rockbox/lib/rbcodec/codecs/libopus/celt/entcode.c
Frederik M J Vestre 1b8e3801b2 Initial opus codec support
Synchronised with opus repo on github (https://github.com/freqmod/rockbox-opus)

Status:
* Seeking ported from speex, but fails on some cases (e.g. seek to granule 0)
* ReplayGain parsing needs to be reworked, we do vorbis-style replaygain now.
  http://wiki.xiph.org/OggOpus#Comment_Header explicitly forbids these in
  favour of R128_TRACK_GAIN tag.
* No optimisation yet, source files still nearly identical to opus upstream
* Multi-stream opus files may not be parsed correctly

Change-Id: Ia66f1027dc1d288083e3c57b2816700078376f9a
Reviewed-on: http://gerrit.rockbox.org/300
Reviewed-by: Bertrik Sikken <bertrik@sikken.nl>
Tested-by: Bertrik Sikken <bertrik@sikken.nl>
2012-09-20 20:47:44 +02:00

88 lines
3 KiB
C

/* Copyright (c) 2001-2011 Timothy B. Terriberry
*/
/*
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 "opus_config.h"
#endif
#include "entcode.h"
#include "arch.h"
#if !defined(EC_CLZ)
int ec_ilog(opus_uint32 _v){
/*On a Pentium M, this branchless version tested as the fastest on
1,000,000,000 random 32-bit integers, edging out a similar version with
branches, and a 256-entry LUT version.*/
int ret;
int m;
ret=!!_v;
m=!!(_v&0xFFFF0000)<<4;
_v>>=m;
ret|=m;
m=!!(_v&0xFF00)<<3;
_v>>=m;
ret|=m;
m=!!(_v&0xF0)<<2;
_v>>=m;
ret|=m;
m=!!(_v&0xC)<<1;
_v>>=m;
ret|=m;
ret+=!!(_v&0x2);
return ret;
}
#endif
opus_uint32 ec_tell_frac(ec_ctx *_this){
opus_uint32 nbits;
opus_uint32 r;
int l;
int i;
/*To handle the non-integral number of bits still left in the encoder/decoder
state, we compute the worst-case number of bits of val that must be
encoded to ensure that the value is inside the range for any possible
subsequent bits.
The computation here is independent of val itself (the decoder does not
even track that value), even though the real number of bits used after
ec_enc_done() may be 1 smaller if rng is a power of two and the
corresponding trailing bits of val are all zeros.
If we did try to track that special case, then coding a value with a
probability of 1/(1<<n) might sometimes appear to use more than n bits.
This may help explain the surprising result that a newly initialized
encoder or decoder claims to have used 1 bit.*/
nbits=_this->nbits_total<<BITRES;
l=EC_ILOG(_this->rng);
r=_this->rng>>(l-16);
for(i=BITRES;i-->0;){
int b;
r=r*r>>15;
b=(int)(r>>16);
l=l<<1|b;
r>>=b;
}
return nbits-l;
}