cobalt / cobalt / b95ea55ccebda33f820d043e4b4dc85c10d7584d / . / third_party / opus / celt / entdec.h

/* Copyright (c) 2001-2011 Timothy B. Terriberry | |

Copyright (c) 2008-2009 Xiph.Org Foundation */ | |

/* | |

Redistribution and use in source and binary forms, with or without | |

modification, are permitted provided that the following conditions | |

are met: | |

- Redistributions of source code must retain the above copyright | |

notice, this list of conditions and the following disclaimer. | |

- Redistributions in binary form must reproduce the above copyright | |

notice, this list of conditions and the following disclaimer in the | |

documentation and/or other materials provided with the distribution. | |

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |

``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |

LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |

A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER | |

OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, | |

EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, | |

PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR | |

PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF | |

LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING | |

NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS | |

SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |

*/ | |

#if !defined(_entdec_H) | |

# define _entdec_H (1) | |

# include <limits.h> | |

# include "entcode.h" | |

/*Initializes the decoder. | |

_buf: The input buffer to use. | |

Return: 0 on success, or a negative value on error.*/ | |

void ec_dec_init(ec_dec *_this,unsigned char *_buf,opus_uint32 _storage); | |

/*Calculates the cumulative frequency for the next symbol. | |

This can then be fed into the probability model to determine what that | |

symbol is, and the additional frequency information required to advance to | |

the next symbol. | |

This function cannot be called more than once without a corresponding call to | |

ec_dec_update(), or decoding will not proceed correctly. | |

_ft: The total frequency of the symbols in the alphabet the next symbol was | |

encoded with. | |

Return: A cumulative frequency representing the encoded symbol. | |

If the cumulative frequency of all the symbols before the one that | |

was encoded was fl, and the cumulative frequency of all the symbols | |

up to and including the one encoded is fh, then the returned value | |

will fall in the range [fl,fh).*/ | |

unsigned ec_decode(ec_dec *_this,unsigned _ft); | |

/*Equivalent to ec_decode() with _ft==1<<_bits.*/ | |

unsigned ec_decode_bin(ec_dec *_this,unsigned _bits); | |

/*Advance the decoder past the next symbol using the frequency information the | |

symbol was encoded with. | |

Exactly one call to ec_decode() must have been made so that all necessary | |

intermediate calculations are performed. | |

_fl: The cumulative frequency of all symbols that come before the symbol | |

decoded. | |

_fh: The cumulative frequency of all symbols up to and including the symbol | |

decoded. | |

Together with _fl, this defines the range [_fl,_fh) in which the value | |

returned above must fall. | |

_ft: The total frequency of the symbols in the alphabet the symbol decoded | |

was encoded in. | |

This must be the same as passed to the preceding call to ec_decode().*/ | |

void ec_dec_update(ec_dec *_this,unsigned _fl,unsigned _fh,unsigned _ft); | |

/* Decode a bit that has a 1/(1<<_logp) probability of being a one */ | |

int ec_dec_bit_logp(ec_dec *_this,unsigned _logp); | |

/*Decodes a symbol given an "inverse" CDF table. | |

No call to ec_dec_update() is necessary after this call. | |

_icdf: The "inverse" CDF, such that symbol s falls in the range | |

[s>0?ft-_icdf[s-1]:0,ft-_icdf[s]), where ft=1<<_ftb. | |

The values must be monotonically non-increasing, and the last value | |

must be 0. | |

_ftb: The number of bits of precision in the cumulative distribution. | |

Return: The decoded symbol s.*/ | |

int ec_dec_icdf(ec_dec *_this,const unsigned char *_icdf,unsigned _ftb); | |

/*Extracts a raw unsigned integer with a non-power-of-2 range from the stream. | |

The bits must have been encoded with ec_enc_uint(). | |

No call to ec_dec_update() is necessary after this call. | |

_ft: The number of integers that can be decoded (one more than the max). | |

This must be at least 2, and no more than 2**32-1. | |

Return: The decoded bits.*/ | |

opus_uint32 ec_dec_uint(ec_dec *_this,opus_uint32 _ft); | |

/*Extracts a sequence of raw bits from the stream. | |

The bits must have been encoded with ec_enc_bits(). | |

No call to ec_dec_update() is necessary after this call. | |

_ftb: The number of bits to extract. | |

This must be between 0 and 25, inclusive. | |

Return: The decoded bits.*/ | |

opus_uint32 ec_dec_bits(ec_dec *_this,unsigned _ftb); | |

#endif |