galois.hpp

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/*
 * Copyright (C) 1998-2018 ALPS Collaboration. See COPYRIGHT.TXT
 * All rights reserved. Use is subject to license terms. See LICENSE.TXT
 * For use in publications, see ACKNOWLEDGE.TXT
 */
#pragma once

#include <alps/alea/core.hpp>

namespace alps { namespace alea { namespace internal {

class galois_hopper
{
public:
    galois_hopper(size_t size);

    galois_hopper &operator++();

    galois_hopper operator++(int);

    void reset(bool merge_mode=false);

    size_t current() const { return current_; }

    bool merge_mode() const { return level_ != 0; }

    size_t merge_into() const { return (current_ + skip_) % (size_ + 1); }

    double factor() const { return factor_; }

    size_t level() const { return level_; }

    size_t cycle() const { return cycle_; }

private:
    void advance_fill();
    void advance_galois();

    size_t size_;
    size_t level_, factor_;
    size_t current_, skip_, level_pos_, cycle_;
};

}}}