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

 /*
  * 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
  */

 #ifdef BITSTREAM_TEMPLATE_LE
 #   define BS_SUFFIX_LOWER _le
 #   define BS_SUFFIX_UPPER LE
 #else
 #   define BS_SUFFIX_LOWER _be
 #   define BS_SUFFIX_UPPER BE
 #endif

 #define BS_JOIN(x, y, z) x ## y ## z
 #define BS_JOIN3(x, y, z) BS_JOIN(x, y, z)
 #define BS_FUNC(x) BS_JOIN3(bits_, x, BS_SUFFIX_LOWER)

 #define BSCTX BS_JOIN3(Bitstream, Context, BS_SUFFIX_UPPER)

 typedef struct BSCTX {
     uint64_t bits;       // stores bits read from the buffer
     const uint8_t *buffer, *buffer_end;
     const uint8_t *ptr;  // pointer to the position inside a buffer
     unsigned bits_valid; // number of bits left in bits field
     unsigned size_in_bits;
 } BSCTX;

 /**
  * @return
  * - 0 on successful refill
  * - a negative number when bitstream end is hit
  *
  * Always succeeds when UNCHECKED_BITSTREAM_READER is enabled.
  */
 static inline int BS_FUNC(priv_refill_64)(BSCTX *bc)
 {
 #if !UNCHECKED_BITSTREAM_READER
     if (bc->ptr >= bc->buffer_end)
         return -1;
 #endif

 #ifdef BITSTREAM_TEMPLATE_LE
     bc->bits       = AV_RL64(bc->ptr);
 #else
     bc->bits       = AV_RB64(bc->ptr);
 #endif
     bc->ptr       += 8;
     bc->bits_valid = 64;

     return 0;
 }

 /**
  * @return
  * - 0 on successful refill
  * - a negative number when bitstream end is hit
  *
  * Always succeeds when UNCHECKED_BITSTREAM_READER is enabled.
  */
 static inline int BS_FUNC(priv_refill_32)(BSCTX *bc)
 {
 #if !UNCHECKED_BITSTREAM_READER
     if (bc->ptr >= bc->buffer_end)
         return -1;
 #endif

 #ifdef BITSTREAM_TEMPLATE_LE
     bc->bits      |= (uint64_t)AV_RL32(bc->ptr) << bc->bits_valid;
 #else
     bc->bits      |= (uint64_t)AV_RB32(bc->ptr) << (32 - bc->bits_valid);
 #endif
     bc->ptr        += 4;
     bc->bits_valid += 32;

     return 0;
 }

 /**
  * Initialize BitstreamContext.
  * @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 bits 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 BS_FUNC(init)(BSCTX *bc, const uint8_t *buffer,
                                      unsigned int bit_size)
 {
     unsigned int buffer_size;

     if (bit_size > INT_MAX - 7 || !buffer) {
         bc->buffer     = NULL;
         bc->ptr        = NULL;
         bc->bits_valid = 0;
         return AVERROR_INVALIDDATA;
     }

     buffer_size = (bit_size + 7) >> 3;

     bc->buffer       = buffer;
     bc->buffer_end   = buffer + buffer_size;
     bc->ptr          = bc->buffer;
     bc->size_in_bits = bit_size;
     bc->bits_valid   = 0;
     bc->bits         = 0;

     BS_FUNC(priv_refill_64)(bc);

     return 0;
 }

 /**
  * Initialize BitstreamContext.
  * @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 bits 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 BS_FUNC(init8)(BSCTX *bc, const uint8_t *buffer,
                                       unsigned int byte_size)
 {
     if (byte_size > INT_MAX / 8)
         return AVERROR_INVALIDDATA;
     return BS_FUNC(init)(bc, buffer, byte_size * 8);
 }

 /**
  * Return number of bits already read.
  */
 static inline int BS_FUNC(tell)(const BSCTX *bc)
 {
     return (bc->ptr - bc->buffer) * 8 - bc->bits_valid;
 }

 /**
  * Return buffer size in bits.
  */
 static inline int BS_FUNC(size)(const BSCTX *bc)
 {
     return bc->size_in_bits;
 }

