869 lines
24 KiB
C
Executable File
869 lines
24 KiB
C
Executable File
/*
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* Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
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* Copyright (c) 2016 Alexandra Hájková
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* bitstream reader API header.
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*/
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#ifndef AVCODEC_GET_BITS_H
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#define AVCODEC_GET_BITS_H
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#include <stdint.h>
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#include "libavutil/common.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/log.h"
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#include "libavutil/avassert.h"
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#include "avcodec.h"
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#include "mathops.h"
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#include "vlc.h"
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/*
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* Safe bitstream reading:
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* optionally, the get_bits API can check to ensure that we
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* don't read past input buffer boundaries. This is protected
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* with CONFIG_SAFE_BITSTREAM_READER at the global level, and
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* then below that with UNCHECKED_BITSTREAM_READER at the per-
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* decoder level. This means that decoders that check internally
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* can "#define UNCHECKED_BITSTREAM_READER 1" to disable
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* overread checks.
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* Boundary checking causes a minor performance penalty so for
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* applications that won't want/need this, it can be disabled
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* globally using "#define CONFIG_SAFE_BITSTREAM_READER 0".
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*/
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#ifndef UNCHECKED_BITSTREAM_READER
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#define UNCHECKED_BITSTREAM_READER !CONFIG_SAFE_BITSTREAM_READER
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#endif
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#ifndef CACHED_BITSTREAM_READER
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#define CACHED_BITSTREAM_READER 0
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#endif
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typedef struct GetBitContext {
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const uint8_t *buffer, *buffer_end;
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#if CACHED_BITSTREAM_READER
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uint64_t cache;
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unsigned bits_left;
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#endif
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int index;
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int size_in_bits;
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int size_in_bits_plus8;
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} GetBitContext;
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static inline unsigned int get_bits(GetBitContext *s, int n);
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static inline void skip_bits(GetBitContext *s, int n);
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static inline unsigned int show_bits(GetBitContext *s, int n);
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/* Bitstream reader API docs:
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* name
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* arbitrary name which is used as prefix for the internal variables
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*
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* gb
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* getbitcontext
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*
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* OPEN_READER(name, gb)
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* load gb into local variables
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*
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* CLOSE_READER(name, gb)
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* store local vars in gb
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*
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* UPDATE_CACHE(name, gb)
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* Refill the internal cache from the bitstream.
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* After this call at least MIN_CACHE_BITS will be available.
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*
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* GET_CACHE(name, gb)
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* Will output the contents of the internal cache,
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* next bit is MSB of 32 or 64 bits (FIXME 64 bits).
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*
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* SHOW_UBITS(name, gb, num)
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* Will return the next num bits.
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*
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* SHOW_SBITS(name, gb, num)
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* Will return the next num bits and do sign extension.
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*
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* SKIP_BITS(name, gb, num)
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* Will skip over the next num bits.
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* Note, this is equivalent to SKIP_CACHE; SKIP_COUNTER.
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*
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* SKIP_CACHE(name, gb, num)
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* Will remove the next num bits from the cache (note SKIP_COUNTER
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* MUST be called before UPDATE_CACHE / CLOSE_READER).
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*
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* SKIP_COUNTER(name, gb, num)
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* Will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS).
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*
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* LAST_SKIP_BITS(name, gb, num)
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* Like SKIP_BITS, to be used if next call is UPDATE_CACHE or CLOSE_READER.
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*
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* BITS_LEFT(name, gb)
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* Return the number of bits left
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*
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* For examples see get_bits, show_bits, skip_bits, get_vlc.
