mirror of
https://git.ffmpeg.org/ffmpeg.git
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288 lines
15 KiB
C
288 lines
15 KiB
C
/*
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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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#ifndef AVCODEC_VLC_H
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#define AVCODEC_VLC_H
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#include <stddef.h>
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#include <stdint.h>
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#include "libavutil/macros.h"
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#define VLC_MULTI_MAX_SYMBOLS 6
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// When changing this, be sure to also update tableprint_vlc.h accordingly.
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typedef int16_t VLCBaseType;
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typedef struct VLCElem {
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VLCBaseType sym, len;
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} VLCElem;
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typedef struct VLC {
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int bits;
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VLCElem *table;
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int table_size, table_allocated;
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} VLC;
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typedef struct VLC_MULTI_ELEM {
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uint8_t val[VLC_MULTI_MAX_SYMBOLS];
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int8_t len; // -31,32
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uint8_t num;
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} VLC_MULTI_ELEM;
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typedef struct VLC_MULTI {
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VLC_MULTI_ELEM *table;
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int table_size, table_allocated;
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} VLC_MULTI;
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typedef struct RL_VLC_ELEM {
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int16_t level;
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int8_t len;
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uint8_t run;
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} RL_VLC_ELEM;
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#define vlc_init(vlc, nb_bits, nb_codes, \
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bits, bits_wrap, bits_size, \
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codes, codes_wrap, codes_size, \
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flags) \
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ff_vlc_init_sparse(vlc, nb_bits, nb_codes, \
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bits, bits_wrap, bits_size, \
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codes, codes_wrap, codes_size, \
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NULL, 0, 0, flags)
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/**
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* Build VLC decoding tables suitable for use with get_vlc2().
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*
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* @param[in,out] vlc The VLC to be initialized; table and table_allocated
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* must have been set when initializing a static VLC,
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* otherwise this will be treated as uninitialized.
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* @param[in] nb_bits The number of bits to use for the VLC table;
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* higher values take up more memory and cache, but
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* allow to read codes with fewer reads.
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* Corresponds to the `bits` parameter of get_vlc2().
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* @param[in] nb_codes The number of provided bits, codes and (if supplied)
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* symbol entries.
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* @param[in] bits The lengths (in bits) of the codes. Entries > 0
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* correspond to valid codes; entries == 0 will be skipped.
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* @param[in] bits_wrap Stride (in bytes) of the bits table.
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* @param[in] codes_size Size of the bits. 1, 2 and 4 are supported.
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* @param[in] codes Table which gives the bit pattern of of each vlc code.
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* @param[in] codes_wrap Stride (in bytes) of the codes table.
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* @param[in] codes_size Size of the codes. 1, 2 and 4 are supported.
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* @param[in] symbols The symbols, i.e. what is returned from get_vlc2()
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* when the corresponding code is encountered.
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* May be NULL, then 0, 1, 2, 3, 4,... will be used.
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* @param[in] symbols_wrap Stride (in bytes) of the symbols table.
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* @param[in] symbols_size Size of the symbols. 1 and 2 are supported.
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* @param[in] flags A combination of the VLC_INIT_* flags.
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*
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* 'wrap' and 'size' make it possible to use any memory configuration and types
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* (byte/word/int) to store the 'bits', 'codes', and 'symbols' tables.
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*/
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int ff_vlc_init_sparse(VLC *vlc, int nb_bits, int nb_codes,
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const void *bits, int bits_wrap, int bits_size,
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const void *codes, int codes_wrap, int codes_size,
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const void *symbols, int symbols_wrap, int symbols_size,
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int flags);
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/**
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* Build VLC decoding tables suitable for use with get_vlc2()
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*
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* This function takes lengths and symbols and calculates the codes from them.
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* For this the input lengths and symbols have to be sorted according to "left
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* nodes in the corresponding tree first".
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*
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* @param[in,out] vlc The VLC to be initialized; table and table_allocated
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* must have been set when initializing a static VLC,
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* otherwise this will be treated as uninitialized.
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* @param[in] nb_bits The number of bits to use for the VLC table;
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* higher values take up more memory and cache, but
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* allow to read codes with fewer reads.
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* @param[in] nb_codes The number of provided length and (if supplied) symbol
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* entries.
