bitfield.hpp

/*
 * This file was written by Aldo Fregoso, and is placed in the public domain.
 * The author hereby disclaims copyright to this source code.
 */

#ifndef UTIL_BITFIELD_H
#define UTIL_BITFIELD_H

#include <inttypes.h>

class bitfield32_t
{
    uint_fast32_t m_field = 0;

public:
    inline bool get( const size_t pos ) const
        { return (bool)(m_field & (1 << pos)); }
    inline bool operator[]( const size_t pos ) const
        { return get(pos); }
    inline uint_fast32_t getField() const
        { return m_field; }
    inline bool isEmpty() const
        { return m_field == 0; }

    inline void set( const size_t pos )
        { m_field |= 1 << pos; }
    inline void clear( const size_t pos )
        { m_field &= ~(1 << pos); }
    inline void toggle( const size_t pos )
        { m_field ^= 1 << pos; }
    inline void setAll()
        { m_field = ~0; }
    inline void clearAll()
        { m_field = 0; }
    inline void toggleAll()
        { m_field ^= ~0; }

    uint_fast32_t getNumSettedBits() const {
        //
        // Code Taken from:
        // http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
        //
        uint_fast32_t bits = getField();
        bits = bits - ((bits >> 1) & 0x55555555);
        bits = (bits & 0x33333333) + ((bits >> 2) & 0x33333333);
        return ((bits + (bits >> 4) & 0xF0F0F0F) * 0x1010101) >> 24;
    }
    uint_fast32_t getNumClearedBits() const
        { return 32 - getNumSettedBits(); }

    inline void operator=( const bitfield32_t& other ) { m_field = other.m_field; }
    inline bool operator==( const bitfield32_t& other ) const { return m_field == other.m_field; }
    inline bool operator!=( const bitfield32_t& other ) const { return m_field != other.m_field; }
};

#endif