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*/
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#if CACHED_BITSTREAM_READER
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# define MIN_CACHE_BITS 64
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#elif defined LONG_BITSTREAM_READER
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# define MIN_CACHE_BITS 32
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#else
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# define MIN_CACHE_BITS 25
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#endif
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#if !CACHED_BITSTREAM_READER
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#define OPEN_READER_NOSIZE(name, gb) \
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unsigned int name ## _index = (gb)->index; \
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unsigned int av_unused name ## _cache
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#if UNCHECKED_BITSTREAM_READER
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#define OPEN_READER(name, gb) OPEN_READER_NOSIZE(name, gb)
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#define BITS_AVAILABLE(name, gb) 1
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#else
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#define OPEN_READER(name, gb) \
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OPEN_READER_NOSIZE(name, gb); \
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unsigned int name ## _size_plus8 = (gb)->size_in_bits_plus8
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#define BITS_AVAILABLE(name, gb) name ## _index < name ## _size_plus8
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#endif
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#define CLOSE_READER(name, gb) (gb)->index = name ## _index
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# ifdef LONG_BITSTREAM_READER
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# define UPDATE_CACHE_LE(name, gb) name ## _cache = \
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AV_RL64((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
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# define UPDATE_CACHE_BE(name, gb) name ## _cache = \
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AV_RB64((gb)->buffer + (name ## _index >> 3)) >> (32 - (name ## _index & 7))
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#else
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# define UPDATE_CACHE_LE(name, gb) name ## _cache = \
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AV_RL32((gb)->buffer + (name ## _index >> 3)) >> (name ## _index & 7)
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# define UPDATE_CACHE_BE(name, gb) name ## _cache = \
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AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7)
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#endif
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#ifdef BITSTREAM_READER_LE
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# define UPDATE_CACHE(name, gb) UPDATE_CACHE_LE(name, gb)
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# define SKIP_CACHE(name, gb, num) name ## _cache >>= (num)
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#else
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# define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb)
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# define SKIP_CACHE(name, gb, num) name ## _cache <<= (num)
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#endif
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#if UNCHECKED_BITSTREAM_READER
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# define SKIP_COUNTER(name, gb, num) name ## _index += (num)
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#else
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# define SKIP_COUNTER(name, gb, num) \
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name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num))
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#endif
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#define BITS_LEFT(name, gb) ((int)((gb)->size_in_bits - name ## _index))
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#define SKIP_BITS(name, gb, num) \
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do { \
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SKIP_CACHE(name, gb, num); \
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SKIP_COUNTER(name, gb, num); \
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} while (0)
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#define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
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#define SHOW_UBITS_LE(name, gb, num) zero_extend(name ## _cache, num)
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#define SHOW_SBITS_LE(name, gb, num) sign_extend(name ## _cache, num)
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#define SHOW_UBITS_BE(name, gb, num) NEG_USR32(name ## _cache, num)
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#define SHOW_SBITS_BE(name, gb, num) NEG_SSR32(name ## _cache, num)
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#ifdef BITSTREAM_READER_LE
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# define SHOW_UBITS(name, gb, num) SHOW_UBITS_LE(name, gb, num)
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# define SHOW_SBITS(name, gb, num) SHOW_SBITS_LE(name, gb, num)
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#else
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# define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num)
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# define SHOW_SBITS(name, gb, num) SHOW_SBITS_BE(name, gb, num)
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#endif
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#define GET_CACHE(name, gb) ((uint32_t) name ## _cache)
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#endif
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static inline int get_bits_count(const GetBitContext *s)
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{
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#if CACHED_BITSTREAM_READER
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return s->index - s->bits_left;
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#else
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return s->index;
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#endif
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}
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#if CACHED_BITSTREAM_READER
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static inline void refill_32(GetBitContext *s, int is_le)
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{
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#if !UNCHECKED_BITSTREAM_READER
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if (s->index >> 3 >= s->buffer_end - s->buffer)
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return;
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#endif
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if (is_le)
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s->cache = (uint64_t)AV_RL32(s->buffer + (s->index >> 3)) << s->bits_left | s->cache;
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else
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s->cache = s->cache | (uint64_t)AV_RB32(s->buffer + (s->index >> 3)) << (32 - s->bits_left);
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s->index += 32;
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s->bits_left += 32;
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}
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static inline void refill_64(GetBitContext *s, int is_le)
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{
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#if !UNCHECKED_BITSTREAM_READER
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if (s->index >> 3 >= s->buffer_end - s->buffer)
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return;
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#endif
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if (is_le)
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s->cache = AV_RL64(s->buffer + (s->index >> 3));
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else
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s->cache = AV_RB64(s->buffer + (s->index >> 3));
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s->index += 64;
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s->bits_left = 64;
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}
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static inline uint64_t get_val(GetBitContext *s, unsigned n, int is_le)
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{
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uint64_t ret;
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av_assert2(n>0 && n<=63);
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if (is_le) {
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ret = s->cache & ((UINT64_C(1) << n) - 1);
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s->cache >>= n;
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} else {
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ret = s->cache >> (64 - n);
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s->cache <<= n;
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}
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s->bits_left -= n;
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return ret;
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}
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static inline unsigned show_val(const GetBitContext *s, unsigned n)
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{
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#ifdef BITSTREAM_READER_LE
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return s->cache & ((UINT64_C(1) << n) - 1);
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#else
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return s->cache >> (64 - n);
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#endif
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}
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#endif
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/**
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* Skips the specified number of bits.
