// BITSET2
//
//  Copyright Claas Bontus
//
//  Use, modification and distribution is subject to the
//  Boost Software License, Version 1.0. (See accompanying
//  file LICENSE.txt or copy at
//  http://www.boost.org/LICENSE_1_0.txt)
//
// Project home: https://github.com/ClaasBontus/bitset2
//


#pragma once

#include "bit_chars.hpp"

namespace detail
{


/// \brief Takes a variable 'v' of type LRGST_t
/// (unsigned long long or unsigned __int128)
/// and returns a std::array 'a' equivalent to v. 'a' represents
/// an N bit bitset2 with base_t == T.
template <size_t N, class T>
struct lrgst2array {
    using base_t  = T;
    using b_c     = bit_chars<N, T>;
    using LRGST_t = typename b_c::LRGST_t;

    enum : size_t {
        n_bits        = N,
        base_t_n_bits = b_c::base_t_n_bits,
        lrgst_n_bist  = b_c::lrgst_n_bist,
        n_array       = b_c::n_array,
        centrl_i      = ce_min((lrgst_n_bist - 1) / base_t_n_bits, n_array - 1),
        n_empty_vals  = n_array - centrl_i - 1
    };

    enum : base_t {
        hgh_bit_pattern = b_c::hgh_bit_pattern,
        use_pattern     = (n_empty_vals == 0) ? hgh_bit_pattern : base_t(~base_t(0))
    };

    using array_t = typename h_types<T>::template array_t<n_array>;

    constexpr array_t operator()(LRGST_t v) const noexcept
    {
        array_t retval = (detail::gen_empty_array<n_array, T>)();
        size_t  c      = 0;
        for (; c < centrl_i; ++c) {
            retval[c] = base_t(v);
            v         = ce_right_shift(v, base_t_n_bits);
        }
        retval[c] = base_t(v & use_pattern);
        return retval;
    }
}; // struct lrgst2array


} // namespace detail