 /**
  * Return the number of the bits left in a buffer.
  */
 static inline int BS_FUNC(left)(const BSCTX *bc)
 {
     return (bc->buffer - bc->ptr) * 8 + bc->size_in_bits + bc->bits_valid;
 }

 static inline uint64_t BS_FUNC(priv_val_show)(BSCTX *bc, unsigned int n)
 {
     av_assert2(n > 0 && n <= 64);

 #ifdef BITSTREAM_TEMPLATE_LE
     return bc->bits & (UINT64_MAX >> (64 - n));
 #else
     return bc->bits >> (64 - n);
 #endif
 }

 static inline void BS_FUNC(priv_skip_remaining)(BSCTX *bc, unsigned int n)
 {
 #ifdef BITSTREAM_TEMPLATE_LE
     bc->bits >>= n;
 #else
     bc->bits <<= n;
 #endif
     bc->bits_valid -= n;
 }

 static inline uint64_t BS_FUNC(priv_val_get)(BSCTX *bc, unsigned int n)
 {
     uint64_t ret;

     av_assert2(n > 0 && n < 64);

     ret = BS_FUNC(priv_val_show)(bc, n);
     BS_FUNC(priv_skip_remaining)(bc, n);

     return ret;
 }

 /**
  * Return one bit from the buffer.
  */
 static inline unsigned int BS_FUNC(read_bit)(BSCTX *bc)
 {
     if (!bc->bits_valid && BS_FUNC(priv_refill_64)(bc) < 0)
         return 0;

     return BS_FUNC(priv_val_get)(bc, 1);
 }

 /**
  * Return n bits from the buffer, n has to be in the 1-32 range.
  * May be faster than bits_read() when n is not a compile-time constant and is
  * known to be non-zero;
  */
 static inline uint32_t BS_FUNC(read_nz)(BSCTX *bc, unsigned int n)
 {
     av_assert2(n > 0 && n <= 32);

     if (n > bc->bits_valid) {
         if (BS_FUNC(priv_refill_32)(bc) < 0)
             bc->bits_valid = n;
     }

     return BS_FUNC(priv_val_get)(bc, n);
 }

 /**
  * Return n bits from the buffer, n has to be in the 0-32  range.
  */
 static inline uint32_t BS_FUNC(read)(BSCTX *bc, unsigned int n)
 {
     av_assert2(n <= 32);

     if (!n)
         return 0;

     return BS_FUNC(read_nz)(bc, n);
 }

 /**
  * Return n bits from the buffer, n has to be in the 0-63 range.
  */
 static inline uint64_t BS_FUNC(read_63)(BSCTX *bc, unsigned int n)
 {
     uint64_t ret = 0;
     unsigned left = 0;

     av_assert2(n <= 63);

     if (!n)
         return 0;

     if (n > bc->bits_valid) {
         left = bc->bits_valid;
         n   -= left;

         if (left)
             ret = BS_FUNC(priv_val_get)(bc, left);

         if (BS_FUNC(priv_refill_64)(bc) < 0)
             bc->bits_valid = n;

     }

 #ifdef BITSTREAM_TEMPLATE_LE
     ret = BS_FUNC(priv_val_get)(bc, n) << left | ret;
 #else
     ret = BS_FUNC(priv_val_get)(bc, n) | ret << n;
 #endif

     return ret;
 }

 /**
  * Return n bits from the buffer, n has to be in the 0-64 range.
  */
 static inline uint64_t BS_FUNC(read_64)(BSCTX *bc, unsigned int n)
 {
     av_assert2(n <= 64);

     if (n == 64) {
         uint64_t ret = BS_FUNC(read_63)(bc, 63);
 #ifdef BITSTREAM_TEMPLATE_LE
         return ret | ((uint64_t)BS_FUNC(read_bit)(bc) << 63);
 #else
         return (ret << 1) | (uint64_t)BS_FUNC(read_bit)(bc);
 #endif
     }
     return BS_FUNC(read_63)(bc, n);
 }

