LA_library/bitvector.h

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/*
LA: linear algebra C++ interface library
Copyright (C) 2008 Jiri Pittner <jiri.pittner@jh-inst.cas.cz> or <jiri@pittnerovi.com>
This program 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 3 of the License, or
(at your option) any later version.
This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
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#ifndef _BITVECTOR_H_
#define _BITVECTOR_H_
#include "vec.h"
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namespace LA {
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//compressed storage of large bit vectors
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//any reasonable compiler changes the dividions and modulos to shift/and instructions
typedef unsigned long bitvector_block; //should be automatically portable and efficiently use wordlength of each machine (32 vs 64)
#define blockbits (8*sizeof(bitvector_block))
inline unsigned int bitvector_rounded(unsigned int n)
{
return ((n+blockbits-1)/blockbits)*blockbits;
}
class bitvector : public NRVec<bitvector_block>
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{
private:
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unsigned int modulo;
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public:
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bitvector() : NRVec<bitvector_block>() {};
explicit bitvector (const unsigned int n):NRVec<bitvector_block>((n+blockbits-1)/blockbits) {modulo=n%blockbits;};
bitvector (const bitvector_block a, const unsigned int n):NRVec<bitvector_block>(a,(n+blockbits-1)/blockbits) {modulo=n%blockbits;};
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bitvector(const bitvector &rhs) : NRVec<bitvector_block>(rhs) {modulo=rhs.modulo;};
//operator= seems to be correctly synthetized by the compiler
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//override dereferencing to address single bits, is however possible
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//only in the const context (otherwise we would have to define a type which, when assigned to, changes a single bit - possible but probably inefficient)
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void resize(const unsigned int n) {NRVec<bitvector_block>::resize((n+blockbits-1)/blockbits); modulo=n%blockbits;};
unsigned int size() const {return (nn*blockbits)-blockbits+(modulo?modulo:blockbits);};
//arguments must be unsigned to keep the resulting assembly code simple and efficient
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const bool operator[](const unsigned int i) const {return (v[i/blockbits] >>(i%blockbits))&1UL;};
bitvector_block getblock(const unsigned int i) const {return v[i];}; //integer interpretation
void setblock(const unsigned int i, const bitvector_block b) {v[i]=b;};
int getblocksize() const {return 8*sizeof(bitvector_block);};
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void set(const unsigned int i) {v[i/blockbits] |= (1UL<<(i%blockbits));};
void reset(const unsigned int i) {v[i/blockbits] &= ~(1UL<<(i%blockbits));};
const bool get(const unsigned int i) {return (v[i/blockbits] >>(i%blockbits))&1UL;};
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const bool assign(const unsigned int i, const bool r) {if(r) set(i); else reset(i); return r;};
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void clear() {copyonwrite(true); memset(v,0,nn*sizeof(bitvector_block));};
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void fill() {memset(v,0xff,nn*sizeof(bitvector_block));};
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bool operator!=(const bitvector &rhs) const;
bool operator==(const bitvector &rhs) const {return !(*this != rhs);};
bool operator>(const bitvector &rhs) const;
bool operator<(const bitvector &rhs) const;
bool operator>=(const bitvector &rhs) const {return !(*this < rhs);};
bool operator<=(const bitvector &rhs) const {return !(*this > rhs);};
bitvector operator~() const;
bitvector& operator&=(const bitvector &rhs);
bitvector& operator|=(const bitvector &rhs);
bitvector& operator^=(const bitvector &rhs);
bitvector operator&(const bitvector &rhs) const {return bitvector(*this) &= rhs;};
bitvector operator|(const bitvector &rhs) const {return bitvector(*this) |= rhs;};
bitvector operator^(const bitvector &rhs) const {return bitvector(*this) ^= rhs;};
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unsigned int operator%(const bitvector &y) const; //number of differing bits
unsigned int population(const unsigned int before=0) const; //number of 1's
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//extended, truncated const i.e. not on *this but return new entity, take care of modulo's bits
//logical shifts <<= >>= << >> not implemented yet
//logical rotations not implemented yet
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//unformatted file IO
void read(int fd, bool dimensions=1, bool transp=0);
void write(int fd, bool dimensions=1, bool transp=0);
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};
//expand to separate bytes or ints
template <typename T>
void bitvector_expand(const bitvector &v, NRVec<T> &r)
{
int n=v.size();
r.resize(n);
r.clear();
for(int i=0; i<n; ++i) if(v[i]) r[i]=1;
}
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//mantissa of a floating number between 0 and 1
template <typename T>
bitvector mantissa(T x, int nbits, int shift=0)
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{
while(shift >0) {x+=x; --shift;}
while(shift <0) {x*=.5; ++shift;}
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if(x<0||x>=1) laerror("number not normalized in bitvector mantissa");
bitvector b(nbits);
b.clear();
T y= x+x;
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for(int i=0; i<nbits-1; ++i)
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{
int n= (int) y;
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if(n&1) b.set(i+1);
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y += y;
}
return b;
}
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template <typename T>
void bitvector_decimal(T &x, const bitvector &b, int shift=0)
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{
x=0;
for(int i=b.size()-1; i>=0; --i) if(b[i]) x += 1./(1ULL<<i);
while(shift >0) {x+=x; --shift;}
while(shift <0) {x*=.5; ++shift;}
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}
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template <typename T>
void bitvector_compress(bitvector &r, const NRVec<T> &v)
{
int n=v.size();
r.resize(n);
r.clear();
for(int i=0; i<n; ++i) if(v[i]) r.set(i);
}
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extern std::ostream & operator<<(std::ostream &s, const bitvector &x);
extern std::istream & operator>>(std::istream &s, bitvector &x);
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class bitvector_from1 : public bitvector
{
public:
bitvector_from1() : bitvector() {};
bitvector_from1(const bitvector &rhs) :bitvector(rhs) {};
explicit bitvector_from1(const unsigned int n) : bitvector(n) {};
const bool operator[](const unsigned int i) {return bitvector::operator[](i-1);};
void set(const unsigned int i) {bitvector::set(i-1);};
void reset(const unsigned int i) {bitvector::reset(i-1);};
const bool get(const unsigned int i) {return bitvector::get(i-1);};
const bool assign(const unsigned int i, const bool r) {return bitvector::assign(i-1,r);};
unsigned int population(const unsigned int before=0) const {return bitvector::population(before?before-1:0);};
};
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}//namespace
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#endif