653 lines
14 KiB
C++
653 lines
14 KiB
C++
/*
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LA: linear algebra C++ interface library
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Copyright (C) 2008-2023 Jiri Pittner <jiri.pittner@jh-inst.cas.cz> or <jiri@pittnerovi.com>
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "bitvector.h"
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#include <unistd.h>
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#include "numbers.h"
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namespace LA {
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//inefficient I/O operators
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std::ostream & operator<<(std::ostream &s, const bitvector &x)
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{
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for(unsigned int i=0; i<x.size(); ++i) s<< x[i];
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return s;
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}
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std::istream & operator>>(std::istream &s, bitvector &x)
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{
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std::string str;
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s >> str;
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x.resize(str.size());
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for(unsigned int i=0; i<x.size(); ++i) {x.assign(i,str[i]!='0');}
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return s;
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}
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void bitvector::zero_padding() const
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{
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if(!modulo) return;
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bitvector *p = const_cast<bitvector *>(this);
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p->v[nn-1] &= (1ULL<<modulo)-1;
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}
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bitvector& bitvector::operator++()
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{
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copyonwrite();
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zero_padding();
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int i=0;
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while(i<nn) if(++v[i++]) break;
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return *this;
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}
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bitvector& bitvector::operator--()
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{
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copyonwrite();
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zero_padding();
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int i=0;
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while(i<nn) if(v[i++]--) break;
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return *this;
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}
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//implemented so that vectors of different length are considered different automatically
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bool bitvector::operator!=(const bitvector &rhs) const
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{
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if(nn==rhs.nn && modulo==rhs.modulo && v==rhs.v) return false;
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zero_padding();
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rhs.zero_padding();
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int minnn=nn; if(rhs.nn<minnn) minnn=rhs.nn;
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int maxnn=nn; if(rhs.nn>maxnn) maxnn=rhs.nn;
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if(memcmp(v,rhs.v,minnn*sizeof(bitvector_block))) return true;
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if(minnn==maxnn) return false;
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if(nn==minnn) {for(int i=minnn; i<maxnn; ++i) if(rhs.v[i]) return true;}
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if(rhs.nn==minnn){for(int i=minnn; i<maxnn; ++i) if(v[i]) return true;}
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return false;
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}
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bool bitvector::operator>(const bitvector &rhs) const
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{
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if(nn!=rhs.nn || modulo!=rhs.modulo) laerror("at the moment only bitvectors of the same length comparable");
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if(v==rhs.v) return 0;
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if(!modulo) return memcmp(v,rhs.v,nn*sizeof(bitvector_block)>0);
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int r;
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if((r=memcmp(v,rhs.v,(nn-1)*sizeof(bitvector_block)))) return r>0;
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bitvector_block a=v[nn-1];
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bitvector_block b=rhs.v[nn-1];
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//zero out the irrelevant bits
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bitvector_block mask= ~((bitvector_block)0);
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mask <<=modulo;
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mask = ~mask;
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a&=mask; b&=mask;
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return a>b;
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}
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bool bitvector::operator<(const bitvector &rhs) const
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{
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if(nn!=rhs.nn || modulo!=rhs.modulo) laerror("at the moment only bitvectors of the same length comparable");
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if(v==rhs.v) return 0;
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if(!modulo) return memcmp(v,rhs.v,nn*sizeof(bitvector_block)<0);
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int r;
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if((r=memcmp(v,rhs.v,(nn-1)*sizeof(bitvector_block)))) return r<0;
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bitvector_block a=v[nn-1];
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bitvector_block b=rhs.v[nn-1];
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//zero out the irrelevant bits
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bitvector_block mask= ~((bitvector_block)0);
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mask <<=modulo;
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mask = ~mask;
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a&=mask; b&=mask;
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return a<b;
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}
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bitvector bitvector::operator~() const
