LA_library/bitvector.h

#ifndef _BITVECTOR_H_
#define _BITVECTOR_H_

#include "vec.h"

//compressed storage of large bit vectors
//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>
	{
private:
	unsigned int modulo;
public:
	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;};
	bitvector(const bitvector &rhs) : NRVec<bitvector_block>(rhs) {};
	//override dereferencing to address single bits, is however possible
	//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)
	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
        const bool operator[](const unsigned int i) const {return (v[i/blockbits] >>(i%blockbits))&1;};
	void set(const unsigned int i) {v[i/blockbits] |= (1<<(i%blockbits));};
	void reset(const unsigned int i) {v[i/blockbits] &= ~(1<<(i%blockbits));};
	const bool get(const unsigned int i) {return (v[i/blockbits] >>(i%blockbits))&1;};
	const bool assign(const unsigned int i, const bool r) {if(r) set(i); else reset(i); return r;};
	void clear() {memset(v,0,nn*sizeof(bitvector_block));};
	void fill() {memset(v,0xff,nn*sizeof(bitvector_block));};
	const bool operator!=(const bitvector &rhs) const {};
	const bool operator==(const bitvector &rhs) const {return !(*this != rhs);};
	};


extern ostream & operator<<(ostream &s, const bitvector &x);
extern istream & operator>>(istream  &s, bitvector &x);

#endif