ref: 7627b9f660cf51005a61e187307da29de644386e
dir: /libcelt/entenc.h/
/* Copyright (c) 2001-2008 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.
- Neither the name of the Xiph.org Foundation nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
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 FOUNDATION 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(_entenc_H)
# define _entenc_H (1)
# include <stddef.h>
# include "entcode.h"
typedef struct ec_enc ec_enc;
/*The entropy encoder.*/
struct ec_enc{
/*Buffered output.*/
ec_byte_buffer *buf;
/*A buffered output symbol, awaiting carry propagation.*/
int rem;
/*Number of extra carry propagating symbols.*/
size_t ext;
/*The number of values in the current range.*/
ec_uint32 rng;
/*The low end of the current range (inclusive).*/
ec_uint32 low;
/*Byte that will be written at the end*/
unsigned char end_byte;
/*Number of valid bits in end_byte*/
int end_bits_left;
int nb_end_bits;
/*Nonzero if an error occurred*/
int error;
};
/*Initializes the encoder.
_buf: The buffer to store output bytes in.
This must have already been initialized for writing and reset.*/
void ec_enc_init(ec_enc *_this,ec_byte_buffer *_buf);
/*Encodes a symbol given its frequency information.
The frequency information must be discernable by the decoder, assuming it
has read only the previous symbols from the stream.
It is allowable to change the frequency information, or even the entire
source alphabet, so long as the decoder can tell from the context of the
previously encoded information that it is supposed to do so as well.
_fl: The cumulative frequency of all symbols that come before the one to be
encoded.
_fh: The cumulative frequency of all symbols up to and including the one to
be encoded.
Together with _fl, this defines the range [_fl,_fh) in which the
decoded value will fall.
_ft: The sum of the frequencies of all the symbols*/
void ec_encode(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _ft);
void ec_encode_bin(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _bits);
/*Encodes a sequence of raw bits in the stream.
_fl: The bits to encode.
_ftb: The number of bits to encode.
This must be at least one, and no more than 32.*/
void ec_enc_bits(ec_enc *_this,ec_uint32 _fl,unsigned _ftb);
/*Encodes a raw unsigned integer in the stream.
_fl: The integer to encode.
_ft: The number of integers that can be encoded (one more than the max).
This must be at least one, and no more than 2**32-1.*/
void ec_enc_uint(ec_enc *_this,ec_uint32 _fl,ec_uint32 _ft);
/* Encode a bit that has a _prob/65536 probability of being a one */
void ec_enc_bit_prob(ec_enc *_this,int val,unsigned _prob);
/*Returns the number of bits "used" by the encoded symbols so far.
This same number can be computed by the decoder, and is suitable for making
coding decisions.
_b: The number of extra bits of precision to include.
At most 16 will be accurate.
Return: The number of bits scaled by 2**_b.
This will always be slightly larger than the exact value (e.g., all
rounding error is in the positive direction).*/
ec_uint32 ec_enc_tell(ec_enc *_this,int _b);
/*Indicates that there are no more symbols to encode.
All reamining output bytes are flushed to the output buffer.
ec_enc_init() must be called before the encoder can be used again.*/
void ec_enc_done(ec_enc *_this);
/*Returns a nonzero value if any error has been detected during encoding*/
int ec_enc_get_error(ec_enc *_this);
#endif