/*
  * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
  *

  * 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/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 */