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193 lines
6.7 KiB
C
193 lines
6.7 KiB
C
/*
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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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/*
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* Bit order (endianness) is controlled by #defining BITSTREAM_BE and/or
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* BITSTREAM_LE before #including this header. The corresponding bitreading
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* functions are provided as bits_*_be()/bits_*_le() respectively.
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*
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* If neither or only BITSTREAM_BE is defined, then the default (unsuffixed)
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* bits_*() will resolve to the big-endian implementation. If only BITSTREAM_LE
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* is defined, little-endian will be the default.
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*
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* If both are defined, then the default can be controlled by defining at most
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* one of BITSTREAM_DEFAULT_LE/BE. When BITSTREAM_DEFAULT_* is not defined, no
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* default is provided and you must always explicitly use the _be() or _le()
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* variants.
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*/
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#ifndef AVCODEC_BITSTREAM_H
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#define AVCODEC_BITSTREAM_H
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#include <stdint.h>
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#include "config.h"
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#include "libavutil/avassert.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 "mathops.h"
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#include "vlc.h"
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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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// select the default endianness, if any
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#if defined(BITSTREAM_LE) && defined(BITSTREAM_BE)
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# if defined(BITSTREAM_DEFAULT_BE) && defined(BITSTREAM_DEFAULT_LE)
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# error "At most one of BITSTREAM_DEFAULT_BE/LE must be defined"
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# elif defined(BITSTREAM_DEFAULT_BE)
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# define BITS_DEFAULT_BE
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# elif defined(BITSTREAM_DEFAULT_LE)
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# define BITS_DEFAULT_LE
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# endif
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#elif defined(BITSTREAM_LE)
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# define BITS_DEFAULT_LE
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#else // select BE if nothing is requested explicitly
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# define BITS_DEFAULT_BE
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# define BITSTREAM_WANT_BE
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#endif
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#if defined(BITS_DEFAULT_LE)
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# define BitstreamContext BitstreamContextLE
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# define bits_init bits_init_le
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# define bits_init8 bits_init8_le
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# define bits_tell bits_tell_le
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# define bits_size bits_size_le
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# define bits_left bits_left_le
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# define bits_read_bit bits_read_bit_le
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# define bits_read_nz bits_read_nz_le
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# define bits_read bits_read_le
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# define bits_read_63 bits_read_63_le
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# define bits_read_64 bits_read_64_le
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# define bits_read_signed bits_read_signed_le
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# define bits_peek_nz bits_peek_nz_le
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# define bits_peek bits_peek_le
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# define bits_peek_signed bits_peek_signed_le
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# define bits_skip bits_skip_le
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# define bits_seek bits_seek_le
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# define bits_align bits_align_le
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# define bits_read_xbits bits_read_xbits_le
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# define bits_decode012 bits_decode012_le
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# define bits_decode210 bits_decode210_le
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# define bits_apply_sign bits_apply_sign_le
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# define bits_read_vlc bits_read_vlc_le
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#elif defined(BITS_DEFAULT_BE)
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# define BitstreamContext BitstreamContextBE
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# define bits_init bits_init_be
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# define bits_init8 bits_init8_be
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# define bits_tell bits_tell_be
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# define bits_size bits_size_be
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# define bits_left bits_left_be
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# define bits_read_bit bits_read_bit_be
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# define bits_read_nz bits_read_nz_be
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# define bits_read bits_read_be
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# define bits_read_63 bits_read_63_be
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# define bits_read_64 bits_read_64_be
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# define bits_read_signed bits_read_signed_be
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# define bits_peek_nz bits_peek_nz_be
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# define bits_peek bits_peek_be
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# define bits_peek_signed bits_peek_signed_be
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# define bits_skip bits_skip_be
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# define bits_seek bits_seek_be
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# define bits_align bits_align_be
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# define bits_read_xbits bits_read_xbits_be
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# define bits_decode012 bits_decode012_be
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# define bits_decode210 bits_decode210_be
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# define bits_apply_sign bits_apply_sign_be
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# define bits_read_vlc bits_read_vlc_be
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#endif
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#undef BITS_DEFAULT_LE
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#undef BITS_DEFAULT_BE
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#define BITS_RL_VLC(level, run, bc, table, bits, max_depth) \
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do { \
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int n, nb_bits; \
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unsigned int index = bits_peek(bc, bits); \
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level = table[index].level; \
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n = table[index].len; \
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\
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if (max_depth > 1 && n < 0) { \
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bits_skip(bc, bits); \
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\
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nb_bits = -n; \
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\
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index = bits_peek(bc, nb_bits) + level; \
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level = table[index].level; \
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n = table[index].len; \
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if (max_depth > 2 && n < 0) { \
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bits_skip(bc, nb_bits); \
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nb_bits = -n; \
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\
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index = bits_peek(bc, nb_bits) + level; \
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level = table[index].level; \
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n = table[index].len; \
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} \
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} \
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run = table[index].run; \
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bits_skip(bc, n); \
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} while (0)
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#endif /* AVCODEC_BITSTREAM_H */
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// the following is deliberately outside of the standard #include guards
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#if defined(BITSTREAM_LE) && !defined(BITSTREAM_WANT_LE)
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# define BITSTREAM_WANT_LE
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#endif
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#if defined(BITSTREAM_BE) && !defined(BITSTREAM_WANT_BE)
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# define BITSTREAM_WANT_BE
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#endif
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#if defined(BITSTREAM_WANT_LE) && !defined(AVCODEC_BITSTREAM_LE)
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#define AVCODEC_BITSTREAM_LE
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#define BITSTREAM_TEMPLATE_LE
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#include "bitstream_template.h"
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#undef BITSTREAM_TEMPLATE_LE
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#endif
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#if defined(BITSTREAM_WANT_BE) && !defined(AVCODEC_BITSTREAM_BE)
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#define AVCODEC_BITSTREAM_BE
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#include "bitstream_template.h"
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#endif
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#undef BITSTREAM_WANT_LE
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#undef BITSTREAM_WANT_BE
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