    av_log(logctx, AV_LOG_INFO, "Marker bit missing at %d of %d %s\n",
      get_bits_count(s) - 1, s->size_in_bits, msg);

  return bit;
}

static inline int init_get_bits_xe(GetBitContext *s, const uint8_t *buffer,
  int bit_size, int is_le) {
  int buffer_size;
  int ret = 0;

  if(bit_size >= INT_MAX - FFMAX(7, AV_INPUT_BUFFER_PADDING_SIZE * 8) || bit_size < 0 || !buffer) {
    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;

#if CACHED_BITSTREAM_READER
  s->cache     = 0;
  s->bits_left = 0;
  refill_64(s, is_le);
#endif

  return ret;
}

/**
 * Initialize GetBitContext.
 * @param buffer bitstream buffer, must be AV_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) {
#ifdef BITSTREAM_READER_LE
  return init_get_bits_xe(s, buffer, bit_size, 1);
#else
  return init_get_bits_xe(s, buffer, bit_size, 0);
#endif
}

/**
 * Initialize GetBitContext.
 * @param buffer bitstream buffer, must be AV_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 int init_get_bits8_le(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_xe(s, buffer, byte_size * 8, 1);
}

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);
}

/**
 * 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;                        \
      if(max_depth > 2 && n < 0) {                     \
        LAST_SKIP_BITS(name, gb, nb_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)

/* Return the LUT element for the given bitstream configuration. */
static inline int set_idx(GetBitContext *s, int code, int *n, int *nb_bits,
  VLC_TYPE (*table)[2]) {
  unsigned idx;

  *nb_bits = -*n;
  idx      = show_bits(s, *nb_bits) + code;
  *n       = table[idx][1];

  return table[idx][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
 * @returns the code parsed or -1 if no vlc matches
 */
static av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
  int bits, int max_depth) {
#if CACHED_BITSTREAM_READER
  int nb_bits;
  unsigned idx = show_bits(s, bits);
  int code     = table[idx][0];
  int n        = table[idx][1];

  if(max_depth > 1 && n < 0) {
    skip_remaining(s, bits);
    code = set_idx(s, code, &n, &nb_bits, table);
    if(max_depth > 2 && n < 0) {
      skip_remaining(s, nb_bits);
      code = set_idx(s, code, &n, &nb_bits, table);
    }
  }
  skip_remaining(s, n);

  return code;
#else
  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;
#endif
}

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);
}

static inline int skip_1stop_8data_bits(GetBitContext *gb) {
  if(get_bits_left(gb) <= 0)
    return AVERROR_INVALIDDATA;

  while(get_bits1(gb)) {
    skip_bits(gb, 8);
    if(get_bits_left(gb) <= 0)
      return AVERROR_INVALIDDATA;
  }

  return 0;
}

#endif /* AVCODEC_GET_BITS_H */