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* @param n the number of bits to skip,
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* For the UNCHECKED_BITSTREAM_READER this must not cause the distance
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* from the start to overflow int32_t. Staying within the bitstream + padding
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* is sufficient, too.
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*/
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static inline void skip_bits_long(GetBitContext *s, int n)
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{
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#if CACHED_BITSTREAM_READER
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skip_bits(s, n);
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#else
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#if UNCHECKED_BITSTREAM_READER
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s->index += n;
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#else
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s->index += av_clip(n, -s->index, s->size_in_bits_plus8 - s->index);
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#endif
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#endif
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}
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#if CACHED_BITSTREAM_READER
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static inline void skip_remaining(GetBitContext *s, unsigned n)
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{
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#ifdef BITSTREAM_READER_LE
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s->cache >>= n;
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#else
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s->cache <<= n;
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#endif
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s->bits_left -= n;
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}
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#endif
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/**
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* Read MPEG-1 dc-style VLC (sign bit + mantissa with no MSB).
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* if MSB not set it is negative
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* @param n length in bits
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*/
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static inline int get_xbits(GetBitContext *s, int n)
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{
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#if CACHED_BITSTREAM_READER
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int32_t cache = show_bits(s, 32);
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int sign = ~cache >> 31;
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skip_remaining(s, n);
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return ((((uint32_t)(sign ^ cache)) >> (32 - n)) ^ sign) - sign;
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#else
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register int sign;
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register int32_t cache;
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OPEN_READER(re, s);
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av_assert2(n>0 && n<=25);
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UPDATE_CACHE(re, s);
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cache = GET_CACHE(re, s);
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sign = ~cache >> 31;
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LAST_SKIP_BITS(re, s, n);
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CLOSE_READER(re, s);
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return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
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#endif
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}
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#if !CACHED_BITSTREAM_READER
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static inline int get_xbits_le(GetBitContext *s, int n)
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{
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register int sign;
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register int32_t cache;
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OPEN_READER(re, s);
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av_assert2(n>0 && n<=25);
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UPDATE_CACHE_LE(re, s);
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cache = GET_CACHE(re, s);
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sign = sign_extend(~cache, n) >> 31;
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LAST_SKIP_BITS(re, s, n);
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CLOSE_READER(re, s);
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return (zero_extend(sign ^ cache, n) ^ sign) - sign;
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}
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#endif
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static inline int get_sbits(GetBitContext *s, int n)
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{
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register int tmp;
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#if CACHED_BITSTREAM_READER
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av_assert2(n>0 && n<=25);
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tmp = sign_extend(get_bits(s, n), n);
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#else
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OPEN_READER(re, s);
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av_assert2(n>0 && n<=25);
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UPDATE_CACHE(re, s);
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tmp = SHOW_SBITS(re, s, n);
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LAST_SKIP_BITS(re, s, n);
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CLOSE_READER(re, s);
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#endif
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return tmp;
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}
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/**
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* Read 1-25 bits.