 /**
  * Return n bits from the buffer as a signed integer, n has to be in the 1-32
  * range. May be faster than bits_read_signed() when n is not a compile-time
  * constant and is known to be non-zero;
  */
 static inline int32_t BS_FUNC(read_signed_nz)(BSCTX *bc, unsigned int n)
 {
     av_assert2(n > 0 && n <= 32);
     return sign_extend(BS_FUNC(read_nz)(bc, n), n);
 }

 /**
  * Return n bits from the buffer as a signed integer.
  * n has to be in the 0-32 range.
  */
 static inline int32_t BS_FUNC(read_signed)(BSCTX *bc, unsigned int n)
 {
     av_assert2(n <= 32);

     if (!n)
         return 0;

     return BS_FUNC(read_signed_nz)(bc, n);
 }

 /**
  * Return n bits from the buffer but do not change the buffer state.
  * n has to be in the 1-32 range. May
  */
 static inline uint32_t BS_FUNC(peek_nz)(BSCTX *bc, unsigned int n)
 {
     av_assert2(n > 0 && n <= 32);

     if (n > bc->bits_valid)
         BS_FUNC(priv_refill_32)(bc);

     return BS_FUNC(priv_val_show)(bc, n);
 }

 /**
  * Return n bits from the buffer but do not change the buffer state.
  * n has to be in the 0-32 range.
  */
 static inline uint32_t BS_FUNC(peek)(BSCTX *bc, unsigned int n)
 {
     av_assert2(n <= 32);

     if (!n)
         return 0;

     return BS_FUNC(peek_nz)(bc, n);
 }

 /**
  * Return n bits from the buffer as a signed integer, do not change the buffer
  * state. n has to be in the 1-32 range. May be faster than bits_peek_signed()
  * when n is not a compile-time constant and is known to be non-zero;
  */
 static inline int BS_FUNC(peek_signed_nz)(BSCTX *bc, unsigned int n)
 {
     av_assert2(n > 0 && n <= 32);
     return sign_extend(BS_FUNC(peek_nz)(bc, n), n);
 }

 /**
  * Return n bits from the buffer as a signed integer,
  * do not change the buffer state.
  * n has to be in the 0-32 range.
  */
 static inline int BS_FUNC(peek_signed)(BSCTX *bc, unsigned int n)
 {
     av_assert2(n <= 32);

     if (!n)
         return 0;

     return BS_FUNC(peek_signed_nz)(bc, n);
 }

 /**
  * Skip n bits in the buffer.
  */
 static inline void BS_FUNC(skip)(BSCTX *bc, unsigned int n)
 {
     if (n < bc->bits_valid)
         BS_FUNC(priv_skip_remaining)(bc, n);
     else {
         n -= bc->bits_valid;
         bc->bits       = 0;
         bc->bits_valid = 0;

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

             n -= skip * 8;
             bc->ptr += skip;
         }
         BS_FUNC(priv_refill_64)(bc);
         if (n)
             BS_FUNC(priv_skip_remaining)(bc, n);
     }
 }

 /**
  * Seek to the given bit position.
  */
 static inline void BS_FUNC(seek)(BSCTX *bc, unsigned pos)
 {
     bc->ptr        = bc->buffer;
     bc->bits       = 0;
     bc->bits_valid = 0;

     BS_FUNC(skip)(bc, pos);
 }

 /**
  * Skip bits to a byte boundary.
  */
 static inline const uint8_t *BS_FUNC(align)(BSCTX *bc)
 {
     unsigned int n = -BS_FUNC(tell)(bc) & 7;
     if (n)
         BS_FUNC(skip)(bc, n);
     return bc->buffer + (BS_FUNC(tell)(bc) >> 3);
 }

 /**
  * 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 BS_FUNC(read_xbits)(BSCTX *bc, unsigned int n)
 {
     int32_t cache = BS_FUNC(peek)(bc, 32);
     int sign = ~cache >> 31;
     BS_FUNC(priv_skip_remaining)(bc, n);

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

 /**
  * Return decoded truncated unary code for the values 0, 1, 2.
  */
 static inline int BS_FUNC(decode012)(BSCTX *bc)
 {
     if (!BS_FUNC(read_bit)(bc))
         return 0;
     else
         return BS_FUNC(read_bit)(bc) + 1;
 }

