| /* | |
| * 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/avassert.h" | |
| #include "defs.h" | |
| #include "mathops.h" | |
| #include "vlc.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 | |
| #ifndef CACHED_BITSTREAM_READER | |
| #define CACHED_BITSTREAM_READER 0 | |
| #endif | |
| #if CACHED_BITSTREAM_READER | |
| // we always want the LE implementation, to provide get_bits_le() | |
| #define BITSTREAM_LE | |
| #ifndef BITSTREAM_READER_LE | |
| # define BITSTREAM_BE | |
| # define BITSTREAM_DEFAULT_BE | |
| #endif | |
| #include "bitstream.h" | |
| #undef BITSTREAM_LE | |
| #undef BITSTREAM_BE | |
| #undef BITSTREAM_DEFAULT_BE | |
| typedef BitstreamContext GetBitContext; | |
| #define get_bits_count bits_tell | |
| #define get_bits_left bits_left | |
| #define skip_bits_long bits_skip | |
| #define skip_bits bits_skip | |
| #define get_bits bits_read_nz | |
| #define get_bitsz bits_read | |
| #define get_bits_long bits_read | |
| #define get_bits1 bits_read_bit | |
| #define get_bits64 bits_read_64 | |
| #define get_xbits bits_read_xbits | |
| #define get_sbits bits_read_signed_nz | |
| #define get_sbits_long bits_read_signed | |
| #define show_bits bits_peek | |
| #define show_bits_long bits_peek | |
| #define init_get_bits bits_init | |
| #define init_get_bits8 bits_init8 | |
| #define align_get_bits bits_align | |
| #define get_vlc2 bits_read_vlc | |
| #define get_vlc_multi bits_read_vlc_multi | |
| #define init_get_bits8_le(s, buffer, byte_size) bits_init8_le((BitstreamContextLE*)s, buffer, byte_size) | |
| #define get_bits_le(s, n) bits_read_le((BitstreamContextLE*)s, n) | |
| #define show_bits1(s) bits_peek(s, 1) | |
| #define skip_bits1(s) bits_skip(s, 1) | |
| #define skip_1stop_8data_bits bits_skip_1stop_8data | |
| #else // CACHED_BITSTREAM_READER | |
| typedef struct GetBitContext { | |
| const uint8_t *buffer, *buffer_end; | |
| int index; | |
| int size_in_bits; | |
| int size_in_bits_plus8; | |
| } GetBitContext; | |
| static inline unsigned int get_bits(GetBitContext *s, int n); | |
| static inline void skip_bits(GetBitContext *s, int n); | |
| static inline unsigned int show_bits(GetBitContext *s, int n); | |
| /* 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 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. | |
| */ | |
| #if defined LONG_BITSTREAM_READER | |
| # define MIN_CACHE_BITS 32 | |
| #else | |
| # define MIN_CACHE_BITS 25 | |
| #endif | |
| #define OPEN_READER_NOSIZE(name, gb) \ | |
| unsigned int name ## _index = (gb)->index; \ | |
| unsigned int av_unused name ## _cache | |
| #if UNCHECKED_BITSTREAM_READER | |
| #define OPEN_READER(name, gb) OPEN_READER_NOSIZE(name, gb) | |
| #define BITS_AVAILABLE(name, gb) 1 | |
| #else | |
| #define OPEN_READER(name, gb) \ | |
| OPEN_READER_NOSIZE(name, gb); \ | |
| unsigned int name ## _size_plus8 = (gb)->size_in_bits_plus8 | |
| #define BITS_AVAILABLE(name, gb) name ## _index < name ## _size_plus8 | |
| #endif | |
| #define CLOSE_READER(name, gb) (gb)->index = name ## _index | |
| #define UPDATE_CACHE_BE_EXT(name, gb, bits, dst_bits) name ## _cache = \ | |
| AV_RB ## bits((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7) >> (bits - dst_bits) | |
| #define UPDATE_CACHE_LE_EXT(name, gb, bits, dst_bits) name ## _cache = \ | |
| (uint ## dst_bits ## _t)(AV_RL ## bits((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)) | |
