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FFmpeg/libavcodec/mqc.h
Andreas Rheinhardt b43e946b71 avcodec/mqc: Hardcode tables to save space
mqc currently initializes three arrays at runtime; each of them
has 2 * 47 elements, one is uint16_t, two are uint8_t, so that their
combined size is 8 * 47. The source data for these initializations
is contained in an array of 47 elements of size six. Said array is
only used in order to initialize the other arrays, so the savings
are just 2 * 47B. Yet this is dwarfed by the size of the code for
performing the initializations: It is 109B (GCC 10.2, x64, -O3 albeit
in an av_cold function); this does not even include the size of the
code in the callers. So just hardcode these tables.

This also fixes a data race, because the encoder always initialized
these tables during init, although they might already be used at the
same time by already running encoder/decoder instances.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2021-05-12 06:00:14 +02:00

89 lines
2.2 KiB
C

/*
* MQ-coder: structures, common and decoder functions
* Copyright (c) 2007 Kamil Nowosad
*
* 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_MQC_H
#define AVCODEC_MQC_H
/**
* MQ-coder
* @file
* @author Kamil Nowosad
*/
#include <stdint.h>
#define MQC_CX_UNI 17
#define MQC_CX_RL 18
extern const uint16_t ff_mqc_qe[2 * 47];
extern const uint8_t ff_mqc_nlps[2 * 47];
extern const uint8_t ff_mqc_nmps[2 * 47];
typedef struct MqcState {
uint8_t *bp, *bpstart;
unsigned int a;
unsigned int c;
unsigned int ct;
uint8_t cx_states[19];
int raw;
} MqcState;
/* encoder */
/** initialize the encoder */
void ff_mqc_initenc(MqcState *mqc, uint8_t *bp);
/** code bit d with context cx */
void ff_mqc_encode(MqcState *mqc, uint8_t *cxstate, int d);
/** flush the encoder [returns number of bytes encoded] */
int ff_mqc_flush(MqcState *mqc);
int ff_mqc_flush_to(MqcState *mqc, uint8_t *dst, int *dst_len);
/* decoder */
/**
* Initialize MQ-decoder.
* @param mqc MQ decoder state
* @param bp byte pointer
* @param raw raw mode
* @param reset reset states
*/
void ff_mqc_initdec(MqcState *mqc, uint8_t *bp, int raw, int reset);
/**
* MQ decoder.
* @param mqc MQ decoder state
* @param cxstate Context
* @return Decision (0 to 1)
*/
int ff_mqc_decode(MqcState *mqc, uint8_t *cxstate);
/* common */
/**
* MQ-coder context initialisations.
* @param mqc MQ-coder context
*/
void ff_mqc_init_contexts(MqcState *mqc);
#endif /* AVCODEC_MQC_H */