 /**
  * Return decoded truncated unary code for the values 2, 1, 0.
  */
 static inline int BS_FUNC(decode210)(BSCTX *bc)
 {
     if (BS_FUNC(read_bit)(bc))
         return 0;
     else
         return 2 - BS_FUNC(read_bit)(bc);
 }

 /* Read sign bit and flip the sign of the provided value accordingly. */
 static inline int BS_FUNC(apply_sign)(BSCTX *bc, int val)
 {
     int sign = BS_FUNC(read_signed)(bc, 1);
     return (val ^ sign) - sign;
 }

 static inline int BS_FUNC(skip_1stop_8data)(BSCTX *s)
 {
     if (BS_FUNC(left)(s) <= 0)
         return AVERROR_INVALIDDATA;

     while (BS_FUNC(read_bit)(s)) {
         BS_FUNC(skip)(s, 8);
         if (BS_FUNC(left)(s) <= 0)
             return AVERROR_INVALIDDATA;
     }

     return 0;
 }

 /**
  * Return the LUT element for the given bitstream configuration.
  */
 static inline int BS_FUNC(priv_set_idx)(BSCTX *bc, int code, int *n,
                                              int *nb_bits, const VLCElem *table)
 {
     unsigned idx;

     *nb_bits = -*n;
     idx = BS_FUNC(peek)(bc, *nb_bits) + code;
     *n = table[idx].len;

     return table[idx].sym;
 }

 /**
  * Parse a vlc code.
  * @param bits is the number of bits which will be read at once, must be
  *             identical to nb_bits in vlc_init()
  * @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
  * 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.
  */
 static inline int BS_FUNC(read_vlc)(BSCTX *bc, const VLCElem *table,
                                          int bits, int max_depth)
 {
     int nb_bits;
     unsigned idx = BS_FUNC(peek)(bc, bits);
     int code     = table[idx].sym;
     int n        = table[idx].len;

     if (max_depth > 1 && n < 0) {
         BS_FUNC(priv_skip_remaining)(bc, bits);
         code = BS_FUNC(priv_set_idx)(bc, code, &n, &nb_bits, table);
         if (max_depth > 2 && n < 0) {
             BS_FUNC(priv_skip_remaining)(bc, nb_bits);
             code = BS_FUNC(priv_set_idx)(bc, code, &n, &nb_bits, table);
         }
     }
     BS_FUNC(priv_skip_remaining)(bc, n);

     return code;
 }

 /**
  * Parse a vlc / vlc_multi code.
  * @param bits is the number of bits which will be read at once, must be
  *             identical to nb_bits in vlc_init()
  * @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
  * @param dst the parsed symbol(s) will be stored here. Up to 8 bytes are written
  * @returns number of symbols parsed
  * 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.
  */
 static inline int BS_FUNC(read_vlc_multi)(BSCTX *bc, uint8_t dst[8],
                                           const VLC_MULTI_ELEM *const Jtable,
                                           const VLCElem *const table,
                                           const int bits, const int max_depth,
                                           const int symbols_size)
 {
     unsigned idx = BS_FUNC(peek)(bc, bits);
     int ret, nb_bits, code, n = Jtable[idx].len;
     if (Jtable[idx].num) {
         AV_COPY64U(dst, Jtable[idx].val8);
         ret = Jtable[idx].num;
     } else {
         code = table[idx].sym;
         n = table[idx].len;
         if (max_depth > 1 && n < 0) {
             BS_FUNC(priv_skip_remaining)(bc, bits);
             code = BS_FUNC(priv_set_idx)(bc, code, &n, &nb_bits, table);
             if (max_depth > 2 && n < 0) {
                 BS_FUNC(priv_skip_remaining)(bc, nb_bits);
                 code = BS_FUNC(priv_set_idx)(bc, code, &n, &nb_bits, table);
             }
         }
         if (symbols_size == 1)
             *dst = code;
         else
             AV_WN16(dst, code);
         ret = n > 0;
     }
     BS_FUNC(priv_skip_remaining)(bc, n);

     return ret;
 }

 #undef BSCTX
 #undef BS_FUNC
 #undef BS_JOIN3
 #undef BS_JOIN
 #undef BS_SUFFIX_UPPER
 #undef BS_SUFFIX_LOWER
	/*
	* 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
	*/

