opencv/modules/flann/include/opencv2/flann/dynamic_bitset.h

/***********************************************************************
 * Software License Agreement (BSD License)
 *
 * Copyright 2008-2009  Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
 * Copyright 2008-2009  David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
 *
 * THE BSD LICENSE
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
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 *************************************************************************/

/***********************************************************************
 * Author: Vincent Rabaud
 *************************************************************************/

#ifndef OPENCV_FLANN_DYNAMIC_BITSET_H_
#define OPENCV_FLANN_DYNAMIC_BITSET_H_

#ifndef FLANN_USE_BOOST
#  define FLANN_USE_BOOST 0
#endif
//#define FLANN_USE_BOOST 1
#if FLANN_USE_BOOST
#include <boost/dynamic_bitset.hpp>
typedef boost::dynamic_bitset<> DynamicBitset;
#else

#include <limits.h>

#include "dist.h"

namespace cvflann {

/** Class re-implementing the boost version of it
 * This helps not depending on boost, it also does not do the bound checks
 * and has a way to reset a block for speed
 */
class DynamicBitset
{
public:
    /** default constructor
     */
    DynamicBitset() : size_(0)
    {
    }

    /** only constructor we use in our code
     * @param sz the size of the bitset (in bits)
     */
    DynamicBitset(size_t sz)
    {
        resize(sz);
        reset();
    }

    /** Sets all the bits to 0
     */
    void clear()
    {
        std::fill(bitset_.begin(), bitset_.end(), 0);
    }

    /** @brief checks if the bitset is empty
     * @return true if the bitset is empty
     */
    bool empty() const
    {
        return bitset_.empty();
    }

    /** set all the bits to 0
     */
    void reset()
    {
        std::fill(bitset_.begin(), bitset_.end(), 0);
    }

    /** @brief set one bit to 0
     * @param index
     */
    void reset(size_t index)
    {
        bitset_[index / cell_bit_size_] &= ~(size_t(1) << (index % cell_bit_size_));
    }

    /** @brief sets a specific bit to 0, and more bits too
     * This function is useful when resetting a given set of bits so that the
     * whole bitset ends up being 0: if that's the case, we don't care about setting
     * other bits to 0
     * @param index
     */
    void reset_block(size_t index)
    {
        bitset_[index / cell_bit_size_] = 0;
    }

    /** resize the bitset so that it contains at least sz bits
     * @param sz
     */
    void resize(size_t sz)
    {
        size_ = sz;
        bitset_.resize(sz / cell_bit_size_ + 1);
    }

    /** set a bit to true
     * @param index the index of the bit to set to 1
     */
    void set(size_t index)
    {
        bitset_[index / cell_bit_size_] |= size_t(1) << (index % cell_bit_size_);
    }

    /** gives the number of contained bits
     */
    size_t size() const
    {
        return size_;
    }

    /** check if a bit is set
     * @param index the index of the bit to check
     * @return true if the bit is set
     */
    bool test(size_t index) const
    {
        return (bitset_[index / cell_bit_size_] & (size_t(1) << (index % cell_bit_size_))) != 0;
    }

private:
    std::vector<size_t> bitset_;
    size_t size_;
    static const unsigned int cell_bit_size_ = CHAR_BIT * sizeof(size_t);
};

} // namespace cvflann

#endif

#endif // OPENCV_FLANN_DYNAMIC_BITSET_H_