michael@0: /* Copyright (c) 2001-2011 Timothy B. Terriberry
michael@0:    Copyright (c) 2008-2009 Xiph.Org Foundation */
michael@0: /*
michael@0:    Redistribution and use in source and binary forms, with or without
michael@0:    modification, are permitted provided that the following conditions
michael@0:    are met:
michael@0: 
michael@0:    - Redistributions of source code must retain the above copyright
michael@0:    notice, this list of conditions and the following disclaimer.
michael@0: 
michael@0:    - Redistributions in binary form must reproduce the above copyright
michael@0:    notice, this list of conditions and the following disclaimer in the
michael@0:    documentation and/or other materials provided with the distribution.
michael@0: 
michael@0:    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0:    ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0:    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
michael@0:    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
michael@0:    OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
michael@0:    EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
michael@0:    PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
michael@0:    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
michael@0:    LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
michael@0:    NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
michael@0:    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0: */
michael@0: 
michael@0: #if !defined(_entdec_H)
michael@0: # define _entdec_H (1)
michael@0: # include <limits.h>
michael@0: # include "entcode.h"
michael@0: 
michael@0: /*Initializes the decoder.
michael@0:   _buf: The input buffer to use.
michael@0:   Return: 0 on success, or a negative value on error.*/
michael@0: void ec_dec_init(ec_dec *_this,unsigned char *_buf,opus_uint32 _storage);
michael@0: 
michael@0: /*Calculates the cumulative frequency for the next symbol.
michael@0:   This can then be fed into the probability model to determine what that
michael@0:    symbol is, and the additional frequency information required to advance to
michael@0:    the next symbol.
michael@0:   This function cannot be called more than once without a corresponding call to
michael@0:    ec_dec_update(), or decoding will not proceed correctly.
michael@0:   _ft: The total frequency of the symbols in the alphabet the next symbol was
michael@0:         encoded with.
michael@0:   Return: A cumulative frequency representing the encoded symbol.
michael@0:           If the cumulative frequency of all the symbols before the one that
michael@0:            was encoded was fl, and the cumulative frequency of all the symbols
michael@0:            up to and including the one encoded is fh, then the returned value
michael@0:            will fall in the range [fl,fh).*/
michael@0: unsigned ec_decode(ec_dec *_this,unsigned _ft);
michael@0: 
michael@0: /*Equivalent to ec_decode() with _ft==1<<_bits.*/
michael@0: unsigned ec_decode_bin(ec_dec *_this,unsigned _bits);
michael@0: 
michael@0: /*Advance the decoder past the next symbol using the frequency information the
michael@0:    symbol was encoded with.
michael@0:   Exactly one call to ec_decode() must have been made so that all necessary
michael@0:    intermediate calculations are performed.
michael@0:   _fl:  The cumulative frequency of all symbols that come before the symbol
michael@0:          decoded.
michael@0:   _fh:  The cumulative frequency of all symbols up to and including the symbol
michael@0:          decoded.
michael@0:         Together with _fl, this defines the range [_fl,_fh) in which the value
michael@0:          returned above must fall.
michael@0:   _ft:  The total frequency of the symbols in the alphabet the symbol decoded
michael@0:          was encoded in.
michael@0:         This must be the same as passed to the preceding call to ec_decode().*/
michael@0: void ec_dec_update(ec_dec *_this,unsigned _fl,unsigned _fh,unsigned _ft);
michael@0: 
michael@0: /* Decode a bit that has a 1/(1<<_logp) probability of being a one */
michael@0: int ec_dec_bit_logp(ec_dec *_this,unsigned _logp);
michael@0: 
michael@0: /*Decodes a symbol given an "inverse" CDF table.
michael@0:   No call to ec_dec_update() is necessary after this call.
michael@0:   _icdf: The "inverse" CDF, such that symbol s falls in the range
michael@0:           [s>0?ft-_icdf[s-1]:0,ft-_icdf[s]), where ft=1<<_ftb.
michael@0:          The values must be monotonically non-increasing, and the last value
michael@0:           must be 0.
michael@0:   _ftb: The number of bits of precision in the cumulative distribution.
michael@0:   Return: The decoded symbol s.*/
michael@0: int ec_dec_icdf(ec_dec *_this,const unsigned char *_icdf,unsigned _ftb);
michael@0: 
michael@0: /*Extracts a raw unsigned integer with a non-power-of-2 range from the stream.
michael@0:   The bits must have been encoded with ec_enc_uint().
michael@0:   No call to ec_dec_update() is necessary after this call.
michael@0:   _ft: The number of integers that can be decoded (one more than the max).
michael@0:        This must be at least one, and no more than 2**32-1.
michael@0:   Return: The decoded bits.*/
michael@0: opus_uint32 ec_dec_uint(ec_dec *_this,opus_uint32 _ft);
michael@0: 
michael@0: /*Extracts a sequence of raw bits from the stream.
michael@0:   The bits must have been encoded with ec_enc_bits().
michael@0:   No call to ec_dec_update() is necessary after this call.
michael@0:   _ftb: The number of bits to extract.
michael@0:         This must be between 0 and 25, inclusive.
michael@0:   Return: The decoded bits.*/
michael@0: opus_uint32 ec_dec_bits(ec_dec *_this,unsigned _ftb);
michael@0: 
michael@0: #endif