299 lines
9.3 KiB
C
299 lines
9.3 KiB
C
|
/* 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 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(HAVE_CONFIG_H)
|
||
|
|
# include "config.h"
|
||
|
|
#endif
|
||
|
|
#include "os_support.h"
|
||
|
|
#include "arch.h"
|
||
|
|
#include "entenc.h"
|
||
|
|
#include "mfrngcod.h"
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
/*A range encoder.
|
||
|
|
See entdec.c and the references for implementation details \cite{Mar79,MNW98}.
|
||
|
|
|
||
|
|
@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/ee398/handouts/papers/Moffat98ArithmCoding.pdf"
|
||
|
|
}*/
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
static int ec_write_byte(ec_enc *_this,unsigned _value){
|
||
|
|
if(_this->offs+_this->end_offs>=_this->storage)return -1;
|
||
|
|
_this->buf[_this->offs++]=(unsigned char)_value;
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int ec_write_byte_at_end(ec_enc *_this,unsigned _value){
|
||
|
|
if(_this->offs+_this->end_offs>=_this->storage)return -1;
|
||
|
|
_this->buf[_this->storage-++(_this->end_offs)]=(unsigned char)_value;
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/*Outputs a symbol, with a carry bit.
|
||
|
|
If there is a potential to propagate a carry over several symbols, they are
|
||
|
|
buffered until it can be determined whether or not an actual carry will
|
||
|
|
occur.
|
||
|
|
If the counter for the buffered symbols overflows, then the stream becomes
|
||
|
|
undecodable.
|
||
|
|
This gives a theoretical limit of a few billion symbols in a single packet on
|
||
|
|
32-bit systems.
|
||
|
|
The alternative is to truncate the range in order to force a carry, but
|
||
|
|
requires similar carry tracking in the decoder, needlessly slowing it down.*/
|
||
|
|
static void ec_enc_carry_out(ec_enc *_this,int _c){
|
||
|
|
if(_c!=EC_SYM_MAX){
|
||
|
|
/*No further carry propagation possible, flush buffer.*/
|
||
|
|
int carry;
|
||
|
|
carry=_c>>EC_SYM_BITS;
|
||
|
|
/*Don't output a byte on the first write.
|
||
|
|
This compare should be taken care of by branch-prediction thereafter.*/
|
||
|
|
if(_this->rem>=0)_this->error|=ec_write_byte(_this,_this->rem+carry);
|
||
|
|
if(_this->ext>0){
|
||
|
|
unsigned sym;
|
||
|
|
sym=EC_SYM_MAX+carry&EC_SYM_MAX;
|
||
|
|
do _this->error|=ec_write_byte(_this,sym);
|
||
|
|
while(--(_this->ext)>0);
|
||
|
|
}
|
||
|
|
_this->rem=_c&EC_SYM_MAX;
|
||
|
|
}
|
||
|
|
else _this->ext++;
|
||
|
|
}
|
||
|
|
|
||
|
|
static void ec_enc_normalize(ec_enc *_this){
|
||
|
|
/*If the range is too small, output some bits and rescale it.*/
|
||
|
|
while(_this->rng<=EC_CODE_BOT){
|
||
|
|
ec_enc_carry_out(_this,(int)(_this->val>>EC_CODE_SHIFT));
|
||
|
|
/*Move the next-to-high-order symbol into the high-order position.*/
|
||
|
|
_this->val=_this->val<<EC_SYM_BITS&EC_CODE_TOP-1;
|
||
|
|
_this->rng<<=EC_SYM_BITS;
|
||
|
|
_this->nbits_total+=EC_SYM_BITS;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
void ec_enc_init(ec_enc *_this,unsigned char *_buf,celt_uint32 _size){
|
||
|
|
_this->buf=_buf;
|
||
|
|
_this->end_offs=0;
