1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/celt/entcode.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,93 @@
1.4 +/* Copyright (c) 2001-2011 Timothy B. Terriberry
1.5 +*/
1.6 +/*
1.7 + Redistribution and use in source and binary forms, with or without
1.8 + modification, are permitted provided that the following conditions
1.9 + are met:
1.10 +
1.11 + - Redistributions of source code must retain the above copyright
1.12 + notice, this list of conditions and the following disclaimer.
1.13 +
1.14 + - Redistributions in binary form must reproduce the above copyright
1.15 + notice, this list of conditions and the following disclaimer in the
1.16 + documentation and/or other materials provided with the distribution.
1.17 +
1.18 + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
1.19 + ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
1.20 + LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
1.21 + A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
1.22 + OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
1.23 + EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
1.24 + PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
1.25 + PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
1.26 + LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
1.27 + NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
1.28 + SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.29 +*/
1.30 +
1.31 +#ifdef HAVE_CONFIG_H
1.32 +#include "config.h"
1.33 +#endif
1.34 +
1.35 +#include "entcode.h"
1.36 +#include "arch.h"
1.37 +
1.38 +#if !defined(EC_CLZ)
1.39 +/*This is a fallback for systems where we don't know how to access
1.40 + a BSR or CLZ instruction (see ecintrin.h).
1.41 + If you are optimizing Opus on a new platform and it has a native CLZ or
1.42 + BZR (e.g. cell, MIPS, x86, etc) then making it available to Opus will be
1.43 + an easy performance win.*/
1.44 +int ec_ilog(opus_uint32 _v){
1.45 + /*On a Pentium M, this branchless version tested as the fastest on
1.46 + 1,000,000,000 random 32-bit integers, edging out a similar version with
1.47 + branches, and a 256-entry LUT version.*/
1.48 + int ret;
1.49 + int m;
1.50 + ret=!!_v;
1.51 + m=!!(_v&0xFFFF0000)<<4;
1.52 + _v>>=m;
1.53 + ret|=m;
1.54 + m=!!(_v&0xFF00)<<3;
1.55 + _v>>=m;
1.56 + ret|=m;
1.57 + m=!!(_v&0xF0)<<2;
1.58 + _v>>=m;
1.59 + ret|=m;
1.60 + m=!!(_v&0xC)<<1;
1.61 + _v>>=m;
1.62 + ret|=m;
1.63 + ret+=!!(_v&0x2);
1.64 + return ret;
1.65 +}
1.66 +#endif
1.67 +
1.68 +opus_uint32 ec_tell_frac(ec_ctx *_this){
1.69 + opus_uint32 nbits;
1.70 + opus_uint32 r;
1.71 + int l;
1.72 + int i;
1.73 + /*To handle the non-integral number of bits still left in the encoder/decoder
1.74 + state, we compute the worst-case number of bits of val that must be
1.75 + encoded to ensure that the value is inside the range for any possible
1.76 + subsequent bits.
1.77 + The computation here is independent of val itself (the decoder does not
1.78 + even track that value), even though the real number of bits used after
1.79 + ec_enc_done() may be 1 smaller if rng is a power of two and the
1.80 + corresponding trailing bits of val are all zeros.
1.81 + If we did try to track that special case, then coding a value with a
1.82 + probability of 1/(1<<n) might sometimes appear to use more than n bits.
1.83 + This may help explain the surprising result that a newly initialized
1.84 + encoder or decoder claims to have used 1 bit.*/
1.85 + nbits=_this->nbits_total<<BITRES;
1.86 + l=EC_ILOG(_this->rng);
1.87 + r=_this->rng>>(l-16);
1.88 + for(i=BITRES;i-->0;){
1.89 + int b;
1.90 + r=r*r>>15;
1.91 + b=(int)(r>>16);
1.92 + l=l<<1|b;
1.93 + r>>=b;
1.94 + }
1.95 + return nbits-l;
1.96 +}