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*/
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static inline unsigned int get_bits(GetBitContext *s, int n)
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{
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register unsigned int tmp;
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#if CACHED_BITSTREAM_READER
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av_assert2(n>0 && n<=32);
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if (n > s->bits_left) {
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#ifdef BITSTREAM_READER_LE
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refill_32(s, 1);
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#else
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refill_32(s, 0);
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#endif
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if (s->bits_left < 32)
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s->bits_left = n;
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}
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#ifdef BITSTREAM_READER_LE
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tmp = get_val(s, n, 1);
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#else
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tmp = get_val(s, n, 0);
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#endif
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#else
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OPEN_READER(re, s);
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av_assert2(n>0 && n<=25);
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UPDATE_CACHE(re, s);
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tmp = SHOW_UBITS(re, s, n);
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LAST_SKIP_BITS(re, s, n);
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CLOSE_READER(re, s);
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#endif
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av_assert2(tmp < UINT64_C(1) << n);
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return tmp;
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}
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/**
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* Read 0-25 bits.
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*/
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static av_always_inline int get_bitsz(GetBitContext *s, int n)
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{
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return n ? get_bits(s, n) : 0;
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}
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static inline unsigned int get_bits_le(GetBitContext *s, int n)
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{
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#if CACHED_BITSTREAM_READER
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av_assert2(n>0 && n<=32);
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if (n > s->bits_left) {
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refill_32(s, 1);
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if (s->bits_left < 32)
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s->bits_left = n;
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}
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return get_val(s, n, 1);
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#else
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register int tmp;
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OPEN_READER(re, s);
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av_assert2(n>0 && n<=25);
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UPDATE_CACHE_LE(re, s);
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tmp = SHOW_UBITS_LE(re, s, n);
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LAST_SKIP_BITS(re, s, n);
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CLOSE_READER(re, s);
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return tmp;
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#endif
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}
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/**
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* Show 1-25 bits.
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*/
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static inline unsigned int show_bits(GetBitContext *s, int n)
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{
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register unsigned int tmp;
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#if CACHED_BITSTREAM_READER
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if (n > s->bits_left)
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#ifdef BITSTREAM_READER_LE
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refill_32(s, 1);
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#else
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refill_32(s, 0);
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#endif
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tmp = show_val(s, n);
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#else
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OPEN_READER_NOSIZE(re, s);
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av_assert2(n>0 && n<=25);
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UPDATE_CACHE(re, s);
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tmp = SHOW_UBITS(re, s, n);
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#endif
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return tmp;
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}
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static inline void skip_bits(GetBitContext *s, int n)
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{
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#if CACHED_BITSTREAM_READER
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if (n < s->bits_left)
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skip_remaining(s, n);
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else {
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n -= s->bits_left;
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s->cache = 0;
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s->bits_left = 0;
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if (n >= 64) {
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unsigned skip = (n / 8) * 8;
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n -= skip;
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s->index += skip;
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}
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#ifdef BITSTREAM_READER_LE
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refill_64(s, 1);
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#else
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refill_64(s, 0);
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#endif
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if (n)
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skip_remaining(s, n);
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}
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#else
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OPEN_READER(re, s);
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LAST_SKIP_BITS(re, s, n);
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CLOSE_READER(re, s);
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#endif
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}
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static inline unsigned int get_bits1(GetBitContext *s)
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{
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#if CACHED_BITSTREAM_READER
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if (!s->bits_left)
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#ifdef BITSTREAM_READER_LE
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refill_64(s, 1);
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#else
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refill_64(s, 0);
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#endif
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#ifdef BITSTREAM_READER_LE
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return get_val(s, 1, 1);
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#else
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|
return get_val(s, 1, 0);
|
|
#endif
|
|
#else
|
|
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;
|
|
#endif
|
|
}
|
|
|
|
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;
|
|
#if CACHED_BITSTREAM_READER
|
|
}
|
|
return get_bits(s, n);
|
|
#else
|
|
} else if (n <= MIN_CACHE_BITS) {
|
|
return get_bits(s, n);
|
|
} 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);
|
|
}
|
|
|
|
/**
|
|
* Show 0-32 bits.