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{
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bitvector r((*this).size());
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for(int i=0; i<nn; ++i) r.v[i] = ~v[i];
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r.zero_padding();
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return r;
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}
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bitvector& bitvector::operator&=(const bitvector &rhs)
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{
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if(size()<rhs.size()) resize(rhs.size(),true);
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copyonwrite();
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for(int i=0; i<nn; ++i) v[i] &= (i>=rhs.nn? 0 : rhs.v[i]);
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return *this;
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}
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bitvector& bitvector::operator|=(const bitvector &rhs)
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{
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if(size()<rhs.size()) resize(rhs.size(),true);
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copyonwrite();
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for(int i=0; i<nn && i<rhs.nn; ++i) v[i] |= rhs.v[i];
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return *this;
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}
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bitvector& bitvector::operator^=(const bitvector &rhs)
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{
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if(size()<rhs.size()) resize(rhs.size(),true);
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copyonwrite();
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for(int i=0; i<nn && i<rhs.nn; ++i) v[i] ^= rhs.v[i];
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return *this;
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}
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/*number of ones in a binary number, from "Hacker's delight" book*/
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#ifdef LONG_IS_32
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static unsigned int word_popul(unsigned long x)
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{
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x -= ((x>>1)&0x55555555);
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x = (x&0x33333333) + ((x>>2)&0x33333333);
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x=(x + (x>>4))&0x0f0f0f0f;
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x+= (x>>8);
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x+= (x>>16);
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return x&0x3f;
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}
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#else
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//@@@@ use an efficient trick too
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static unsigned int word_popul(unsigned long x)
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{
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unsigned int s=0;
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for(int i=0; i<64; ++i)
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{
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if(x&1) ++s;
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x>>=1;
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}
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return s;
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}
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#endif
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bitvector& bitvector::operator>>=(unsigned int i)
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{
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if(i==0) return *this;
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copyonwrite();
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unsigned int imod = i%blockbits;
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unsigned int ishift = i/blockbits;
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for(int dest=0; dest<nn; ++dest)
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{
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int src=dest+ishift;
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if(src>=nn) v[dest]=0;
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else
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{
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v[dest] = v[src]>>imod;
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if(imod && (src+1<nn)) v[dest] |= (v[src+1]&((1ULL<<imod)-1)) <<(blockbits-imod);
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}
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}
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return *this;
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}
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bitvector& bitvector::leftshift(unsigned int i, bool autoresize)
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{
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if(i==0) return *this;
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copyonwrite();
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unsigned int imod = i%blockbits;
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unsigned int ishift = i/blockbits;
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if(autoresize) resize(size()+i,true);
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for(int dest=nn-1; dest>=0; --dest)
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{
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int src=dest-ishift;
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if(src<0) v[dest]=0;
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else
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{
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v[dest] = v[src]<<imod;
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if(imod && (src-1>=0)) v[dest] |= (v[src-1]& (((1ULL<<imod)-1) <<(blockbits-imod)))>>(blockbits-imod);
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}
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}
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return *this;
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}
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void bitvector::randomize()
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{
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copyonwrite();
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for(int i=0; i<nn; ++i) v[i]=RANDINT64();
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zero_padding();
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}
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unsigned int bitvector::population(const unsigned int before) const
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{
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if(before) laerror("before parameter in population() not implemented yet");
