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FFmpeg/libavcodec/vlc.h

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/*
* 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
*/
#ifndef AVCODEC_VLC_H
#define AVCODEC_VLC_H
#include <stddef.h>
#include <stdint.h>
#include "libavutil/macros.h"
#define VLC_MULTI_MAX_SYMBOLS 6
// When changing this, be sure to also update tableprint_vlc.h accordingly.
typedef int16_t VLCBaseType;
typedef struct VLCElem {
VLCBaseType sym, len;
} VLCElem;
typedef struct VLC {
int bits;
VLCElem *table;
int table_size, table_allocated;
} VLC;
typedef struct VLC_MULTI_ELEM {
union {
uint8_t val8[VLC_MULTI_MAX_SYMBOLS];
uint16_t val16[VLC_MULTI_MAX_SYMBOLS / 2];
};
int8_t len; // -31,32
uint8_t num;
} VLC_MULTI_ELEM;
typedef struct VLC_MULTI {
VLC_MULTI_ELEM *table;
int table_size, table_allocated;
} VLC_MULTI;
typedef struct RL_VLC_ELEM {
int16_t level;
int8_t len;
uint8_t run;
} RL_VLC_ELEM;
#define vlc_init(vlc, nb_bits, nb_codes, \
bits, bits_wrap, bits_size, \
codes, codes_wrap, codes_size, \
flags) \
ff_vlc_init_sparse(vlc, nb_bits, nb_codes, \
bits, bits_wrap, bits_size, \
codes, codes_wrap, codes_size, \
NULL, 0, 0, flags)
/**
* Build VLC decoding tables suitable for use with get_vlc2().
*
* @param[in,out] vlc The VLC to be initialized; table and table_allocated
* must have been set when initializing a static VLC,
* otherwise this will be treated as uninitialized.
* @param[in] nb_bits The number of bits to use for the VLC table;
* higher values take up more memory and cache, but
* allow to read codes with fewer reads.
* Corresponds to the `bits` parameter of get_vlc2().
* @param[in] nb_codes The number of provided bits, codes and (if supplied)
* symbol entries.
* @param[in] bits The lengths (in bits) of the codes. Entries > 0
* correspond to valid codes; entries == 0 will be skipped.
* @param[in] bits_wrap Stride (in bytes) of the bits table.
* @param[in] codes_size Size of the bits. 1, 2 and 4 are supported.
* @param[in] codes Table which gives the bit pattern of of each vlc code.
* @param[in] codes_wrap Stride (in bytes) of the codes table.
* @param[in] codes_size Size of the codes. 1, 2 and 4 are supported.
* @param[in] symbols The symbols, i.e. what is returned from get_vlc2()
* when the corresponding code is encountered.
* May be NULL, then 0, 1, 2, 3, 4,... will be used.
* @param[in] symbols_wrap Stride (in bytes) of the symbols table.
* @param[in] symbols_size Size of the symbols. 1 and 2 are supported.
* @param[in] flags A combination of the VLC_INIT_* flags.
*
* 'wrap' and 'size' make it possible to use any memory configuration and types
* (byte/word/int) to store the 'bits', 'codes', and 'symbols' tables.
*/
int ff_vlc_init_sparse(VLC *vlc, int nb_bits, int nb_codes,
const void *bits, int bits_wrap, int bits_size,
const void *codes, int codes_wrap, int codes_size,
const void *symbols, int symbols_wrap, int symbols_size,
int flags);
/**
* Build VLC decoding tables suitable for use with get_vlc2()
*
* This function takes lengths and symbols and calculates the codes from them.
* For this the input lengths and symbols have to be sorted according to "left
* nodes in the corresponding tree first".
*
* @param[in,out] vlc The VLC to be initialized; table and table_allocated
* must have been set when initializing a static VLC,
* otherwise this will be treated as uninitialized.
* @param[in] nb_bits The number of bits to use for the VLC table;
* higher values take up more memory and cache, but
* allow to read codes with fewer reads.
* @param[in] nb_codes The number of provided length and (if supplied) symbol
* entries.
