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/*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; 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 <stdint.h>
#include "bitstream.h"
#define VLC_TYPE int16_t
typedef struct VLC {
int bits;
VLC_TYPE (*table)[2]; ///< code, bits
int table_size, table_allocated;
} VLC;
typedef struct RL_VLC_ELEM {
int16_t level;
int8_t len;
uint8_t run;
} RL_VLC_ELEM;
#define init_vlc(vlc, nb_bits, nb_codes, \
bits, bits_wrap, bits_size, \
codes, codes_wrap, codes_size, \
flags) \
ff_init_vlc_sparse(vlc, nb_bits, nb_codes, \
bits, bits_wrap, bits_size, \
codes, codes_wrap, codes_size, \
NULL, 0, 0, flags)
int ff_init_vlc_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);
void ff_free_vlc(VLC *vlc);
#define INIT_VLC_LE 2
#define INIT_VLC_USE_NEW_STATIC 4
#define INIT_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, static_size) \
do { \
static VLC_TYPE table[static_size][2]; \
(vlc)->table = table; \
(vlc)->table_allocated = static_size; \
init_vlc(vlc, bits, a, b, c, d, e, f, g, INIT_VLC_USE_NEW_STATIC); \
} while (0)
/* Return the LUT element for the given bitstream configuration. */
static inline int set_idx(BitstreamContext *bc, int code, int *n, int *nb_bits,
VLC_TYPE (*table)[2])
{
unsigned idx;
*nb_bits = -*n;
idx = bitstream_peek(bc, *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
* 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. */
static inline int bitstream_read_vlc(BitstreamContext *bc, VLC_TYPE (*table)[2],
int bits, int max_depth)
{
int nb_bits;
unsigned idx = bitstream_peek(bc, bits);
int code = table[idx][0];
int n = table[idx][1];
if (max_depth > 1 && n < 0) {
skip_remaining(bc, bits);
code = set_idx(bc, code, &n, &nb_bits, table);
if (max_depth > 2 && n < 0) {
skip_remaining(bc, nb_bits);
code = set_idx(bc, code, &n, &nb_bits, table);
}
}
skip_remaining(bc, n);
return code;
}
#define BITSTREAM_RL_VLC(level, run, bc, table, bits, max_depth) \
do { \
int n, nb_bits; \
unsigned index = bitstream_peek(bc, bits); \
level = table[index].level; \
n = table[index].len; \
\
if (max_depth > 1 && n < 0) { \
bitstream_skip(bc, bits); \
\
nb_bits = -n; \
\
index = bitstream_peek(bc, nb_bits) + level; \
level = table[index].level; \
n = table[index].len; \
if (max_depth > 2 && n < 0) { \
bitstream_skip(bc, nb_bits); \
nb_bits = -n; \
\
index = bitstream_peek(bc, nb_bits) + level; \
level = table[index].level; \
n = table[index].len; \
} \
} \
run = table[index].run; \
bitstream_skip(bc, n); \
} while (0)
#endif /* AVCODEC_VLC_H */
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