	#ifdef BITSTREAM_TEMPLATE_LE
	# define BS_SUFFIX_LOWER _le
	# define BS_SUFFIX_UPPER LE
	#else
	# define BS_SUFFIX_LOWER _be
	# define BS_SUFFIX_UPPER BE
	#endif

	#define BS_JOIN(x, y, z) x ## y ## z
	#define BS_JOIN3(x, y, z) BS_JOIN(x, y, z)
	#define BS_FUNC(x) BS_JOIN3(bits_, x, BS_SUFFIX_LOWER)

	#define BSCTX BS_JOIN3(Bitstream, Context, BS_SUFFIX_UPPER)

	typedef struct BSCTX {
	uint64_t bits; // stores bits read from the buffer
	const uint8_t buffer, buffer_end;
	const uint8_t *ptr; // pointer to the position inside a buffer
	unsigned bits_valid; // number of bits left in bits field
	unsigned size_in_bits;
	} BSCTX;

	/**
	* @return
	* - 0 on successful refill
	* - a negative number when bitstream end is hit
	*
	* Always succeeds when UNCHECKED_BITSTREAM_READER is enabled.
	*/
	static inline int BS_FUNC(priv_refill_64)(BSCTX *bc)
	{
	#if !UNCHECKED_BITSTREAM_READER
	if (bc->ptr >= bc->buffer_end)
	return -1;
	#endif

	#ifdef BITSTREAM_TEMPLATE_LE
	bc->bits = AV_RL64(bc->ptr);
	#else
	bc->bits = AV_RB64(bc->ptr);
	#endif
	bc->ptr += 8;
	bc->bits_valid = 64;

	return 0;
	}

	/**
	* @return
	* - 0 on successful refill
	* - a negative number when bitstream end is hit
	*
	* Always succeeds when UNCHECKED_BITSTREAM_READER is enabled.
	*/
	static inline int BS_FUNC(priv_refill_32)(BSCTX *bc)
	{
	#if !UNCHECKED_BITSTREAM_READER
	if (bc->ptr >= bc->buffer_end)
	return -1;
	#endif

	#ifdef BITSTREAM_TEMPLATE_LE
	bc->bits \|= (uint64_t)AV_RL32(bc->ptr) << bc->bits_valid;
	#else
	bc->bits \|= (uint64_t)AV_RB32(bc->ptr) << (32 - bc->bits_valid);
	#endif
	bc->ptr += 4;
	bc->bits_valid += 32;

	return 0;
	}

	/**
	* Initialize BitstreamContext.
	* @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 bits 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 BS_FUNC(init)(BSCTX bc, const uint8_t buffer,
	unsigned int bit_size)
	{
	unsigned int buffer_size;

	if (bit_size > INT_MAX - 7 \|\| !buffer) {
	bc->buffer = NULL;
	bc->ptr = NULL;
	bc->bits_valid = 0;
	return AVERROR_INVALIDDATA;
	}

	buffer_size = (bit_size + 7) >> 3;

	bc->buffer = buffer;
	bc->buffer_end = buffer + buffer_size;
	bc->ptr = bc->buffer;
	bc->size_in_bits = bit_size;
	bc->bits_valid = 0;
	bc->bits = 0;

	BS_FUNC(priv_refill_64)(bc);

	return 0;
	}

	/**
	* Initialize BitstreamContext.
	* @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 bits 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 BS_FUNC(init8)(BSCTX bc, const uint8_t buffer,
	unsigned int byte_size)
	{
	if (byte_size > INT_MAX / 8)
	return AVERROR_INVALIDDATA;
	return BS_FUNC(init)(bc, buffer, byte_size * 8);
	}

	/**
	* Return number of bits already read.
	*/
	static inline int BS_FUNC(tell)(const BSCTX *bc)
	{
	return (bc->ptr - bc->buffer) * 8 - bc->bits_valid;
	}

	/**
	* Return buffer size in bits.
	*/
	static inline int BS_FUNC(size)(const BSCTX *bc)
	{
	return bc->size_in_bits;
	}