* @param[in] lens The lengths of the codes. Entries > 0 correspond to
* valid codes; entries == 0 will be skipped and entries
* with len < 0 indicate that the tree is incomplete and
* has an open end of length -len at this position.
* @param[in] lens_wrap Stride (in bytes) of the lengths.
* @param[in] symbols The symbols, i.e. what is returned from get_vlc2()
* when the corresponding code is encountered.
* May be NULL, then 0, 1, 2, 3, 4,... will be used.
* @param[in] symbols_wrap Stride (in bytes) of the symbols.
* @param[in] symbols_size Size of the symbols. 1 and 2 are supported.
* @param[in] offset An offset to apply to all the valid symbols.
* @param[in] flags A combination of the VLC_INIT_* flags; notice that
* VLC_INIT_INPUT_LE is pointless and ignored.
*/
int ff_vlc_init_from_lengths(VLC *vlc, int nb_bits, int nb_codes,
const int8_t *lens, int lens_wrap,
const void *symbols, int symbols_wrap, int symbols_size,
int offset, int flags, void *logctx);
/**
* Build VLC decoding tables suitable for use with get_vlc_multi()
*
* This function takes lengths and symbols and calculates the codes from them.
* For this the input lengths and symbols have to be sorted according to "left
* nodes in the corresponding tree first".
*
* @param[in,out] vlc The VLC to be initialized; table and table_allocated
* must have been set when initializing a static VLC,
* otherwise this will be treated as uninitialized.
* @param[in,out] multi The VLC_MULTI to be initialized; table and table_allocated
* must have been set when initializing a static VLC,
* otherwise this will be treated as uninitialized.
* @param[in] nb_bits The number of bits to use for the VLC table;
* higher values take up more memory and cache, but
* allow to read codes with fewer reads.
* @param[in] nb_elems The max possible number of elements.
* @param[in] nb_codes The number of provided length and (if supplied) symbol
* entries.
* @param[in] lens The lengths of the codes. Entries > 0 correspond to
* valid codes; entries == 0 will be skipped and entries
* with len < 0 indicate that the tree is incomplete and
* has an open end of length -len at this position.
* @param[in] lens_wrap Stride (in bytes) of the lengths.
* @param[in] symbols The symbols, i.e. what is returned from get_vlc2()
* when the corresponding code is encountered.
* May be NULL, then 0, 1, 2, 3, 4,... will be used.
* @param[in] symbols_wrap Stride (in bytes) of the symbols.
* @param[in] symbols_size Size of the symbols. 1 and 2 are supported.
* @param[in] offset An offset to apply to all the valid symbols.
* @param[in] flags A combination of the VLC_INIT_* flags; notice that
* VLC_INIT_INPUT_LE is pointless and ignored.
*/
int ff_vlc_init_multi_from_lengths(VLC *vlc, VLC_MULTI *multi, int nb_bits, int nb_elems,
int nb_codes, const int8_t *lens, int lens_wrap,
const void *symbols, int symbols_wrap, int symbols_size,
int offset, int flags, void *logctx);
void ff_vlc_free_multi(VLC_MULTI *vlc);
void ff_vlc_free(VLC *vlc);
#define VLC_INIT_USE_STATIC 1
#define VLC_INIT_STATIC_OVERLONG (2 | VLC_INIT_USE_STATIC)
/* If VLC_INIT_INPUT_LE is set, the LSB bit of the codes used to
* initialize the VLC table is the first bit to be read. */
#define VLC_INIT_INPUT_LE 4
/* If set the VLC is intended for a little endian bitstream reader. */
#define VLC_INIT_OUTPUT_LE 8
#define VLC_INIT_LE (VLC_INIT_INPUT_LE | VLC_INIT_OUTPUT_LE)
/**
* For static VLCs, the number of bits can often be hardcoded
* at each get_vlc2() callsite. Then using a full VLC would be uneconomical,
* because only VLC.table would ever be accessed after initialization.
* The following functions provide wrappers around the relevant ff_vlc_init_*
* functions suitable for said task.
