/* * 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.Lines 1–500 of 574. 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/* * 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.