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26abc3b5f2
Update our opus implementation to a prerelease of 1.1. This brings many performance and encoder improvements and we believe it is stable enough to switch. This import does not enable any of the new assembly optimizations. The imported code is https://git.xiph.org/opus.git master commit f2446c25c6519bae190152f7a579310b83dc43fd.
94 lines
3.3 KiB
C
94 lines
3.3 KiB
C
/* Copyright (c) 2001-2011 Timothy B. Terriberry
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*/
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/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
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OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "entcode.h"
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#include "arch.h"
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#if !defined(EC_CLZ)
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/*This is a fallback for systems where we don't know how to access
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a BSR or CLZ instruction (see ecintrin.h).
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If you are optimizing Opus on a new platform and it has a native CLZ or
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BZR (e.g. cell, MIPS, x86, etc) then making it available to Opus will be
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an easy performance win.*/
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int ec_ilog(opus_uint32 _v){
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/*On a Pentium M, this branchless version tested as the fastest on
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1,000,000,000 random 32-bit integers, edging out a similar version with
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branches, and a 256-entry LUT version.*/
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int ret;
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int m;
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ret=!!_v;
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m=!!(_v&0xFFFF0000)<<4;
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_v>>=m;
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ret|=m;
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m=!!(_v&0xFF00)<<3;
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_v>>=m;
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ret|=m;
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m=!!(_v&0xF0)<<2;
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_v>>=m;
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ret|=m;
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m=!!(_v&0xC)<<1;
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_v>>=m;
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ret|=m;
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ret+=!!(_v&0x2);
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return ret;
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}
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#endif
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opus_uint32 ec_tell_frac(ec_ctx *_this){
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opus_uint32 nbits;
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opus_uint32 r;
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int l;
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int i;
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/*To handle the non-integral number of bits still left in the encoder/decoder
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state, we compute the worst-case number of bits of val that must be
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encoded to ensure that the value is inside the range for any possible
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subsequent bits.
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The computation here is independent of val itself (the decoder does not
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even track that value), even though the real number of bits used after
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ec_enc_done() may be 1 smaller if rng is a power of two and the
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corresponding trailing bits of val are all zeros.
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If we did try to track that special case, then coding a value with a
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probability of 1/(1<<n) might sometimes appear to use more than n bits.
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This may help explain the surprising result that a newly initialized
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encoder or decoder claims to have used 1 bit.*/
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nbits=_this->nbits_total<<BITRES;
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l=EC_ILOG(_this->rng);
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r=_this->rng>>(l-16);
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for(i=BITRES;i-->0;){
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int b;
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r=r*r>>15;
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b=(int)(r>>16);
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l=l<<1|b;
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r>>=b;
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}
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return nbits-l;
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}
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