*
* The ff_vlc_init_tables_* functions are intended to be used for initializing
* a series of VLCs. The user initializes a VLCInitState with the details
* about the underlying array of VLCElem; it is automatically updated by
* the ff_vlc_init_tables_* functions (i.e. table is incremented and size
* decremented by the number of elements of the current table).
* The VLC_INIT_STATIC_OVERLONG flag is also automatically added.
* These functions return a pointer to the table just initialized,
* potentially to be used in arrays of pointer to VLC tables.
*
* The ff_vlc_init_table_* functions are intended to be used for initializing
* a single VLC table, given by table and table_size. The VLC_INIT_USE_STATIC
* flag is automatically added.
*/
typedef struct VLCInitState {
VLCElem *table; ///< points to where the next VLC table will be placed
unsigned size; ///< remaining number of elements in table
} VLCInitState;
#define VLC_INIT_STATE(_table) { .table = (_table), .size = FF_ARRAY_ELEMS(_table) }
void ff_vlc_init_table_from_lengths(VLCElem table[], int table_size,
int nb_bits, int nb_codes,
const int8_t *lens, int lens_wrap,
const void *symbols, int symbols_wrap, int symbols_size,
int offset, int flags);
const VLCElem *ff_vlc_init_tables_from_lengths(VLCInitState *state,
int nb_bits, int nb_codes,
const int8_t *lens, int lens_wrap,
const void *symbols, int symbols_wrap, int symbols_size,
int offset, int flags);
void ff_vlc_init_table_sparse(VLCElem table[], int table_size,
int nb_bits, int nb_codes,
const void *bits, int bits_wrap, int bits_size,
const void *codes, int codes_wrap, int codes_size,
const void *symbols, int symbols_wrap, int symbols_size,
int flags);
const VLCElem *ff_vlc_init_tables_sparse(VLCInitState *state,
int nb_bits, int nb_codes,
const void *bits, int bits_wrap, int bits_size,
const void *codes, int codes_wrap, int codes_size,
const void *symbols, int symbols_wrap, int symbols_size,
int flags);
static inline
const VLCElem *ff_vlc_init_tables(VLCInitState *state,
int nb_bits, int nb_codes,
const void *bits, int bits_wrap, int bits_size,
const void *codes, int codes_wrap, int codes_size,
int flags)
{
return ff_vlc_init_tables_sparse(state, nb_bits, nb_codes,
bits, bits_wrap, bits_size,
codes, codes_wrap, codes_size,
NULL, 0, 0, flags);
}
#define VLC_INIT_STATIC_SPARSE_TABLE(vlc_table, nb_bits, nb_codes, \
bits, bits_wrap, bits_size, \
codes, codes_wrap, codes_size, \
symbols, symbols_wrap, symbols_size, \
flags) \
ff_vlc_init_table_sparse(vlc_table, FF_ARRAY_ELEMS(vlc_table), \
(nb_bits), (nb_codes), \
(bits), (bits_wrap), (bits_size), \
(codes), (codes_wrap), (codes_size), \
(symbols), (symbols_wrap), (symbols_size), \
(flags))
#define VLC_INIT_STATIC_TABLE(vlc_table, nb_bits, nb_codes, \
bits, bits_wrap, bits_size, \
codes, codes_wrap, codes_size, \
flags) \
ff_vlc_init_table_sparse(vlc_table, FF_ARRAY_ELEMS(vlc_table), \
(nb_bits), (nb_codes), \
(bits), (bits_wrap), (bits_size), \
(codes), (codes_wrap), (codes_size), \
NULL, 0, 0, (flags))
#define VLC_INIT_STATIC_TABLE_FROM_LENGTHS(vlc_table, nb_bits, nb_codes, \
lens, lens_wrap, \
syms, syms_wrap, syms_size, \
offset, flags) \
ff_vlc_init_table_from_lengths(vlc_table, FF_ARRAY_ELEMS(vlc_table), \
(nb_bits), (nb_codes), \
(lens), (lens_wrap), \
(syms), (syms_wrap), (syms_size), \
(offset), (flags))
#endif /* AVCODEC_VLC_H */