	/**
	* Return the number of the bits left in a buffer.
	*/
	static inline int BS_FUNC(left)(const BSCTX *bc)
	{
	return (bc->buffer - bc->ptr) * 8 + bc->size_in_bits + bc->bits_valid;
	}

	static inline uint64_t BS_FUNC(priv_val_show)(BSCTX *bc, unsigned int n)
	{
	av_assert2(n > 0 && n <= 64);

	#ifdef BITSTREAM_TEMPLATE_LE
	return bc->bits & (UINT64_MAX >> (64 - n));
	#else
	return bc->bits >> (64 - n);
	#endif
	}

	static inline void BS_FUNC(priv_skip_remaining)(BSCTX *bc, unsigned int n)
	{
	#ifdef BITSTREAM_TEMPLATE_LE
	bc->bits >>= n;
	#else
	bc->bits <<= n;
	#endif
	bc->bits_valid -= n;
	}

	static inline uint64_t BS_FUNC(priv_val_get)(BSCTX *bc, unsigned int n)
	{
	uint64_t ret;

	av_assert2(n > 0 && n < 64);

	ret = BS_FUNC(priv_val_show)(bc, n);
	BS_FUNC(priv_skip_remaining)(bc, n);

	return ret;
	}

	/**
	* Return one bit from the buffer.
	*/
	static inline unsigned int BS_FUNC(read_bit)(BSCTX *bc)
	{
	if (!bc->bits_valid && BS_FUNC(priv_refill_64)(bc) < 0)
	return 0;

	return BS_FUNC(priv_val_get)(bc, 1);
	}

	/**
	* Return n bits from the buffer, n has to be in the 1-32 range.
	* May be faster than bits_read() when n is not a compile-time constant and is
	* known to be non-zero;
	*/
	static inline uint32_t BS_FUNC(read_nz)(BSCTX *bc, unsigned int n)
	{
	av_assert2(n > 0 && n <= 32);

	if (n > bc->bits_valid) {
	if (BS_FUNC(priv_refill_32)(bc) < 0)
	bc->bits_valid = n;
	}

	return BS_FUNC(priv_val_get)(bc, n);
	}

	/**
	* Return n bits from the buffer, n has to be in the 0-32 range.
	*/
	static inline uint32_t BS_FUNC(read)(BSCTX *bc, unsigned int n)
	{
	av_assert2(n <= 32);

	if (!n)
	return 0;

	return BS_FUNC(read_nz)(bc, n);
	}

	/**
	* Return n bits from the buffer, n has to be in the 0-63 range.
	*/
	static inline uint64_t BS_FUNC(read_63)(BSCTX *bc, unsigned int n)
	{
	uint64_t ret = 0;
	unsigned left = 0;

	av_assert2(n <= 63);

	if (!n)
	return 0;

	if (n > bc->bits_valid) {
	left = bc->bits_valid;
	n -= left;

	if (left)
	ret = BS_FUNC(priv_val_get)(bc, left);

	if (BS_FUNC(priv_refill_64)(bc) < 0)
	bc->bits_valid = n;

	}

	#ifdef BITSTREAM_TEMPLATE_LE
	ret = BS_FUNC(priv_val_get)(bc, n) << left \| ret;
	#else
	ret = BS_FUNC(priv_val_get)(bc, n) \| ret << n;
	#endif

	return ret;
	}

	/**
	* Return n bits from the buffer, n has to be in the 0-64 range.
	*/
	static inline uint64_t BS_FUNC(read_64)(BSCTX *bc, unsigned int n)
	{
	av_assert2(n <= 64);

	if (n == 64) {
	uint64_t ret = BS_FUNC(read_63)(bc, 63);
	#ifdef BITSTREAM_TEMPLATE_LE
	return ret \| ((uint64_t)BS_FUNC(read_bit)(bc) << 63);
	#else
	return (ret << 1) \| (uint64_t)BS_FUNC(read_bit)(bc);
	#endif
	}
	return BS_FUNC(read_63)(bc, n);
	}

