libavcodec/get_bits.h - third_party/ffmpeg - Git at Google

 /*
  * 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 "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;
 } 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;    \
     av_unused unsigned int 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 BITSTREAM_READER_LE

 # ifdef LONG_BITSTREAM_READER
 #   define UPDATE_CACHE(name, gb) name##_cache = \
         AV_RL64((gb)->buffer + (name##_index >> 3)) >> (name##_index & 7)
 # else
 #   define UPDATE_CACHE(name, gb) name##_cache = \
         AV_RL32((gb)->buffer + (name##_index >> 3)) >> (name##_index & 7)
 # endif

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

 #else

 # ifdef LONG_BITSTREAM_READER
 #   define UPDATE_CACHE(name, gb) name##_cache = \
         AV_RB64((gb)->buffer + (name##_index >> 3)) >> (32 - (name##_index & 7))
 # else
 #   define UPDATE_CACHE(name, gb) name##_cache = \
         AV_RB32((gb)->buffer + (name##_index >> 3)) << (name##_index & 7)
 # endif

 # 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)

 #ifdef BITSTREAM_READER_LE
 #   define SHOW_UBITS(name, gb, num) zero_extend(name##_cache, num)
 #   define SHOW_SBITS(name, gb, num) sign_extend(name##_cache, num)
 #else
 #   define SHOW_UBITS(name, gb, num) NEG_USR32(name##_cache, num)
 #   define SHOW_SBITS(name, gb, num) NEG_SSR32(name##_cache, 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);
     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);
     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);
     UPDATE_CACHE(re, s);
     tmp = SHOW_UBITS(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);
     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);
     UPDATE_CACHE(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 <= MIN_CACHE_BITS)
         return get_bits(s, n);
     else {
 #ifdef BITSTREAM_READER_LE
         int ret = get_bits(s, 16);
         return ret | (get_bits(s, n-16) << 16);
 #else
         int ret = get_bits(s, 16) << (n-16);
         return ret | get_bits(s, n-16);
 #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_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;
 }

 static inline void align_get_bits(GetBitContext *s)
 {
     int n = -get_bits_count(s) & 7;
     if (n) skip_bits(s, n);
 }

 #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);
 #define INIT_VLC_LE         2
 #define INIT_VLC_USE_NEW_STATIC 4
 void ff_free_vlc(VLC *vlc);

 #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, 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, 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, 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 */
	/*
	* 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 "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;
	} 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; \
	av_unused unsigned int 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 BITSTREAM_READER_LE

	# ifdef LONG_BITSTREAM_READER
	# define UPDATE_CACHE(name, gb) name##_cache = \
	AV_RL64((gb)->buffer + (name##_index >> 3)) >> (name##_index & 7)
	# else
	# define UPDATE_CACHE(name, gb) name##_cache = \
	AV_RL32((gb)->buffer + (name##_index >> 3)) >> (name##_index & 7)
	# endif

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

	#else

	# ifdef LONG_BITSTREAM_READER
	# define UPDATE_CACHE(name, gb) name##_cache = \
	AV_RB64((gb)->buffer + (name##_index >> 3)) >> (32 - (name##_index & 7))
	# else
	# define UPDATE_CACHE(name, gb) name##_cache = \
	AV_RB32((gb)->buffer + (name##_index >> 3)) << (name##_index & 7)
	# endif

	# 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)

	#ifdef BITSTREAM_READER_LE
	# define SHOW_UBITS(name, gb, num) zero_extend(name##_cache, num)
	# define SHOW_SBITS(name, gb, num) sign_extend(name##_cache, num)
	#else
	# define SHOW_UBITS(name, gb, num) NEG_USR32(name##_cache, num)
	# define SHOW_SBITS(name, gb, num) NEG_SSR32(name##_cache, 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);
	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);
	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);
	UPDATE_CACHE(re, s);
	tmp = SHOW_UBITS(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);
	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);
	UPDATE_CACHE(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 <= MIN_CACHE_BITS)
	return get_bits(s, n);
	else {
	#ifdef BITSTREAM_READER_LE
	int ret = get_bits(s, 16);
	return ret \| (get_bits(s, n-16) << 16);
	#else
	int ret = get_bits(s, 16) << (n-16);
	return ret \| get_bits(s, n-16);
	#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_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;
	}

	static inline void align_get_bits(GetBitContext *s)
	{
	int n = -get_bits_count(s) & 7;
	if (n) skip_bits(s, n);
	}

	#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);
	#define INIT_VLC_LE 2
	#define INIT_VLC_USE_NEW_STATIC 4
	void ff_free_vlc(VLC *vlc);

	#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, 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, 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, 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 */