Initial community commit
This commit is contained in:
Jef
parent
537bcbc862
commit
fc06254474
16440 changed files with 4239995 additions and 2 deletions
245
Src/external_dependencies/openmpt-trunk/include/opus/celt/entdec.c
vendored
Normal file
245
Src/external_dependencies/openmpt-trunk/include/opus/celt/entdec.c
vendored
Normal file
|
|
@ -0,0 +1,245 @@
|
|||
/* 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.
|
||||
*/
|
||||
|
||||
#ifdef HAVE_CONFIG_H
|
||||
#include "config.h"
|
||||
#endif
|
||||
|
||||
#include <stddef.h>
|
||||
#include "os_support.h"
|
||||
#include "arch.h"
|
||||
#include "entdec.h"
|
||||
#include "mfrngcod.h"
|
||||
|
||||
/*A range decoder.
|
||||
This is an entropy decoder based upon \cite{Mar79}, which is itself a
|
||||
rediscovery of the FIFO arithmetic code introduced by \cite{Pas76}.
|
||||
It is very similar to arithmetic encoding, except that encoding is done with
|
||||
digits in any base, instead of with bits, and so it is faster when using
|
||||
larger bases (i.e.: a byte).
|
||||
The author claims an average waste of $\frac{1}{2}\log_b(2b)$ bits, where $b$
|
||||
is the base, longer than the theoretical optimum, but to my knowledge there
|
||||
is no published justification for this claim.
|
||||
This only seems true when using near-infinite precision arithmetic so that
|
||||
the process is carried out with no rounding errors.
|
||||
|
||||
An excellent description of implementation details is available at
|
||||
http://www.arturocampos.com/ac_range.html
|
||||
A recent work \cite{MNW98} which proposes several changes to arithmetic
|
||||
encoding for efficiency actually re-discovers many of the principles
|
||||
behind range encoding, and presents a good theoretical analysis of them.
|
||||
|
||||
End of stream is handled by writing out the smallest number of bits that
|
||||
ensures that the stream will be correctly decoded regardless of the value of
|
||||
any subsequent bits.
|
||||
ec_tell() can be used to determine how many bits were needed to decode
|
||||
all the symbols thus far; other data can be packed in the remaining bits of
|
||||
the input buffer.
|
||||
@PHDTHESIS{Pas76,
|
||||
author="Richard Clark Pasco",
|
||||
title="Source coding algorithms for fast data compression",
|
||||
school="Dept. of Electrical Engineering, Stanford University",
|
||||
address="Stanford, CA",
|
||||
month=May,
|
||||
year=1976
|
||||
}
|
||||
@INPROCEEDINGS{Mar79,
|
||||
author="Martin, G.N.N.",
|
||||
title="Range encoding: an algorithm for removing redundancy from a digitised
|
||||
message",
|
||||
booktitle="Video & Data Recording Conference",
|
||||
year=1979,
|
||||
address="Southampton",
|
||||
month=Jul
|
||||
}
|
||||
@ARTICLE{MNW98,
|
||||
author="Alistair Moffat and Radford Neal and Ian H. Witten",
|
||||
title="Arithmetic Coding Revisited",
|
||||
journal="{ACM} Transactions on Information Systems",
|
||||
year=1998,
|
||||
volume=16,
|
||||
number=3,
|
||||
pages="256--294",
|
||||
month=Jul,
|
||||
URL="http://www.stanford.edu/class/ee398a/handouts/papers/Moffat98ArithmCoding.pdf"
|
||||
}*/
|
||||
|
||||
static int ec_read_byte(ec_dec *_this){
|
||||
return _this->offs<_this->storage?_this->buf[_this->offs++]:0;
|
||||
}
|
||||
|
||||
static int ec_read_byte_from_end(ec_dec *_this){
|
||||
return _this->end_offs<_this->storage?
|
||||
_this->buf[_this->storage-++(_this->end_offs)]:0;
|
||||
}
|
||||
|
||||
/*Normalizes the contents of val and rng so that rng lies entirely in the
|
||||
high-order symbol.*/
|
||||
static void ec_dec_normalize(ec_dec *_this){
|
||||
/*If the range is too small, rescale it and input some bits.*/
|
||||
while(_this->rng<=EC_CODE_BOT){
|
||||
int sym;
|
||||
_this->nbits_total+=EC_SYM_BITS;
|
||||
_this->rng<<=EC_SYM_BITS;
|
||||
/*Use up the remaining bits from our last symbol.*/
|
||||
sym=_this->rem;
|
||||
/*Read the next value from the input.*/
|
||||
_this->rem=ec_read_byte(_this);
|
||||
/*Take the rest of the bits we need from this new symbol.*/
|
||||
sym=(sym<<EC_SYM_BITS|_this->rem)>>(EC_SYM_BITS-EC_CODE_EXTRA);
|
||||
/*And subtract them from val, capped to be less than EC_CODE_TOP.*/
|
||||
_this->val=((_this->val<<EC_SYM_BITS)+(EC_SYM_MAX&~sym))&(EC_CODE_TOP-1);
|
||||
}
|
||||
}
|
||||
|
||||
void ec_dec_init(ec_dec *_this,unsigned char *_buf,opus_uint32 _storage){
|
||||
_this->buf=_buf;
|
||||
_this->storage=_storage;
|
||||
_this->end_offs=0;
|
||||
_this->end_window=0;
|
||||
_this->nend_bits=0;
|
||||
/*This is the offset from which ec_tell() will subtract partial bits.