	/**
	* Return n bits from the buffer as a signed integer, n has to be in the 1-32
	* range. May be faster than bits_read_signed() when n is not a compile-time
	* constant and is known to be non-zero;
	*/
	static inline int32_t BS_FUNC(read_signed_nz)(BSCTX *bc, unsigned int n)
	{
	av_assert2(n > 0 && n <= 32);
	return sign_extend(BS_FUNC(read_nz)(bc, n), n);
	}

	/**
	* Return n bits from the buffer as a signed integer.
	* n has to be in the 0-32 range.
	*/
	static inline int32_t BS_FUNC(read_signed)(BSCTX *bc, unsigned int n)
	{
	av_assert2(n <= 32);

	if (!n)
	return 0;

	return BS_FUNC(read_signed_nz)(bc, n);
	}

	/**
	* Return n bits from the buffer but do not change the buffer state.
	* n has to be in the 1-32 range. May
	*/
	static inline uint32_t BS_FUNC(peek_nz)(BSCTX *bc, unsigned int n)
	{
	av_assert2(n > 0 && n <= 32);

	if (n > bc->bits_valid)
	BS_FUNC(priv_refill_32)(bc);

	return BS_FUNC(priv_val_show)(bc, n);
	}

	/**
	* Return n bits from the buffer but do not change the buffer state.
	* n has to be in the 0-32 range.
	*/
	static inline uint32_t BS_FUNC(peek)(BSCTX *bc, unsigned int n)
	{
	av_assert2(n <= 32);

	if (!n)
	return 0;

	return BS_FUNC(peek_nz)(bc, n);
	}

	/**
	* Return n bits from the buffer as a signed integer, do not change the buffer
	* state. n has to be in the 1-32 range. May be faster than bits_peek_signed()
	* when n is not a compile-time constant and is known to be non-zero;
	*/
	static inline int BS_FUNC(peek_signed_nz)(BSCTX *bc, unsigned int n)
	{
	av_assert2(n > 0 && n <= 32);
	return sign_extend(BS_FUNC(peek_nz)(bc, n), n);
	}

	/**
	* Return n bits from the buffer as a signed integer,
	* do not change the buffer state.
	* n has to be in the 0-32 range.
	*/
	static inline int BS_FUNC(peek_signed)(BSCTX *bc, unsigned int n)
	{
	av_assert2(n <= 32);

	if (!n)
	return 0;

	return BS_FUNC(peek_signed_nz)(bc, n);
	}

	/**
	* Skip n bits in the buffer.
	*/
	static inline void BS_FUNC(skip)(BSCTX *bc, unsigned int n)
	{
	if (n < bc->bits_valid)
	BS_FUNC(priv_skip_remaining)(bc, n);
	else {
	n -= bc->bits_valid;
	bc->bits = 0;
	bc->bits_valid = 0;

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

	n -= skip * 8;
	bc->ptr += skip;
	}
	BS_FUNC(priv_refill_64)(bc);
	if (n)
	BS_FUNC(priv_skip_remaining)(bc, n);
	}
	}

	/**
	* Seek to the given bit position.
	*/
	static inline void BS_FUNC(seek)(BSCTX *bc, unsigned pos)
	{
	bc->ptr = bc->buffer;
	bc->bits = 0;
	bc->bits_valid = 0;

	BS_FUNC(skip)(bc, pos);
	}

	/**
	* Skip bits to a byte boundary.
	*/
	static inline const uint8_t BS_FUNC(align)(BSCTX bc)
	{
	unsigned int n = -BS_FUNC(tell)(bc) & 7;
	if (n)
	BS_FUNC(skip)(bc, n);
	return bc->buffer + (BS_FUNC(tell)(bc) >> 3);
	}

	/**
	* 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 BS_FUNC(read_xbits)(BSCTX *bc, unsigned int n)
	{
	int32_t cache = BS_FUNC(peek)(bc, 32);
	int sign = ~cache >> 31;
	BS_FUNC(priv_skip_remaining)(bc, n);

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

	/**
	* Return decoded truncated unary code for the values 0, 1, 2.
	*/
	static inline int BS_FUNC(decode012)(BSCTX *bc)
	{
	if (!BS_FUNC(read_bit)(bc))
	return 0;
	else
	return BS_FUNC(read_bit)(bc) + 1;
	}

