aom_dsp/entenc.h

/*
 * Copyright (c) 2021, Alliance for Open Media. All rights reserved
 *
 * This source code is subject to the terms of the BSD 3-Clause Clear License
 * and the Alliance for Open Media Patent License 1.0. If the BSD 3-Clause Clear
 * License was not distributed with this source code in the LICENSE file, you
 * can obtain it at aomedia.org/license/software-license/bsd-3-c-c/.  If the
 * Alliance for Open Media Patent License 1.0 was not distributed with this
 * source code in the PATENTS file, you can obtain it at
 * aomedia.org/license/patent-license/.
 */

#ifndef AOM_AOM_DSP_ENTENC_H_
#define AOM_AOM_DSP_ENTENC_H_
#include <stddef.h>
#include "aom_dsp/entcode.h"

#ifdef __cplusplus
extern "C" {
#endif

typedef struct od_ec_enc od_ec_enc;

#define OD_MEASURE_EC_OVERHEAD (0)

/*The entropy encoder context.*/
struct od_ec_enc {
  /*Buffered output.
    This contains only the raw bits until the final call to od_ec_enc_done(),
     where all the arithmetic-coded data gets prepended to it.*/
  unsigned char *buf;
  /*The size of the buffer.*/
  uint32_t storage;
  /*A buffer for output bytes with their associated carry flags.*/
  uint16_t *precarry_buf;
  /*The size of the pre-carry buffer.*/
  uint32_t precarry_storage;
  /*The offset at which the next entropy-coded byte will be written.*/
  uint32_t offs;
  /*The low end of the current range.*/
  od_ec_window low;
  /*The number of values in the current range.*/
  uint16_t rng;
  /*The number of bits of data in the current value.*/
  int16_t cnt;
  /*Nonzero if an error occurred.*/
  int error;
#if OD_MEASURE_EC_OVERHEAD
  double entropy;
  int nb_symbols;
#endif
};

/*See entenc.c for further documentation.*/

void od_ec_enc_init(od_ec_enc *enc, uint32_t size) OD_ARG_NONNULL(1);
void od_ec_enc_reset(od_ec_enc *enc) OD_ARG_NONNULL(1);
void od_ec_enc_clear(od_ec_enc *enc) OD_ARG_NONNULL(1);

void od_ec_encode_bool_bypass(od_ec_enc *enc, int val) OD_ARG_NONNULL(1);
void od_ec_encode_literal_bypass(od_ec_enc *enc, int val, int n_bits)
    OD_ARG_NONNULL(1);
void od_ec_encode_bool_q15(od_ec_enc *enc, int val, unsigned f_q15)
    OD_ARG_NONNULL(1);
void od_ec_encode_cdf_q15(od_ec_enc *enc, int s, const uint16_t *cdf, int nsyms)
    OD_ARG_NONNULL(1) OD_ARG_NONNULL(3);

void od_ec_enc_bits(od_ec_enc *enc, uint32_t fl, unsigned ftb)
    OD_ARG_NONNULL(1);

void od_ec_enc_patch_initial_bits(od_ec_enc *enc, unsigned val, int nbits)
    OD_ARG_NONNULL(1);
OD_WARN_UNUSED_RESULT unsigned char *od_ec_enc_done(od_ec_enc *enc,
                                                    uint32_t *nbytes)
    OD_ARG_NONNULL(1) OD_ARG_NONNULL(2);

OD_WARN_UNUSED_RESULT int od_ec_enc_tell(const od_ec_enc *enc)
    OD_ARG_NONNULL(1);
OD_WARN_UNUSED_RESULT uint64_t od_ec_enc_tell_frac(const od_ec_enc *enc)
    OD_ARG_NONNULL(1);

void od_ec_enc_checkpoint(od_ec_enc *dst, const od_ec_enc *src);
void od_ec_enc_rollback(od_ec_enc *dst, const od_ec_enc *src);

#ifdef __cplusplus
}  // extern "C"
#endif

#endif  // AOM_AOM_DSP_ENTENC_H_