drivers/amvdec_ports/utils/get_bits.h - manifest_repos/media_modules - Git at Google

 #ifndef AVCODEC_GET_BITS_H
 #define AVCODEC_GET_BITS_H

 #include <linux/kernel.h>
 #include <linux/types.h>
 #include "common.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".
  */

 struct get_bits_context {
 	const u8 *buffer;
 	const u8 *buffer_end;
 	int index;
 	int size_in_bits;
 	int size_in_bits_plus8;
 };

 /* Bitstream reader API docs:
  * name
  *   arbitrary name which is used as prefix for the internal variables
  *
  * gb
  *   struct get_bits_context
  *
  * 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.
  */

 #define OPEN_READER_NOSIZE(name, gb)		\
 	u32 name ## _index = (gb)->index;	\
 	u32 name ## _cache

 #define OPEN_READER(name, gb) OPEN_READER_NOSIZE(name, gb)
 #define BITS_AVAILABLE(name, gb) 1

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

 #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)

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

 #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 GET_CACHE(name, gb) ((u32) name ## _cache)

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

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

 #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

 static inline const int sign_extend(int val, u32 bits)
 {
 	u32 shift = 8 * sizeof(int) - bits;

 	union { u32 u; int s; } v = { (u32) val << shift };
 	return v.s >> shift;
 }

 static inline u32 zero_extend(u32 val, u32 bits)
 {
 	return (val << ((8 * sizeof(int)) - bits)) >> ((8 * sizeof(int)) - bits);
 }

 static inline int get_bits_count(const struct get_bits_context *s)
 {
 	return s->index;
 }

 /**
  * 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 int. Staying within the bitstream + padding
  *          is sufficient, too.
  */
 static inline void skip_bits_long(struct get_bits_context *s, int n)
 {
 	s->index += n;
 }

 /**
  * 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(struct get_bits_context *s, int n)
 {
 	register int sign;
 	register int 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_xbits_le(struct get_bits_context *s, int n)
 {
 	register int sign;
 	register int cache;

 	OPEN_READER(re, s);
 	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;
 }

 static inline int get_sbits(struct get_bits_context *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 u32 get_bits(struct get_bits_context *s, int n)
 {
 	register u32 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;
 }

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

 static inline u32 get_bits_le(struct get_bits_context *s, int n)
 {
 	register int tmp;

 	OPEN_READER(re, s);
 	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 u32 show_bits(struct get_bits_context *s, int n)
 {
 	register u32 tmp;

 	OPEN_READER_NOSIZE(re, s);
 	UPDATE_CACHE(re, s);
 	tmp = SHOW_UBITS(re, s, n);

 	return tmp;
 }

 static inline void skip_bits(struct get_bits_context *s, int n)
 {
 	u32 re_index = s->index;
 	LAST_SKIP_BITS(re, s, n);
 	CLOSE_READER(re, s);
 }

 static inline u32 get_bits1(struct get_bits_context *s)
 {
 	u32 index = s->index;
 	u8 result = s->buffer[index >> 3];

 #ifdef BITSTREAM_READER_LE
 	result >>= index & 7;
 	result  &= 1;
 #else
 	result <<= index & 7;
 	result >>= 8 - 1;
 #endif

 	index++;
 	s->index = index;

 	return result;
 }

 static inline u32 show_bits1(struct get_bits_context *s)
 {
 	return show_bits(s, 1);
 }

 static inline void skip_bits1(struct get_bits_context *s)
 {
 	skip_bits(s, 1);
 }

 /**
  * Read 0-32 bits.
  */
 static inline u32 get_bits_long(struct get_bits_context *s, int n)
 {
 	if (!n) {
 		return 0;
 	} else if (n <= MIN_CACHE_BITS) {
 		return get_bits(s, n);
 	} else {
 #ifdef BITSTREAM_READER_LE
 		u32 ret = get_bits(s, 16);
 		return ret | (get_bits(s, n - 16) << 16);
 #else
 		u32 ret = get_bits(s, 16) << (n - 16);
 		return ret | get_bits(s, n - 16);
 #endif
 	}
 }

 /**
  * Read 0-64 bits.
  */
 static inline u64 get_bits64(struct get_bits_context *s, int n)
 {
 	if (n <= 32) {
 		return get_bits_long(s, n);
 	} else {
 #ifdef BITSTREAM_READER_LE
 		u64 ret = get_bits_long(s, 32);
 		return ret | (u64) get_bits_long(s, n - 32) << 32;
 #else
 		u64 ret = (u64) 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(struct get_bits_context *s, int n)
 {
 	if (!n)
 		return 0;

