aom_dsp/entenc.h

/*
 * Copyright (c) 2001-2016, Alliance for Open Media. All rights reserved
 *
 * This source code is subject to the terms of the BSD 2 Clause License and
 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
 * was not distributed with this source code in the LICENSE file, you can
 * obtain it at www.aomedia.org/license/software. 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 www.aomedia.org/license/patent.
 */

#if !defined(_entenc_H)
#define _entenc_H (1)
#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;
  /*The offset at which the last byte containing raw bits was written.*/
  uint32_t end_offs;
  /*Bits that will be read from/written at the end.*/
  od_ec_window end_window;
  /*Number of valid bits in end_window.*/
  int nend_bits;
  /*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_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 uint32_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