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* @param[in] lens The lengths of the codes. Entries > 0 correspond to
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* valid codes; entries == 0 will be skipped and entries
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* with len < 0 indicate that the tree is incomplete and
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* has an open end of length -len at this position.
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* @param[in] lens_wrap Stride (in bytes) of the lengths.
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* @param[in] symbols The symbols, i.e. what is returned from get_vlc2()
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* when the corresponding code is encountered.
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* May be NULL, then 0, 1, 2, 3, 4,... will be used.
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* @param[in] symbols_wrap Stride (in bytes) of the symbols.
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* @param[in] symbols_size Size of the symbols. 1 and 2 are supported.
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* @param[in] offset An offset to apply to all the valid symbols.
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* @param[in] flags A combination of the VLC_INIT_* flags; notice that
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* VLC_INIT_INPUT_LE is pointless and ignored.
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*/
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int ff_vlc_init_from_lengths(VLC *vlc, int nb_bits, int nb_codes,
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const int8_t *lens, int lens_wrap,
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const void *symbols, int symbols_wrap, int symbols_size,
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int offset, int flags, void *logctx);
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/**
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* Build VLC decoding tables suitable for use with get_vlc_multi()
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*
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* This function takes lengths and symbols and calculates the codes from them.
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* For this the input lengths and symbols have to be sorted according to "left
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* nodes in the corresponding tree first".
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*
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* @param[in,out] vlc The VLC to be initialized; table and table_allocated
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* must have been set when initializing a static VLC,
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* otherwise this will be treated as uninitialized.
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* @param[in,out] multi The VLC_MULTI to be initialized; table and table_allocated
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* must have been set when initializing a static VLC,
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* otherwise this will be treated as uninitialized.
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* @param[in] nb_bits The number of bits to use for the VLC table;
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* higher values take up more memory and cache, but
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* allow to read codes with fewer reads.
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* @param[in] nb_elems The max possible number of elements.
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* @param[in] nb_codes The number of provided length and (if supplied) symbol
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* entries.
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* @param[in] lens The lengths of the codes. Entries > 0 correspond to
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* valid codes; entries == 0 will be skipped and entries
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* with len < 0 indicate that the tree is incomplete and
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* has an open end of length -len at this position.
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* @param[in] lens_wrap Stride (in bytes) of the lengths.
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* @param[in] symbols The symbols, i.e. what is returned from get_vlc2()
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* when the corresponding code is encountered.
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* May be NULL, then 0, 1, 2, 3, 4,... will be used.
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* @param[in] symbols_wrap Stride (in bytes) of the symbols.
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* @param[in] symbols_size Size of the symbols. 1 and 2 are supported.
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* @param[in] offset An offset to apply to all the valid symbols.
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* @param[in] flags A combination of the VLC_INIT_* flags; notice that
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* VLC_INIT_INPUT_LE is pointless and ignored.
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*/
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int ff_vlc_init_multi_from_lengths(VLC *vlc, VLC_MULTI *multi, int nb_bits, int nb_elems,
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int nb_codes, const int8_t *lens, int lens_wrap,
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const void *symbols, int symbols_wrap, int symbols_size,
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int offset, int flags, void *logctx);
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void ff_vlc_free_multi(VLC_MULTI *vlc);
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void ff_vlc_free(VLC *vlc);
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#define VLC_INIT_USE_STATIC 1
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#define VLC_INIT_STATIC_OVERLONG (2 | VLC_INIT_USE_STATIC)
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/* If VLC_INIT_INPUT_LE is set, the LSB bit of the codes used to
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* initialize the VLC table is the first bit to be read. */
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#define VLC_INIT_INPUT_LE 4
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/* If set the VLC is intended for a little endian bitstream reader. */
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#define VLC_INIT_OUTPUT_LE 8
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#define VLC_INIT_LE (VLC_INIT_INPUT_LE | VLC_INIT_OUTPUT_LE)
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/**
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* For static VLCs, the number of bits can often be hardcoded
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* at each get_vlc2() callsite. Then using a full VLC would be uneconomical,
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* because only VLC.table would ever be accessed after initialization.
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* The following functions provide wrappers around the relevant ff_vlc_init_*
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* functions suitable for said task.
