/* | |

* 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. | |

*/ | |

#ifndef AOM_AOM_DSP_ENTDEC_H_ | |

#define AOM_AOM_DSP_ENTDEC_H_ | |

#include <limits.h> | |

#include "aom_dsp/entcode.h" | |

#ifdef __cplusplus | |

extern "C" { | |

#endif | |

typedef struct od_ec_dec od_ec_dec; | |

#if defined(OD_ACCOUNTING) && OD_ACCOUNTING | |

#define OD_ACC_STR , char *acc_str | |

#define od_ec_dec_bits(dec, ftb, str) od_ec_dec_bits_(dec, ftb, str) | |

#else | |

#define OD_ACC_STR | |

#define od_ec_dec_bits(dec, ftb, str) od_ec_dec_bits_(dec, ftb) | |

#endif | |

/*The entropy decoder context.*/ | |

struct od_ec_dec { | |

/*The start of the current input buffer.*/ | |

const unsigned char *buf; | |

/*An offset used to keep track of tell after reaching the end of the stream. | |

This is constant throughout most of the decoding process, but becomes | |

important once we hit the end of the buffer and stop incrementing bptr | |

(and instead pretend cnt has lots of bits).*/ | |

int32_t tell_offs; | |

/*The end of the current input buffer.*/ | |

const unsigned char *end; | |

/*The read pointer for the entropy-coded bits.*/ | |

const unsigned char *bptr; | |

/*The difference between the high end of the current range, (low + rng), and | |

the coded value, minus 1. | |

This stores up to OD_EC_WINDOW_SIZE bits of that difference, but the | |

decoder only uses the top 16 bits of the window to decode the next symbol. | |

As we shift up during renormalization, if we don't have enough bits left in | |

the window to fill the top 16, we'll read in more bits of the coded | |

value.*/ | |

od_ec_window dif; | |

/*The number of values in the current range.*/ | |

uint16_t rng; | |

/*The number of bits of data in the current value.*/ | |

int16_t cnt; | |

}; | |

/*See entdec.c for further documentation.*/ | |

void od_ec_dec_init(od_ec_dec *dec, const unsigned char *buf, uint32_t storage) | |

OD_ARG_NONNULL(1) OD_ARG_NONNULL(2); | |

OD_WARN_UNUSED_RESULT int od_ec_decode_bool_q15(od_ec_dec *dec, unsigned f) | |

OD_ARG_NONNULL(1); | |

OD_WARN_UNUSED_RESULT int od_ec_decode_cdf_q15(od_ec_dec *dec, | |

const uint16_t *cdf, int nsyms) | |

OD_ARG_NONNULL(1) OD_ARG_NONNULL(2); | |

OD_WARN_UNUSED_RESULT uint32_t od_ec_dec_bits_(od_ec_dec *dec, unsigned ftb) | |

OD_ARG_NONNULL(1); | |

OD_WARN_UNUSED_RESULT int od_ec_dec_tell(const od_ec_dec *dec) | |

OD_ARG_NONNULL(1); | |

OD_WARN_UNUSED_RESULT uint32_t od_ec_dec_tell_frac(const od_ec_dec *dec) | |

OD_ARG_NONNULL(1); | |

#ifdef __cplusplus | |

} // extern "C" | |

#endif | |

#endif // AOM_AOM_DSP_ENTDEC_H_ |