| /* Using these two macros ensures that 32 bits are available. */ | |
| # define UPDATE_CACHE_LE_32(name, gb) UPDATE_CACHE_LE_EXT(name, (gb), 64, 32) | |
| # define UPDATE_CACHE_BE_32(name, gb) UPDATE_CACHE_BE_EXT(name, (gb), 64, 32) | |
| # ifdef LONG_BITSTREAM_READER | |
| # define UPDATE_CACHE_LE(name, gb) UPDATE_CACHE_LE_32(name, (gb)) | |
| # define UPDATE_CACHE_BE(name, gb) UPDATE_CACHE_BE_32(name, (gb)) | |
| #else | |
| # define UPDATE_CACHE_LE(name, gb) UPDATE_CACHE_LE_EXT(name, (gb), 32, 32) | |
| # define UPDATE_CACHE_BE(name, gb) UPDATE_CACHE_BE_EXT(name, (gb), 32, 32) | |
| #endif | |
| #ifdef BITSTREAM_READER_LE | |
| # define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb) | |
| # define UPDATE_CACHE_32(name, gb) UPDATE_CACHE_LE_32(name, (gb)) | |
| # define SKIP_CACHE(name, gb, num) name ## _cache >>= (num) | |
| #else | |
| # define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb) | |
| # define UPDATE_CACHE_32(name, gb) UPDATE_CACHE_BE_32(name, (gb)) | |
| # define SKIP_CACHE(name, gb, num) name ## _cache <<= (num) | |
| #endif | |
| #if UNCHECKED_BITSTREAM_READER | |
| # define SKIP_COUNTER(name, gb, num) name ## _index += (num) | |
| #else | |
| # define SKIP_COUNTER(name, gb, num) \ | |
| name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num)) | |
| #endif | |
| #define 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 LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num) | |
| #define SHOW_UBITS_LE(name, gb, num) zero_extend(name ## _cache, num) | |
| #define SHOW_SBITS_LE(name, gb, num) sign_extend(name ## _cache, num) | |
| #define SHOW_UBITS_BE(name, gb, num) NEG_USR32(name ## _cache, num) | |
| #define SHOW_SBITS_BE(name, gb, num) NEG_SSR32(name ## _cache, num) | |
| #ifdef BITSTREAM_READER_LE | |
| # define SHOW_UBITS(name, gb, num) SHOW_UBITS_LE(name, gb, num) | |
| # define SHOW_SBITS(name, gb, num) SHOW_SBITS_LE(name, gb, num) | |
| #else | |
| # define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num) | |
| # define SHOW_SBITS(name, gb, num) SHOW_SBITS_BE(name, gb, num) | |
| #endif | |
| #define GET_CACHE(name, gb) ((uint32_t) name ## _cache) | |
| static inline int get_bits_count(const GetBitContext *s) | |
| { | |
| return s->index; | |
| } | |
| /** | |
| * 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 int32_t. Staying within the bitstream + padding | |
| * is sufficient, too. | |
| */ | |
| 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 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(GetBitContext *s, int n) | |
| { | |
| register int sign; | |
| register int32_t cache; | |
| OPEN_READER(re, s); | |
| av_assert2(n>0 && n<=25); | |
| UPDATE_CACHE(re, s); | |
| cache = GET_CACHE(re, s); | |
| sign = ~cache >> 31; | |
| LAST_SKIP_BITS(re, s, n); | |
| CLOSE_READER(re, s); | |
| return (NEG_USR32(sign ^ cache, n) ^ sign) - sign; | |
| } | |
| static inline int get_xbits_le(GetBitContext *s, int n) | |
| { | |
| register int sign; | |
| register int32_t cache; | |
| OPEN_READER(re, s); | |
| av_assert2(n>0 && n<=25); | |
| 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(GetBitContext *s, int n) | |
| { | |
| register int tmp; | |
| OPEN_READER(re, s); | |
| av_assert2(n>0 && n<=25); | |
| UPDATE_CACHE(re, s); | |
| tmp = SHOW_SBITS(re, s, n); | |
| LAST_SKIP_BITS(re, s, n); | |
| CLOSE_READER(re, s); | |
| return tmp; | |
| } | |
| /** | |