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*
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* The ff_vlc_init_tables_* functions are intended to be used for initializing
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* a series of VLCs. The user initializes a VLCInitState with the details
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* about the underlying array of VLCElem; it is automatically updated by
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* the ff_vlc_init_tables_* functions (i.e. table is incremented and size
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* decremented by the number of elements of the current table).
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* The VLC_INIT_STATIC_OVERLONG flag is also automatically added.
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* These functions return a pointer to the table just initialized,
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* potentially to be used in arrays of pointer to VLC tables.
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*
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* The ff_vlc_init_table_* functions are intended to be used for initializing
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* a single VLC table, given by table and table_size. The VLC_INIT_USE_STATIC
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* flag is automatically added.
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*/
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typedef struct VLCInitState {
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VLCElem *table; ///< points to where the next VLC table will be placed
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unsigned size; ///< remaining number of elements in table
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} VLCInitState;
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#define VLC_INIT_STATE(_table) { .table = (_table), .size = FF_ARRAY_ELEMS(_table) }
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void ff_vlc_init_table_from_lengths(VLCElem table[], int table_size,
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int nb_bits, int nb_codes,
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const int8_t *lens, int lens_wrap,
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const void *symbols, int symbols_wrap, int symbols_size,
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int offset, int flags);
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const VLCElem *ff_vlc_init_tables_from_lengths(VLCInitState *state,
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int nb_bits, int nb_codes,
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const int8_t *lens, int lens_wrap,
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const void *symbols, int symbols_wrap, int symbols_size,
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int offset, int flags);
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void ff_vlc_init_table_sparse(VLCElem table[], int table_size,
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int nb_bits, int nb_codes,
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const void *bits, int bits_wrap, int bits_size,
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const void *codes, int codes_wrap, int codes_size,
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const void *symbols, int symbols_wrap, int symbols_size,
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int flags);
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const VLCElem *ff_vlc_init_tables_sparse(VLCInitState *state,
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int nb_bits, int nb_codes,
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const void *bits, int bits_wrap, int bits_size,
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const void *codes, int codes_wrap, int codes_size,
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const void *symbols, int symbols_wrap, int symbols_size,
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int flags);
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static inline
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const VLCElem *ff_vlc_init_tables(VLCInitState *state,
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int nb_bits, int nb_codes,
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const void *bits, int bits_wrap, int bits_size,
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const void *codes, int codes_wrap, int codes_size,
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int flags)
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{
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return ff_vlc_init_tables_sparse(state, nb_bits, nb_codes,
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bits, bits_wrap, bits_size,
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codes, codes_wrap, codes_size,
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NULL, 0, 0, flags);
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}
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#define VLC_INIT_STATIC_SPARSE_TABLE(vlc_table, nb_bits, nb_codes, \
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bits, bits_wrap, bits_size, \
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codes, codes_wrap, codes_size, \
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symbols, symbols_wrap, symbols_size, \
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flags) \
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ff_vlc_init_table_sparse(vlc_table, FF_ARRAY_ELEMS(vlc_table), \
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(nb_bits), (nb_codes), \
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(bits), (bits_wrap), (bits_size), \
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(codes), (codes_wrap), (codes_size), \
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(symbols), (symbols_wrap), (symbols_size), \
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(flags))
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#define VLC_INIT_STATIC_TABLE(vlc_table, nb_bits, nb_codes, \
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bits, bits_wrap, bits_size, \
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codes, codes_wrap, codes_size, \
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flags) \
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ff_vlc_init_table_sparse(vlc_table, FF_ARRAY_ELEMS(vlc_table), \
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(nb_bits), (nb_codes), \
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(bits), (bits_wrap), (bits_size), \
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(codes), (codes_wrap), (codes_size), \
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NULL, 0, 0, (flags))
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#define VLC_INIT_STATIC_TABLE_FROM_LENGTHS(vlc_table, nb_bits, nb_codes, \
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lens, lens_wrap, \
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syms, syms_wrap, syms_size, \
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offset, flags) \
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ff_vlc_init_table_from_lengths(vlc_table, FF_ARRAY_ELEMS(vlc_table), \
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(nb_bits), (nb_codes), \
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(lens), (lens_wrap), \
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(syms), (syms_wrap), (syms_size), \
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(offset), (flags))
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#endif /* AVCODEC_VLC_H */
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