133 lines
4.7 KiB
C
133 lines
4.7 KiB
C
/* Copyright (c) 2001-2011 Timothy B. Terriberry
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Copyright (c) 2008-2009 Xiph.Org Foundation */
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/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "celt_types.h"
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#if !defined(_entcode_H)
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# define _entcode_H (1)
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# include <limits.h>
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# include <stddef.h>
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# include "ecintrin.h"
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typedef celt_int32 ec_int32;
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typedef celt_uint32 ec_uint32;
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typedef celt_uint32 ec_window;
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typedef struct ec_ctx ec_ctx;
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typedef struct ec_ctx ec_enc;
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typedef struct ec_ctx ec_dec;
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/*OPT: This must be at least 32 bits, but if you have fast arithmetic on a
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larger type, you can speed up the decoder by using it for ec_window.*/
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# define EC_WINDOW_SIZE ((int)sizeof(ec_window)*CHAR_BIT)
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/*The number of bits to use for the range-coded part of unsigned integers.*/
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# define EC_UINT_BITS (8)
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/*The resolution of fractional-precision bit usage measurements, i.e.,
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3 => 1/8th bits.*/
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# define BITRES 3
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/*The entropy encoder/decoder context.
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We use the same structure for both, so that common functions like ec_tell()
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can be used on either one.*/
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struct ec_ctx{
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/*Buffered input/output.*/
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unsigned char *buf;
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/*The size of the buffer.*/
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ec_uint32 storage;
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/*The offset at which the last byte containing raw bits was read/written.*/
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ec_uint32 end_offs;
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/*Bits that will be read from/written at the end.*/
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ec_window end_window;
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/*Number of valid bits in end_window.*/
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int nend_bits;
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/*The total number of whole bits read/written.
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This does not include partial bits currently in the range coder.*/
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int nbits_total;
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/*The offset at which the next range coder byte will be read/written.*/
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ec_uint32 offs;
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/*The number of values in the current range.*/
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ec_uint32 rng;
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/*In the decoder: the difference between the top of the current range and
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the input value, minus one.
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In the encoder: the low end of the current range.*/
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ec_uint32 val;
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/*In the decoder: the saved normalization factor from ec_decode().
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In the encoder: the number of oustanding carry propagating symbols.*/
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ec_uint32 ext;
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/*A buffered input/output symbol, awaiting carry propagation.*/
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int rem;
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/*Nonzero if an error occurred.*/
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int error;
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};
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/*Shared functions.*/
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static inline void ec_reset(ec_ctx *_this){
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_this->offs=_this->end_offs=0;
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}
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static inline ec_uint32 ec_range_bytes(ec_ctx *_this){
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return _this->offs;
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}
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static inline unsigned char *ec_get_buffer(ec_ctx *_this){
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return _this->buf;
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}
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static inline int ec_get_error(ec_ctx *_this){
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return _this->error;
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}
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/*Returns the number of bits "used" by the encoded or decoded symbols so far.
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This same number can be computed in either the encoder or the decoder, and is
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suitable for making coding decisions.
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Return: The number of bits.
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This will always be slightly larger than the exact value (e.g., all
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rounding error is in the positive direction).*/
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static inline int ec_tell(ec_ctx *_this){
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return _this->nbits_total-EC_ILOG(_this->rng);
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}
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/*Returns the number of bits "used" by the encoded or decoded symbols so far.
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This same number can be computed in either the encoder or the decoder, and is
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suitable for making coding decisions.
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Return: The number of bits scaled by 2**BITRES.
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This will always be slightly larger than the exact value (e.g., all
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rounding error is in the positive direction).*/
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ec_uint32 ec_tell_frac(ec_ctx *_this);
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int ec_ilog(ec_uint32 _v);
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#endif
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