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81 lines
3 KiB
C
81 lines
3 KiB
C
/*Daala video codec
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Copyright (c) 2012 Daala project contributors. All rights reserved.
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Author: Timothy B. Terriberry
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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 are met:
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- Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS”
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.*/
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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 "kiss99.h"
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void kiss99_srand(kiss99_ctx *_this,const unsigned char *_data,int _ndata){
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int i;
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_this->z=362436069;
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_this->w=521288629;
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_this->jsr=123456789;
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_this->jcong=380116160;
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for(i=3;i<_ndata;i+=4){
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_this->z^=_data[i-3];
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_this->w^=_data[i-2];
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_this->jsr^=_data[i-1];
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_this->jcong^=_data[i];
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kiss99_rand(_this);
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}
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if(i-3<_ndata)_this->z^=_data[i-3];
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if(i-2<_ndata)_this->w^=_data[i-2];
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if(i-1<_ndata)_this->jsr^=_data[i-1];
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/*Fix any potential short cycles that show up.
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These are not too likely, given the way we initialize the state, but they
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are technically possible, so let us go ahead and eliminate that
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possibility.
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See Gregory G. Rose: "KISS: A Bit Too Simple", Cryptographic Communications
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No. 10, pp. 123---137, 2018.*/
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if(_this->z==0||_this->z==0x9068FFFF)_this->z++;
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if(_this->w==0||_this->w==0x464FFFFF)_this->w++;
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if(_this->jsr==0)_this->jsr++;
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}
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uint32_t kiss99_rand(kiss99_ctx *_this){
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uint32_t znew;
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uint32_t wnew;
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uint32_t mwc;
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uint32_t shr3;
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uint32_t cong;
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znew=36969*(_this->z&0xFFFF)+(_this->z>>16);
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wnew=18000*(_this->w&0xFFFF)+(_this->w>>16);
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mwc=(znew<<16)+wnew;
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/*We swap the 13 and 17 from the original 1999 algorithm to produce a single
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cycle of maximal length, matching KISS11.
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We are not actually using KISS11 because of the impractically large (16 MB)
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internal state of the full algorithm.*/
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shr3=_this->jsr^(_this->jsr<<13);
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shr3^=shr3>>17;
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shr3^=shr3<<5;
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cong=69069*_this->jcong+1234567;
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_this->z=znew;
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_this->w=wnew;
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_this->jsr=shr3;
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_this->jcong=cong;
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return (mwc^cong)+shr3;
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}
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