| * Read 1-25 bits. | |
| */ | |
| static inline unsigned int get_bits(GetBitContext *s, int n) | |
| { | |
| register unsigned int tmp; | |
| OPEN_READER(re, s); | |
| av_assert2(n>0 && n<=25); | |
| UPDATE_CACHE(re, s); | |
| tmp = SHOW_UBITS(re, s, n); | |
| LAST_SKIP_BITS(re, s, n); | |
| CLOSE_READER(re, s); | |
| av_assert2(tmp < UINT64_C(1) << n); | |
| return tmp; | |
| } | |
| /** | |
| * Read 0-25 bits. | |
| */ | |
| static av_always_inline int get_bitsz(GetBitContext *s, int n) | |
| { | |
| return n ? get_bits(s, n) : 0; | |
| } | |
| static inline unsigned int get_bits_le(GetBitContext *s, int n) | |
| { | |
| register int tmp; | |
| OPEN_READER(re, s); | |
| av_assert2(n>0 && n<=25); | |
| UPDATE_CACHE_LE(re, s); | |
| tmp = SHOW_UBITS_LE(re, s, n); | |
| LAST_SKIP_BITS(re, s, n); | |
| CLOSE_READER(re, s); | |
| return tmp; | |
| } | |
| /** | |
| * Show 1-25 bits. | |
| */ | |
| static inline unsigned int show_bits(GetBitContext *s, int n) | |
| { | |
| register unsigned int tmp; | |
| OPEN_READER_NOSIZE(re, s); | |
| av_assert2(n>0 && n<=25); | |
| UPDATE_CACHE(re, s); | |
| tmp = SHOW_UBITS(re, s, n); | |
| return tmp; | |
| } | |
| static inline void skip_bits(GetBitContext *s, int n) | |
| { | |
| OPEN_READER(re, s); | |
| LAST_SKIP_BITS(re, s, n); | |
| CLOSE_READER(re, s); | |
| } | |
| static inline unsigned int get_bits1(GetBitContext *s) | |
| { | |
| unsigned int index = s->index; | |
| uint8_t result = s->buffer[index >> 3]; | |
| #ifdef BITSTREAM_READER_LE | |
| result >>= index & 7; | |
| result &= 1; | |
| #else | |
| result <<= index & 7; | |
| result >>= 8 - 1; | |
| #endif | |
| #if !UNCHECKED_BITSTREAM_READER | |
| if (s->index < s->size_in_bits_plus8) | |
| #endif | |
| index++; | |
| s->index = index; | |
| return result; | |
| } | |
| static inline unsigned int show_bits1(GetBitContext *s) | |
| { | |
| return show_bits(s, 1); | |
| } | |
| static inline void skip_bits1(GetBitContext *s) | |
| { | |
| skip_bits(s, 1); | |
| } | |
| /** | |
| * Read 0-32 bits. | |
| */ | |
| static inline unsigned int get_bits_long(GetBitContext *s, int n) | |
| { | |
| av_assert2(n>=0 && n<=32); | |
| if (!n) { | |
| return 0; | |
| } else if ((!HAVE_FAST_64BIT || av_builtin_constant_p(n <= MIN_CACHE_BITS)) | |
| && n <= MIN_CACHE_BITS) { | |
| return get_bits(s, n); | |
| } else { | |
| #if HAVE_FAST_64BIT | |
| unsigned tmp; | |
| OPEN_READER(re, s); | |
| UPDATE_CACHE_32(re, s); | |
| tmp = SHOW_UBITS(re, s, n); | |
| LAST_SKIP_BITS(re, s, n); | |
| CLOSE_READER(re, s); | |
| return tmp; | |
| #else | |
| #ifdef BITSTREAM_READER_LE | |
| unsigned ret = get_bits(s, 16); | |
| return ret | (get_bits(s, n - 16) << 16); | |
| #else | |
| unsigned ret = get_bits(s, 16) << (n - 16); | |
| return ret | get_bits(s, n - 16); | |
| #endif | |
| #endif | |
| } | |
| } | |
| /** | |
| * Read 0-64 bits. | |
| */ | |
| static inline uint64_t get_bits64(GetBitContext *s, int n) | |
| { | |
| if (n <= 32) { | |
| return get_bits_long(s, n); | |
| } else { | |
| #ifdef BITSTREAM_READER_LE | |
| uint64_t ret = get_bits_long(s, 32); | |
| return ret | (uint64_t) get_bits_long(s, n - 32) << 32; | |
| #else | |
| uint64_t ret = (uint64_t) get_bits_long(s, n - 32) << 32; | |
| return ret | get_bits_long(s, 32); | |
| #endif | |
| } | |
| } | |
| /** | |
| * Read 0-32 bits as a signed integer. | |
| */ | |
| static inline int get_sbits_long(GetBitContext *s, int n) | |