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

 /**
  * Show 0-32 bits.
  */
 static inline u32 show_bits_long(struct get_bits_context *s, int n)
 {
 	if (n <= MIN_CACHE_BITS) {
 		return show_bits(s, n);
 	} else {
 		struct get_bits_context gb = *s;

 		return get_bits_long(&gb, n);
 	}
 }

 static inline int check_marker(struct get_bits_context *s, const char *msg)
 {
 	int bit = get_bits1(s);

 	if (!bit)
 		pr_err("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(struct get_bits_context *s,
 	const u8 *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         = -1;
 	}

 	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 struct get_bits_context.
  * @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, -1 if the buffer_size would overflow.
  */
 static inline int init_get_bits(struct get_bits_context *s,
 	const u8 *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 struct get_bits_context.
  * @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, -1 if the buffer_size would overflow.
  */
 static inline int init_get_bits8(struct get_bits_context *s,
 	const u8 *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(struct get_bits_context *s,
 	const u8 *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 u8 *align_get_bits(struct get_bits_context *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;                                         \
         u32 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;                                         \
         u32 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(struct get_bits_context *s,
 	int code, int *n, int *nb_bits, int (*table)[2])
 {
 	u32 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 inline int get_vlc2(struct get_bits_context *s,
 	int (*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(struct get_bits_context *gb)
 {
 	int n;

 	n = get_bits1(gb);
 	if (n == 0)
 		return 0;
 	else
 		return get_bits1(gb) + 1;
 }

 static inline int decode210(struct get_bits_context *gb)
 {
 	if (get_bits1(gb))
 		return 0;
 	else
 		return 2 - get_bits1(gb);
 }

 static inline int get_bits_left(struct get_bits_context *gb)
 {
 	return gb->size_in_bits - get_bits_count(gb);
 }

 static inline int skip_1stop_8data_bits(struct get_bits_context *gb)
 {
 	if (get_bits_left(gb) <= 0)
 	return -1;

 	while (get_bits1(gb)) {
 		skip_bits(gb, 8);
 		if (get_bits_left(gb) <= 0)
 			return -1;
 	}

 	return 0;
 }

 #endif /* AVCODEC_GET_BITS_H */
	#ifndef AVCODEC_GET_BITS_H
	#define AVCODEC_GET_BITS_H

	#include <linux/kernel.h>
	#include <linux/types.h>
	#include "common.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".
	*/

	struct get_bits_context {
	const u8 *buffer;
	const u8 *buffer_end;
	int index;
	int size_in_bits;
	int size_in_bits_plus8;
	};

	/* Bitstream reader API docs:
	* name
	* arbitrary name which is used as prefix for the internal variables
	*
	* gb
	* struct get_bits_context
	*
	* 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.
	*/

	#define OPEN_READER_NOSIZE(name, gb) \
	u32 name ## _index = (gb)->index; \
	u32 name ## _cache

	#define OPEN_READER(name, gb) OPEN_READER_NOSIZE(name, gb)
	#define BITS_AVAILABLE(name, gb) 1

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

	#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)

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

	#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 GET_CACHE(name, gb) ((u32) name ## _cache)

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

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

	#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

	static inline const int sign_extend(int val, u32 bits)
	{
	u32 shift = 8 * sizeof(int) - bits;

	union { u32 u; int s; } v = { (u32) val << shift };
	return v.s >> shift;
	}

	static inline u32 zero_extend(u32 val, u32 bits)
	{
	return (val << ((8 * sizeof(int)) - bits)) >> ((8 * sizeof(int)) - bits);
	}

	static inline int get_bits_count(const struct get_bits_context *s)
	{
	return s->index;
	}

	/**
	* 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 int. Staying within the bitstream + padding
	* is sufficient, too.
	*/
	static inline void skip_bits_long(struct get_bits_context *s, int n)
	{
	s->index += n;
	}

	/**
	* 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(struct get_bits_context *s, int n)
	{
	register int sign;
	register int 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_xbits_le(struct get_bits_context *s, int n)
	{
	register int sign;
	register int cache;

	OPEN_READER(re, s);
	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;
	}

	static inline int get_sbits(struct get_bits_context *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 u32 get_bits(struct get_bits_context *s, int n)
	{
	register u32 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;
	}