	/**
	* Return decoded truncated unary code for the values 2, 1, 0.
	*/
	static inline int BS_FUNC(decode210)(BSCTX *bc)
	{
	if (BS_FUNC(read_bit)(bc))
	return 0;
	else
	return 2 - BS_FUNC(read_bit)(bc);
	}

	/* Read sign bit and flip the sign of the provided value accordingly. */
	static inline int BS_FUNC(apply_sign)(BSCTX *bc, int val)
	{
	int sign = BS_FUNC(read_signed)(bc, 1);
	return (val ^ sign) - sign;
	}

	static inline int BS_FUNC(skip_1stop_8data)(BSCTX *s)
	{
	if (BS_FUNC(left)(s) <= 0)
	return AVERROR_INVALIDDATA;

	while (BS_FUNC(read_bit)(s)) {
	BS_FUNC(skip)(s, 8);
	if (BS_FUNC(left)(s) <= 0)
	return AVERROR_INVALIDDATA;
	}

	return 0;
	}

	/**
	* Return the LUT element for the given bitstream configuration.
	*/
	static inline int BS_FUNC(priv_set_idx)(BSCTX bc, int code, int n,
	int nb_bits, const VLCElem table)
	{
	unsigned idx;

	nb_bits = -n;
	idx = BS_FUNC(peek)(bc, *nb_bits) + code;
	*n = table[idx].len;

	return table[idx].sym;
	}

	/**
	* Parse a vlc code.
	* @param bits is the number of bits which will be read at once, must be
	* identical to nb_bits in vlc_init()
	* @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
	* 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.
	*/
	static inline int BS_FUNC(read_vlc)(BSCTX bc, const VLCElem table,
	int bits, int max_depth)
	{
	int nb_bits;
	unsigned idx = BS_FUNC(peek)(bc, bits);
	int code = table[idx].sym;
	int n = table[idx].len;

	if (max_depth > 1 && n < 0) {
	BS_FUNC(priv_skip_remaining)(bc, bits);
	code = BS_FUNC(priv_set_idx)(bc, code, &n, &nb_bits, table);
	if (max_depth > 2 && n < 0) {
	BS_FUNC(priv_skip_remaining)(bc, nb_bits);
	code = BS_FUNC(priv_set_idx)(bc, code, &n, &nb_bits, table);
	}
	}
	BS_FUNC(priv_skip_remaining)(bc, n);

	return code;
	}

	/**
	* Parse a vlc / vlc_multi code.
	* @param bits is the number of bits which will be read at once, must be
	* identical to nb_bits in vlc_init()
	* @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
	* @param dst the parsed symbol(s) will be stored here. Up to 8 bytes are written
	* @returns number of symbols parsed
	* 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.
	*/
	static inline int BS_FUNC(read_vlc_multi)(BSCTX *bc, uint8_t dst[8],
	const VLC_MULTI_ELEM *const Jtable,
	const VLCElem *const table,
	const int bits, const int max_depth,
	const int symbols_size)
	{
	unsigned idx = BS_FUNC(peek)(bc, bits);
	int ret, nb_bits, code, n = Jtable[idx].len;
	if (Jtable[idx].num) {
	AV_COPY64U(dst, Jtable[idx].val8);
	ret = Jtable[idx].num;
	} else {
	code = table[idx].sym;
	n = table[idx].len;
	if (max_depth > 1 && n < 0) {
	BS_FUNC(priv_skip_remaining)(bc, bits);
	code = BS_FUNC(priv_set_idx)(bc, code, &n, &nb_bits, table);
	if (max_depth > 2 && n < 0) {
	BS_FUNC(priv_skip_remaining)(bc, nb_bits);
	code = BS_FUNC(priv_set_idx)(bc, code, &n, &nb_bits, table);
	}
	}
	if (symbols_size == 1)
	*dst = code;
	else
	AV_WN16(dst, code);
	ret = n > 0;
	}
	BS_FUNC(priv_skip_remaining)(bc, n);

	return ret;
	}

	#undef BSCTX
	#undef BS_FUNC
	#undef BS_JOIN3
	#undef BS_JOIN
	#undef BS_SUFFIX_UPPER
	#undef BS_SUFFIX_LOWER