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// bitspace.cc: implementation of class bitspace for handling F_2 spaces
//////////////////////////////////////////////////////////////////////////
//
// Copyright 1990-2012 John Cremona
//
// This file is part of the eclib package.
//
// eclib is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2 of the License, or (at your
// option) any later version.
//
// eclib is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License
// along with eclib; if not, write to the Free Software Foundation,
// Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
//
//////////////////////////////////////////////////////////////////////////
#include <iostream>
#include <eclib/interface.h>
#include <eclib/bitspace.h>
using namespace std;
bitspace::bitspace(long d)
{
if(d<0)
{
cout<<"Error in bitspace constructor with negative dimension "<<d
<<"! replacing with 0\n";
d=0;
}
if(d>NTL_BITS_PER_LONG)
{
cout<<"Error in bitspace constructor with dimension "<<d
<<">" <<NTL_BITS_PER_LONG<<"! replacing with "
<<NTL_BITS_PER_LONG<<"\n";
d=NTL_BITS_PER_LONG;
}
maxdim=d;
pivs = new long[maxdim];
gens = new unsigned long[maxdim];
dim=0;
bitmask=0;
}
bitspace::~bitspace()
{
delete[]pivs;
delete[]gens;
}
long bitspace::reduce(unsigned long& v, long start) const
{
long j;
for(j=start; j<dim; j++) if(testbit(v,pivs[j])) {v=v^gens[j];}
for(j=maxdim-1; j>=0; j--) if(testbit(v,j)) {return j;}
return -1;
}
void bitspace::augment(unsigned long v, long piv)
{
gens[dim]=v;
pivs[dim]=piv;
bitmask |= (1<<piv);
dim++;
}
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