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int i;
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unsigned int s=0;
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for(i=0; i<nn-1; ++i) s+=word_popul(v[i]);
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bitvector_block a=v[nn-1];
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if(modulo)
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{
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bitvector_block mask= ~((bitvector_block)0);
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mask <<=modulo;
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a &= ~mask;
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}
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return s+word_popul(a);
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}
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unsigned int bitvector::bitdiff(const bitvector &y) const
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{
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if(nn!=y.nn) laerror("incompatible size in bitdifference");
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unsigned int s=0;
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for(int i=0; i<nn-1; ++i) s+=word_popul(v[i]^y.v[i]);
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bitvector_block a=v[nn-1]^y.v[nn-1];
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if(modulo)
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{
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bitvector_block mask= ~((bitvector_block)0);
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mask <<=modulo;
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a &= ~mask;
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}
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return s+word_popul(a);
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}
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static unsigned int nlz64(uint64_t x0)
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{
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int64_t x=x0;
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uint64_t y;
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unsigned int n;
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n=0;
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y=x;
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L: if ( x<0) return n;
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if(y==0) return 64-n;
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++n;
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x<<=1;
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y>>=1;
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goto L;
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}
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static unsigned int ntz64(uint64_t x)
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{
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unsigned int n;
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if(x==0) return 64;
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n=1;
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if((x&0xffffffff)==0) {n+=32; x>>=32;}
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if((x&0xffff)==0) {n+=16; x>>=16;}
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if((x&0xff)==0) {n+=8; x>>=8;}
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if((x&0xf)==0) {n+=4; x>>=4;}
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if((x&0x3)==0) {n+=2; x>>=2;}
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return n-(x&1);
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}
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unsigned int bitvector::nlz() const
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{
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int leadblock=nn-1;
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unsigned int n=0;
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while(leadblock>0 && v[leadblock] == 0)
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{
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--leadblock;
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n+=blockbits;
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}
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n+= nlz64(v[leadblock]);
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if(modulo) n-= blockbits-modulo;
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return n;
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}
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unsigned int bitvector::ntz() const
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{
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int tailblock=0;
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unsigned int n=0;
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if(iszero()) return size();
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while(tailblock<nn-1 && v[tailblock] == 0)
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{
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++tailblock;
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n+=blockbits;
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}
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n+= ntz64(v[tailblock]);
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return n;
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}
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//NOTE: naive algorithm, just for testing
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//does not perform modulo irreducible polynomial, is NOT GF(2^n) multiplication
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bitvector bitvector::multiply(const bitvector &rhs, bool autoresize) const
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{
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int maxsize=size(); if(rhs.size()>maxsize) maxsize=rhs.size();
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bitvector r(autoresize?size()+rhs.size():maxsize);
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r.clear();
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bitvector tmp(rhs);
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if(autoresize) tmp.resize(size()+rhs.size(),true);
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for(int i=0; i<=degree(); ++i)
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{
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if((*this)[i]) r+= tmp;
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tmp.leftshift(1,false);
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}
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return r;
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}
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//this is GF(2^n) multiplication
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bitvector bitvector::field_mult(const bitvector &rhs, const bitvector &irpolynom) const
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{
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int d=irpolynom.degree();
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if(d>size()||d>rhs.size()) laerror("inconsistent dimensions in field_mult");
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bitvector r(size());
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r.clear();
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bitvector tmp(*this);
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tmp.resize(size()+1,true);
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tmp.copyonwrite();
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int rd=rhs.degree();
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for(int i=0; i<=rd; ++i) //avoid making a working copy of rhs and shifting it
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{
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if(rhs[i]) r+= tmp;
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tmp.leftshift(1,false);
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if(tmp[d]) tmp -= irpolynom;
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}
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return r;
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}
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//this is GF(2^n) multiplicative inverseion
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//cf. https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm
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bitvector bitvector::field_inv(const bitvector &irpolynom) const
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{
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int d=irpolynom.degree();
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if(d>size()) laerror("inconsistent dimensions in field_inv");
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bitvector t(size()); t.clear();
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bitvector newt(size()); newt.clear(); newt.set(0);
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bitvector r(irpolynom); r.copyonwrite();
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bitvector newr(*this); if(r.size()>newr.size()) newr.resize(r.size(),true); newr.copyonwrite();
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int rs=r.size();
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while(!newr.is_zero())
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{
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//std::cout <<"r "<<r<<" newr "<<newr <<" "; std::cout <<"t "<<t<<" newt "<<newt; std::cout <<std::endl;
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bitvector remainder(rs);
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bitvector quotient = r.division(newr,remainder);
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r=newr; newr=remainder;
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remainder= t - quotient.multiply(newt,false); //avoid size growth
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t=newt; newt=remainder;
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}
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if(r.degree()>0) laerror("field_inv: polynomial is not irreducible or input is zero modulo the polynomial");
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if(!r[0]) laerror("zero in field_inv");
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return t;
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}
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void bitvector::resize(const unsigned int n, bool preserve)
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{
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if(preserve) zero_padding();
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int oldnn=nn;
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NRVec<bitvector_block>::resize((n+blockbits-1)/blockbits,preserve);
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modulo=n%blockbits;
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if(preserve) //clear newly allocated memory
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{
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for(int i=oldnn; i<nn; ++i) v[i]=0;
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}
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else clear();
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}
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bitvector bitvector::division(const bitvector &rhs, bitvector &remainder) const
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{
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if(rhs.is_zero()) laerror("division by zero binary polynomial");
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if(is_zero() || rhs.is_one()) {remainder.clear(); return *this;}
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bitvector r(size());
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r.clear();
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remainder= *this;
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remainder.copyonwrite();
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int rhsd = rhs.degree();
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int d;
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while((d=remainder.degree()) >= rhsd)
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{
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unsigned int pos = d-rhsd;
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r.set(pos);
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remainder -= rhs<<pos;
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}
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remainder.resize(rhs.size(),true);
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return r;
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}
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bitvector bitvector::gcd(const bitvector &rhs) const
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{
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bitvector big,small;
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if(degree()>=rhs.degree())
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{big= *this; small=rhs;}
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else
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{big=rhs; small= *this;}
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if(big.is_zero())
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{
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if(small.is_zero()) laerror("two zero arguments in gcd");
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return small;
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}
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if(small.is_zero()) return big;
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if(small.is_one()) return small;
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if(big.is_one()) return big;
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do {
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bitvector help=small;
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small= big%small;
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big=help;
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}
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while(! small.is_zero());
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return big;