|
||
|
|
_this->end_window=0;
|
||
|
|
_this->nend_bits=0;
|
||
|
|
/*This is the offset from which ec_tell() will subtract partial bits.*/
|
||
|
|
_this->nbits_total=EC_CODE_BITS+1;
|
||
|
|
_this->offs=0;
|
||
|
|
_this->rng=EC_CODE_TOP;
|
||
|
|
_this->rem=-1;
|
||
|
|
_this->val=0;
|
||
|
|
_this->ext=0;
|
||
|
|
_this->storage=_size;
|
||
|
|
_this->error=0;
|
||
|
|
}
|
||
|
|
|
||
|
|
void ec_encode(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _ft){
|
||
|
|
celt_uint32 r;
|
||
|
|
r=_this->rng/_ft;
|
||
|
|
if(_fl>0){
|
||
|
|
_this->val+=_this->rng-IMUL32(r,(_ft-_fl));
|
||
|
|
_this->rng=IMUL32(r,(_fh-_fl));
|
||
|
|
}
|
||
|
|
else _this->rng-=IMUL32(r,(_ft-_fh));
|
||
|
|
ec_enc_normalize(_this);
|
||
|
|
}
|
||
|
|
|
||
|
|
void ec_encode_bin(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _bits){
|
||
|
|
celt_uint32 r;
|
||
|
|
r=_this->rng>>_bits;
|
||
|
|
if(_fl>0){
|
||
|
|
_this->val+=_this->rng-IMUL32(r,((1<<_bits)-_fl));
|
||
|
|
_this->rng=IMUL32(r,(_fh-_fl));
|
||
|
|
}
|
||
|
|
else _this->rng-=IMUL32(r,((1<<_bits)-_fh));
|
||
|
|
ec_enc_normalize(_this);
|
||
|
|
}
|
||
|
|
|
||
|
|
/*The probability of having a "one" is 1/(1<<_logp).*/
|
||
|
|
void ec_enc_bit_logp(ec_enc *_this,int _val,unsigned _logp){
|
||
|
|
celt_uint32 r;
|
||
|
|
celt_uint32 s;
|
||
|
|
celt_uint32 l;
|
||
|
|
r=_this->rng;
|
||
|
|
l=_this->val;
|
||
|
|
s=r>>_logp;
|
||
|
|
r-=s;
|
||
|
|
if(_val)_this->val=l+r;
|
||
|
|
_this->rng=_val?s:r;
|
||
|
|
ec_enc_normalize(_this);
|
||
|
|
}
|
||
|
|
|
||
|
|
void ec_enc_icdf(ec_enc *_this,int _s,const unsigned char *_icdf,unsigned _ftb){
|
||
|
|
celt_uint32 r;
|
||
|
|
r=_this->rng>>_ftb;
|
||
|
|
if(_s>0){
|
||
|
|
_this->val+=_this->rng-IMUL32(r,_icdf[_s-1]);
|
||
|
|
_this->rng=IMUL32(r,_icdf[_s-1]-_icdf[_s]);
|
||
|
|
}
|
||
|
|
else _this->rng-=IMUL32(r,_icdf[_s]);
|
||
|
|
ec_enc_normalize(_this);
|
||
|
|
}
|
||
|
|
|
||
|
|
void ec_enc_uint(ec_enc *_this,celt_uint32 _fl,celt_uint32 _ft){
|
||
|
|
unsigned ft;
|
||
|
|
unsigned fl;
|
||
|
|
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){
|
||
|
|
ftb-=EC_UINT_BITS;
|
||
|
|
ft=(_ft>>ftb)+1;
|
||
|
|
fl=(unsigned)(_fl>>ftb);
|
||
|
|
ec_encode(_this,fl,fl+1,ft);
|
||
|
|
ec_enc_bits(_this,_fl&((celt_uint32)1<<ftb)-1,ftb);
|
||
|
|
}
|
||
|
|
else ec_encode(_this,_fl,_fl+1,_ft+1);
|
||
|
|
}
|
||
|
|
|
||
|
|
void ec_enc_bits(ec_enc *_this,celt_uint32 _fl,unsigned _bits){
|
||
|
|
ec_window window;
|
||
|
|
int used;
|
||
|
|
window=_this->end_window;
|
||
|
|
used=_this->nend_bits;
|
||
|
|
if(used+_bits>EC_WINDOW_SIZE){
|
||
|
|
do{
|
||
|
|
_this->error|=ec_write_byte_at_end(_this,(unsigned)window&EC_SYM_MAX);
|
||
|
|
window>>=EC_SYM_BITS;
|
||
|
|
used-=EC_SYM_BITS;
|
||
|
|
}
|
||
|
|
while(used>=EC_SYM_BITS);
|
||
|
|
}
|
||
|
|
window|=(ec_window)_fl<<used;
|
||
|
|
used+=_bits;
|
||
|
|
_this->end_window=window;
|
||
|
|
_this->nend_bits=used;
|
||
|
|
_this->nbits_total+=_bits;
|
||
|
|
}
|
||
|
|
|
||
|
|
void ec_enc_patch_initial_bits(ec_enc *_this,unsigned _val,unsigned _nbits){
|
||
|
|
int shift;
|
||
|
|