| { | |
| // sign_extend(x, 0) is undefined | |
| if (!n) | |
| return 0; | |
| return sign_extend(get_bits_long(s, n), n); | |
| } | |
| /** | |
| * Read 0-64 bits as a signed integer. | |
| */ | |
| static inline int64_t get_sbits64(GetBitContext *s, int n) | |
| { | |
| // sign_extend(x, 0) is undefined | |
| if (!n) | |
| return 0; | |
| return sign_extend64(get_bits64(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); | |
| } | |
| } | |
| /** | |
| * Initialize GetBitContext. | |
| * @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, 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 - FFMAX(7, AV_INPUT_BUFFER_PADDING_SIZE*8) || bit_size < 0 || !buffer) { | |
| bit_size = 0; | |
| buffer = NULL; | |
| ret = AVERROR_INVALIDDATA; | |
| } | |
| buffer_size = (bit_size + 7) >> 3; | |
| s->buffer = buffer; | |
| s->size_in_bits = bit_size; | |
| s->size_in_bits_plus8 = bit_size + 8; | |
| s->buffer_end = buffer + buffer_size; | |
| s->index = 0; | |
| return ret; | |
| } | |
| /** | |
| * Initialize GetBitContext. | |
| * @param buffer bitstream buffer, must be 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, AVERROR_INVALIDDATA if the buffer_size would overflow. | |
| */ | |
| static inline int init_get_bits8(GetBitContext *s, const uint8_t *buffer, | |
| int byte_size) | |
| { | |
| if (byte_size > INT_MAX / 8 || byte_size < 0) | |
| byte_size = -1; | |
| return init_get_bits(s, buffer, byte_size * 8); | |
| } | |
| static inline int init_get_bits8_le(GetBitContext *s, const uint8_t *buffer, | |
| int byte_size) | |
| { | |
| if (byte_size > INT_MAX / 8 || byte_size < 0) | |
| byte_size = -1; | |
| return init_get_bits(s, buffer, byte_size * 8); | |
| } | |
| static inline const uint8_t *align_get_bits(GetBitContext *s) | |
| { | |
| int n = -get_bits_count(s) & 7; | |
| if (n) | |
| skip_bits(s, n); | |
| return s->buffer + (s->index >> 3); | |
| } | |
| /** | |
| * 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].sym; \ | |
| n = table[index].len; \ | |
| \ | |
| 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].sym; \ | |
| n = table[index].len; \ | |
| 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].sym; \ | |
| n = table[index].len; \ | |
| } \ | |
| } \ | |
| 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; \ | |
| 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) | |
| /** | |
| * 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 | |
| * @returns the code parsed or -1 if no vlc matches | |
| */ | |
| static av_always_inline int get_vlc2(GetBitContext *s, const VLCElem *table, | |
| 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 get_vlc_multi(GetBitContext *s, uint8_t *dst, | |
| const VLC_MULTI_ELEM *const Jtable, | |
| const VLCElem *const table, | |
| const int bits, const int max_depth, | |
| const int symbols_size) | |
| { | |
| dst[0] = get_vlc2(s, table, bits, max_depth); | |
| return 1; | |
| } | |
| 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); | |
| } | |
| static inline int skip_1stop_8data_bits(GetBitContext *gb) | |
| { | |
| if (get_bits_left(gb) <= 0) | |
| return AVERROR_INVALIDDATA; | |
| while (get_bits1(gb)) { | |
| skip_bits(gb, 8); | |
| if (get_bits_left(gb) <= 0) | |
| return AVERROR_INVALIDDATA; | |
| } | |
| return 0; | |
| } | |
| #endif // CACHED_BITSTREAM_READER | |
| #endif /* AVCODEC_GET_BITS_H */ |