Adding libopus source and Android.mk
Adding libopus source code and Android.mk. The source is based
on latest stable release libopus 1.1.
Change-Id: I0841894ee0766829e6d0e1b8379e6f6f87b0852f
diff --git a/celt/entdec.c b/celt/entdec.c
new file mode 100644
index 0000000..3c26468
--- /dev/null
+++ b/celt/entdec.c
@@ -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=_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;
+}