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}
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//cf. Brent & Zimmermann ANZMC08t (2008) paper
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//
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bool bitvector::is_irreducible() const
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{
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bitvector tmp(size());
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tmp.clear(); tmp.set(1);
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unsigned int d=degree();
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//repeated squaring test
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for(unsigned int j=0; j<d; ++j) tmp = tmp.field_mult(tmp,*this);
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tmp.flip(1);
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if(!tmp.is_zero()) return false;
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FACTORIZATION<uint64_t> f = factorization((uint64_t)d);
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if(f.begin()->first==d) return true; //d was prime
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//additional tests needed for non-prime degrees
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for(auto p=f.begin(); p!=f.end(); ++p)
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{
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unsigned int dm= d / p->first;
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tmp.clear(); tmp.set(1);
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for(unsigned int j=0; j<dm; ++j) tmp = tmp.field_mult(tmp,*this);
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tmp.flip(1);
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bitvector g=tmp.gcd(*this);
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//std::cout << "TEST tmp, ir, gcd, is_one "<<tmp<<" "<<*this<<" "<<g<<" : "<<g.is_one()<<std::endl;
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if(!g.is_one()) return false;
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}
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return true;
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}
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//horner scheme
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bitvector bitvector::composition(const bitvector &x) const
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{
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bitvector r(size());
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r.clear();
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int d=degree();
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for(int i=d; i>0; --i)
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{
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if((*this)[i]) r.flip(0);
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r*=x;
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}
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if((*this)[0]) r.flip(0);
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return r;
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}
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bitvector bitvector::field_composition(const bitvector &x, const bitvector &ir) const
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{
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bitvector r(size());
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r.clear();
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int d=degree();
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for(int i=d; i>0; --i)
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{
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if((*this)[i]) r.flip(0);
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r= r.field_mult(x,ir);
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}
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if((*this)[0]) r.flip(0);
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return r;
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}
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void bitvector::read(int fd, bool dimensions, bool transp)
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{
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if(dimensions)
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{
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int r = ::read(fd,&modulo,sizeof(modulo));
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if(r!=sizeof(modulo)) laerror("cannot read in bitvector");
|
|
}
|
|
NRVec<bitvector_block>::get(fd,dimensions,transp);
|
|
}
|
|
|
|
void bitvector::write(int fd, bool dimensions, bool transp)
|
|
{
|
|
if(dimensions)
|
|
{
|
|
int r = ::write(fd,&modulo,sizeof(modulo));
|
|
if(r!=sizeof(modulo)) laerror("cannot write in bitvector");
|
|
}
|
|
NRVec<bitvector_block>::put(fd,dimensions,transp);
|
|
}
|
|
|
|
static bitvector *tryme;
|
|
static bool irfound;
|
|
static int mynth;
|
|
|
|
static void irfinder(int nones, int top)
|
|
{
|
|
if(irfound) return;
|
|
if(nones==0) //terminate recursion
|
|
{
|
|
bool testit = tryme->is_irreducible();
|
|
//std::cout <<"candidate = "<< *tryme<< " result = "<<testit<<std::endl;
|
|
if(testit)
|
|
{
|
|
--mynth;
|
|
if(!mynth) irfound=true;
|
|
}
|
|
return;
|
|
}
|
|
for(int i=nones; i<=top; ++i)
|
|
{
|
|
tryme->set(i);
|
|
irfinder(nones-1,i-1);
|
|
if(irfound) break;
|
|
else tryme->reset(i);
|
|
}
|
|
}
|
|
|
|
|
|
bitvector find_irreducible(int deg, int pop, int nth)
|
|
{
|
|
if(deg<=0) laerror("illegal degree in find_irreducible");
|
|
if(deg==1) {bitvector r(2); r.set(1); r.reset(0); return r;}
|
|
bitvector r(deg+1);
|
|
if(pop== -1)
|
|
{
|
|
do {
|
|
r.randomize();
|
|
r.set(0);
|
|
r.set(deg);
|
|
if((r.population()&1)==0) r.flip(1+RANDINT32()%(deg-2));
|
|
}
|
|
while(!r.is_irreducible());
|
|
return r;
|
|
}
|
|
if(pop<3 || (pop&1)==0) laerror("impossible population of irreducible polynomial requested");
|
|
r.clear();
|
|
r.set(0);
|
|
r.set(deg);
|
|
pop-=2;
|
|
tryme= &r;
|
|
irfound=false;
|
|
mynth=nth;
|
|
irfinder(pop,deg-1);
|
|
if(!irfound) r.clear();
|
|
return r;
|
|
}
|
|
|
|
|
|
|
|
bitvector bitvector::pow(unsigned int n) const
|
|
{
|
|
if(n==0) {bitvector r(size()); r.clear(); r.set(0); return r;}
|
|
if(n==1) return *this;
|
|
bitvector y,z;
|
|
z= *this;
|
|
while(!(n&1))
|
|
{
|
|
z = z*z;
|
|
n >>= 1;
|
|
}
|
|
y=z;
|
|
while((n >>= 1)/*!=0*/)
|
|
{
|
|
z = z*z;
|
|
if(n&1) y *= z;
|
|
}
|
|
return y;
|
|
}
|
|
|
|
bitvector bitvector::field_pow(unsigned int n, const bitvector &ir) const
|
|
{
|
|
if(n==0) {bitvector r(size()); r.clear(); r.set(0); return r;}
|
|
if(n==1) return *this;
|
|
bitvector y,z;
|
|
z= *this;
|
|
while(!(n&1))
|
|
{
|
|
z = z.field_mult(z,ir);
|
|
n >>= 1;
|
|
}
|
|
y=z;
|
|
while((n >>= 1)/*!=0*/)
|
|
{
|
|
z = z.field_mult(z,ir);
|
|
if(n&1) y = y.field_mult(z,ir);
|
|
}
|
|
return y;
|
|
}
|
|
|
|
//sqrt(x) is x^(2^(d-1))
|
|
bitvector bitvector::field_sqrt(const bitvector &ir) const
|
|
{
|
|
int d=ir.degree();
|
|
bitvector r(*this);
|
|
for(int i=0; i<d-1; ++i)
|
|
{
|
|
r= r.field_mult(r,ir);
|
|
}
|
|
r.resize(d+1,true);
|
|
return r;
|
|
}
|
|
|
|
|
|
|
|
}//namespace
|