|
|
*/
|
|
static inline unsigned int show_bits_long(GetBitContext *s, int n)
|
|
{
|
|
if (n <= MIN_CACHE_BITS) {
|
|
return show_bits(s, n);
|
|
} else {
|
|
GetBitContext gb = *s;
|
|
return get_bits_long(&gb, n);
|
|
}
|
|
}
|
|
|
|
static inline int check_marker(void *logctx, GetBitContext *s, const char *msg)
|
|
{
|
|
int bit = get_bits1(s);
|
|
if (!bit)
|
|
av_log(logctx, AV_LOG_INFO, "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(GetBitContext *s, const uint8_t *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 = 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;
|
|
|
|
#if CACHED_BITSTREAM_READER
|
|
s->cache = 0;
|
|
s->bits_left = 0;
|
|
refill_64(s, is_le);
|
|
#endif
|
|
|
|
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 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)
|
|
{
|
|
#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 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_xe(s, buffer, byte_size * 8, 1);
|
|
}
|
|
|
|
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][0]; \
|
|
n = table[index][1]; \
|
|
\
|
|
if (max_depth > 1 && n < 0) { \
|
|
LAST_SKIP_BITS(name, gb, bits); \
|
|
UPDATE_CACHE(name, gb); \
|
|
\
|
|
nb_bits = -n; \
|
|
\
|
|
index = SHOW_UBITS(name, gb, nb_bits) + code; \
|
|
code = table[index][0]; \
|
|
n = table[index][1]; \
|
|
if (max_depth > 2 && n < 0) { \
|
|
LAST_SKIP_BITS(name, gb, nb_bits); \
|
|
UPDATE_CACHE(name, gb); \
|
|
\
|
|
nb_bits = -n; \
|
|
\
|
|
index = SHOW_UBITS(name, gb, nb_bits) + code; \
|
|
code = table[index][0]; \
|
|
n = table[index][1]; \
|
|
} \
|
|
} \
|
|
SKIP_BITS(name, gb, n); \
|
|
} while (0)
|
|
|
|
#define GET_RL_VLC(level, run, name, gb, table, bits, \
|
|
max_depth, need_update) \
|
|
do { \
|
|
int n, nb_bits; \
|
|
unsigned int index; \
|
|
\
|
|
index = SHOW_UBITS(name, gb, bits); \
|
|
level = table[index].level; \
|
|
n = table[index].len; \
|
|
\
|
|
if (max_depth > 1 && n < 0) { \
|
|
SKIP_BITS(name, gb, bits); \
|
|
if (need_update) { \
|
|
UPDATE_CACHE(name, gb); \
|
|
} \
|
|
\
|
|
nb_bits = -n; \
|
|
\
|
|
index = SHOW_UBITS(name, gb, nb_bits) + level; \
|
|
level = table[index].level; \
|
|
n = table[index].len; \
|
|
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(GetBitContext *s, int code, int *n, int *nb_bits,
|
|
VLC_TYPE (*table)[2])
|
|
{
|
|
unsigned 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 av_always_inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
|
|
int bits, int max_depth)
|
|
{
|
|
#if CACHED_BITSTREAM_READER
|
|
int nb_bits;
|
|
unsigned idx = show_bits(s, bits);
|
|
int code = table[idx][0];
|
|
int n = table[idx][1];
|
|
|
|
if (max_depth > 1 && n < 0) {
|
|
skip_remaining(s, bits);
|
|
code = set_idx(s, code, &n, &nb_bits, table);
|
|
if (max_depth > 2 && n < 0) {
|
|
skip_remaining(s, nb_bits);
|
|
code = set_idx(s, code, &n, &nb_bits, table);
|
|
}
|
|
}
|
|
skip_remaining(s, n);
|
|
|
|
return code;
|
|
#else
|
|
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;
|
|
#endif
|
|
}
|
|
|
|
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 /* AVCODEC_GET_BITS_H */
|