scale.h

 
//          Copyright John McFarlane 2019.
// Distributed under the Boost Software License, Version 1.0.
//    (See accompanying file ../LICENSE_1_0.txt or copy at
//          http://www.boost.org/LICENSE_1_0.txt)
 
#if !defined(CNL_IMPL_ELASTIC_INTEGER_H)
#define CNL_IMPL_ELASTIC_INTEGER_H
 
#include "../num_traits/from_rep.h"
#include "../num_traits/rep_of.h"
#include "../num_traits/scale.h"
#include "../num_traits/to_rep.h"
#include "definition.h"
 
#include <type_traits>
 
namespace cnl {
    template<int ShiftDigits, int ScaleRadix, int ScalarDigits, class ScalarNarrowest>
    requires(0 <= ShiftDigits) struct scale<
            ShiftDigits, ScaleRadix, elastic_integer<ScalarDigits, ScalarNarrowest>> {
        [[nodiscard]] constexpr auto operator()(
                elastic_integer<ScalarDigits, ScalarNarrowest> const& s) const
                -> elastic_integer<ShiftDigits + ScalarDigits, ScalarNarrowest>
        {
            using result_type = elastic_integer<ShiftDigits + ScalarDigits, ScalarNarrowest>;
            using result_rep = _impl::rep_of_t<result_type>;
            return _impl::from_rep<result_type>(
                    scale<ShiftDigits, ScaleRadix, result_rep>()(_impl::to_rep(s)));
        }
    };
 
    template<int ShiftDigits, int ScalarDigits, class ScalarNarrowest>
    requires(ShiftDigits < 0) struct scale<
            ShiftDigits, 2, elastic_integer<ScalarDigits, ScalarNarrowest>> {
        [[nodiscard]] constexpr auto operator()(
                elastic_integer<ScalarDigits, ScalarNarrowest> const& s) const
                -> elastic_integer<ShiftDigits + ScalarDigits, ScalarNarrowest>
        {
            using divisor_type = elastic_integer<1 - ShiftDigits, ScalarNarrowest>;
            using divisor_rep = _impl::rep_of_t<divisor_type>;
            return _impl::to_rep(s) / (divisor_rep{1} << -ShiftDigits);
        }
    };
}
 
#endif  // CNL_IMPL_ELASTIC_INTEGER_H