unsigned mask;
|
||
|
|
celt_assert(_nbits<=EC_SYM_BITS);
|
||
|
|
shift=EC_SYM_BITS-_nbits;
|
||
|
|
mask=(1<<_nbits)-1<<shift;
|
||
|
|
if(_this->offs>0){
|
||
|
|
/*The first byte has been finalized.*/
|
||
|
|
_this->buf[0]=(unsigned char)(_this->buf[0]&~mask|_val<<shift);
|
||
|
|
}
|
||
|
|
else if(_this->rem>=0){
|
||
|
|
/*The first byte is still awaiting carry propagation.*/
|
||
|
|
_this->rem=_this->rem&~mask|_val<<shift;
|
||
|
|
}
|
||
|
|
else if(_this->rng<=EC_CODE_TOP>>shift){
|
||
|
|
/*The renormalization loop has never been run.*/
|
||
|
|
_this->val=_this->val&~((celt_uint32)mask<<EC_CODE_SHIFT)|
|
||
|
|
(celt_uint32)_val<<EC_CODE_SHIFT+shift;
|
||
|
|
}
|
||
|
|
/*The encoder hasn't even encoded _nbits of data yet.*/
|
||
|
|
else _this->error=-1;
|
||
|
|
}
|
||
|
|
|
||
|
|
void ec_enc_shrink(ec_enc *_this,celt_uint32 _size){
|
||
|
|
celt_assert(_this->offs+_this->end_offs<=_size);
|
||
|
|
CELT_MOVE(_this->buf+_size-_this->end_offs,
|
||
|
|
_this->buf+_this->storage-_this->end_offs,_this->end_offs);
|
||
|
|
_this->storage=_size;
|
||
|
|
}
|
||
|
|
|
||
|
|
void ec_enc_done(ec_enc *_this){
|
||
|
|
ec_window window;
|
||
|
|
int used;
|
||
|
|
celt_uint32 msk;
|
||
|
|
celt_uint32 end;
|
||
|
|
int l;
|
||
|
|
/*We output the minimum number of bits that ensures that the symbols encoded
|
||
|
|
thus far will be decoded correctly regardless of the bits that follow.*/
|
||
|
|
l=EC_CODE_BITS-EC_ILOG(_this->rng);
|
||
|
|
msk=EC_CODE_TOP-1>>l;
|
||
|
|
end=_this->val+msk&~msk;
|
||
|
|
if((end|msk)>=_this->val+_this->rng){
|
||
|
|
l++;
|
||
|
|
msk>>=1;
|
||
|
|
end=_this->val+msk&~msk;
|
||
|
|
}
|
||
|
|
while(l>0){
|
||
|
|
ec_enc_carry_out(_this,(int)(end>>EC_CODE_SHIFT));
|
||
|
|
end=end<<EC_SYM_BITS&EC_CODE_TOP-1;
|
||
|
|
l-=EC_SYM_BITS;
|
||
|
|
}
|
||
|
|
/*If we have a buffered byte flush it into the output buffer.*/
|
||
|
|
if(_this->rem>=0||_this->ext>0)ec_enc_carry_out(_this,0);
|
||
|
|
/*If we have buffered extra bits, flush them as well.*/
|
||
|
|
window=_this->end_window;
|
||
|
|
used=_this->nend_bits;
|
||
|
|
while(used>=EC_SYM_BITS){
|
||
|
|
_this->error|=ec_write_byte_at_end(_this,(unsigned)window&EC_SYM_MAX);
|
||
|
|
window>>=EC_SYM_BITS;
|
||
|
|
used-=EC_SYM_BITS;
|
||
|
|
}
|
||
|
|
/*Clear any excess space and add any remaining extra bits to the last byte.*/
|
||
|
|
if(!_this->error){
|
||
|
|
CELT_MEMSET(_this->buf+_this->offs,0,
|
||
|
|
_this->storage-_this->offs-_this->end_offs);
|
||
|
|
if(used>0){
|
||
|
|
/*If there's no range coder data at all, give up.*/
|
||
|
|
if(_this->end_offs>=_this->storage)_this->error=-1;
|
||
|
|
else{
|
||
|
|
l=-l;
|
||
|
|
/*If we've busted, don't add too many extra bits to the last byte; it
|
||
|
|
would corrupt the range coder data, and that's more important.*/
|
||
|
|
if(_this->offs+_this->end_offs>=_this->storage&&l<used){
|
||
|
|
window&=(1<<l)-1;
|
||
|
|
_this->error=-1;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
_this->buf[_this->storage-_this->end_offs-1]|=(unsigned char)window;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|