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

	static inline u32 get_bits_le(struct get_bits_context *s, int n)
	{
	register int tmp;

	OPEN_READER(re, s);
	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 u32 show_bits(struct get_bits_context *s, int n)
	{
	register u32 tmp;

	OPEN_READER_NOSIZE(re, s);
	UPDATE_CACHE(re, s);
	tmp = SHOW_UBITS(re, s, n);

	return tmp;
	}

	static inline void skip_bits(struct get_bits_context *s, int n)
	{
	u32 re_index = s->index;
	LAST_SKIP_BITS(re, s, n);
	CLOSE_READER(re, s);
	}

	static inline u32 get_bits1(struct get_bits_context *s)
	{
	u32 index = s->index;
	u8 result = s->buffer[index >> 3];

	#ifdef BITSTREAM_READER_LE
	result >>= index & 7;
	result &= 1;
	#else
	result <<= index & 7;
	result >>= 8 - 1;
	#endif

	index++;
	s->index = index;

	return result;
	}

	static inline u32 show_bits1(struct get_bits_context *s)
	{
	return show_bits(s, 1);
	}

	static inline void skip_bits1(struct get_bits_context *s)
	{
	skip_bits(s, 1);
	}

	/**
	* Read 0-32 bits.
	*/
	static inline u32 get_bits_long(struct get_bits_context *s, int n)
	{
	if (!n) {
	return 0;
	} else if (n <= MIN_CACHE_BITS) {
	return get_bits(s, n);
	} else {
	#ifdef BITSTREAM_READER_LE
	u32 ret = get_bits(s, 16);
	return ret \| (get_bits(s, n - 16) << 16);
	#else
	u32 ret = get_bits(s, 16) << (n - 16);
	return ret \| get_bits(s, n - 16);
	#endif
	}
	}

	/**
	* Read 0-64 bits.
	*/
	static inline u64 get_bits64(struct get_bits_context *s, int n)
	{
	if (n <= 32) {
	return get_bits_long(s, n);
	} else {
	#ifdef BITSTREAM_READER_LE
	u64 ret = get_bits_long(s, 32);
	return ret \| (u64) get_bits_long(s, n - 32) << 32;
	#else
	u64 ret = (u64) 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(struct get_bits_context *s, int n)
	{
	if (!n)
	return 0;

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

	/**
	* Show 0-32 bits.
	*/
	static inline u32 show_bits_long(struct get_bits_context *s, int n)
	{
	if (n <= MIN_CACHE_BITS) {
	return show_bits(s, n);
	} else {
	struct get_bits_context gb = *s;

	return get_bits_long(&gb, n);
	}
	}

	static inline int check_marker(struct get_bits_context s, const char msg)
	{
	int bit = get_bits1(s);

	if (!bit)
	pr_err("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(struct get_bits_context *s,
	const u8 *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 = -1;
	}

	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 struct get_bits_context.
	* @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, -1 if the buffer_size would overflow.
	*/
	static inline int init_get_bits(struct get_bits_context *s,
	const u8 *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 struct get_bits_context.
	* @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, -1 if the buffer_size would overflow.
	*/
	static inline int init_get_bits8(struct get_bits_context *s,
	const u8 *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(struct get_bits_context *s,
	const u8 *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 u8 align_get_bits(struct get_bits_context 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; \
	u32 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; \
	u32 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(struct get_bits_context *s,
	int code, int n, int nb_bits, int (*table)[2])
	{
	u32 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 inline int get_vlc2(struct get_bits_context *s,
	int (*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(struct get_bits_context *gb)
	{
	int n;

	n = get_bits1(gb);
	if (n == 0)
	return 0;
	else
	return get_bits1(gb) + 1;
	}

	static inline int decode210(struct get_bits_context *gb)
	{
	if (get_bits1(gb))
	return 0;
	else
	return 2 - get_bits1(gb);
	}

	static inline int get_bits_left(struct get_bits_context *gb)
	{
	return gb->size_in_bits - get_bits_count(gb);
	}

	static inline int skip_1stop_8data_bits(struct get_bits_context *gb)
	{
	if (get_bits_left(gb) <= 0)
	return -1;

	while (get_bits1(gb)) {
	skip_bits(gb, 8);
	if (get_bits_left(gb) <= 0)
	return -1;
	}

	return 0;
	}

	#endif /* AVCODEC_GET_BITS_H */