|
||||
The final value after the ec_dec_normalize() call will be the same as in
|
||||
the encoder, but we have to compensate for the bits that are added there.*/
|
||||
_this->nbits_total=EC_CODE_BITS+1
|
||||
-((EC_CODE_BITS-EC_CODE_EXTRA)/EC_SYM_BITS)*EC_SYM_BITS;
|
||||
_this->offs=0;
|
||||
_this->rng=1U<<EC_CODE_EXTRA;
|
||||
_this->rem=ec_read_byte(_this);
|
||||
_this->val=_this->rng-1-(_this->rem>>(EC_SYM_BITS-EC_CODE_EXTRA));
|
||||
_this->error=0;
|
||||
/*Normalize the interval.*/
|
||||
ec_dec_normalize(_this);
|
||||
}
|
||||
|
||||
unsigned ec_decode(ec_dec *_this,unsigned _ft){
|
||||
unsigned s;
|
||||
_this->ext=celt_udiv(_this->rng,_ft);
|
||||
s=(unsigned)(_this->val/_this->ext);
|
||||
return _ft-EC_MINI(s+1,_ft);
|
||||
}
|
||||
|
||||
unsigned ec_decode_bin(ec_dec *_this,unsigned _bits){
|
||||
unsigned s;
|
||||
_this->ext=_this->rng>>_bits;
|
||||
s=(unsigned)(_this->val/_this->ext);
|
||||
return (1U<<_bits)-EC_MINI(s+1U,1U<<_bits);
|
||||
}
|
||||
|
||||
void ec_dec_update(ec_dec *_this,unsigned _fl,unsigned _fh,unsigned _ft){
|
||||
opus_uint32 s;
|
||||
s=IMUL32(_this->ext,_ft-_fh);
|
||||
_this->val-=s;
|
||||
_this->rng=_fl>0?IMUL32(_this->ext,_fh-_fl):_this->rng-s;
|
||||
ec_dec_normalize(_this);
|
||||
}
|
||||
|
||||
/*The probability of having a "one" is 1/(1<<_logp).*/
|
||||
int ec_dec_bit_logp(ec_dec *_this,unsigned _logp){
|
||||
opus_uint32 r;
|
||||
opus_uint32 d;
|
||||
opus_uint32 s;
|
||||
int ret;
|
||||
r=_this->rng;
|
||||
d=_this->val;
|
||||
s=r>>_logp;
|
||||
ret=d<s;
|
||||
if(!ret)_this->val=d-s;
|
||||
_this->rng=ret?s:r-s;
|
||||
ec_dec_normalize(_this);
|
||||
return ret;
|
||||
}
|
||||
|
||||
int ec_dec_icdf(ec_dec *_this,const unsigned char *_icdf,unsigned _ftb){
|
||||
opus_uint32 r;
|
||||
opus_uint32 d;
|
||||
opus_uint32 s;
|
||||
opus_uint32 t;
|
||||
int ret;
|
||||
s=_this->rng;
|
||||
d=_this->val;
|
||||
r=s>>_ftb;
|
||||
ret=-1;
|
||||
do{
|
||||
t=s;
|
||||
s=IMUL32(r,_icdf[++ret]);
|
||||
}
|
||||
while(d<s);
|
||||
_this->val=d-s;
|
||||
_this->rng=t-s;
|
||||
ec_dec_normalize(_this);
|
||||
return ret;
|
||||
}
|
||||
|
||||
opus_uint32 ec_dec_uint(ec_dec *_this,opus_uint32 _ft){
|
||||
unsigned ft;
|
||||
unsigned s;
|
||||
int ftb;
|
||||
/*In order to optimize EC_ILOG(), it is undefined for the value 0.*/
|
||||
celt_assert(_ft>1);
|
||||
_ft--;
|
||||
ftb=EC_ILOG(_ft);
|
||||
if(ftb>EC_UINT_BITS){
|
||||
opus_uint32 t;
|
||||
ftb-=EC_UINT_BITS;
|
||||
ft=(unsigned)(_ft>>ftb)+1;
|
||||
s=ec_decode(_this,ft);
|
||||
ec_dec_update(_this,s,s+1,ft);
|
||||
t=(opus_uint32)s<<ftb|ec_dec_bits(_this,ftb);
|
||||
if(t<=_ft)return t;
|
||||
_this->error=1;
|
||||
return _ft;
|
||||
}
|
||||
else{
|
||||
_ft++;
|
||||
s=ec_decode(_this,(unsigned)_ft);
|
||||
ec_dec_update(_this,s,s+1,(unsigned)_ft);
|
||||
return s;
|
||||
}
|
||||
}
|
||||
|
||||
opus_uint32 ec_dec_bits(ec_dec *_this,unsigned _bits){
|
||||
ec_window window;
|
||||
int available;
|
||||
opus_uint32 ret;
|
||||
window=_this->end_window;
|
||||
available=_this->nend_bits;
|
||||
if((unsigned)available<_bits){
|
||||
do{
|
||||
window|=(ec_window)ec_read_byte_from_end(_this)<<available;
|
||||
available+=EC_SYM_BITS;
|
||||
}
|
||||
while(available<=EC_WINDOW_SIZE-EC_SYM_BITS);
|
||||
}
|
||||
ret=(opus_uint32)window&(((opus_uint32)1<<_bits)-1U);
|
||||
window>>=_bits;
|
||||
available-=_bits;
|
||||
_this->end_window=window;
|
||||
_this->nend_bits=available;
|
||||
_this->nbits_total+=_bits;
|
||||
return ret;
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue