floor.hpp

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// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2019 Tobias Hienzsch
 
#ifndef TETL_CHRONO_FLOOR_HPP
#define TETL_CHRONO_FLOOR_HPP
 
#include <etl/_chrono/duration_cast.hpp>
#include <etl/_chrono/time_point_cast.hpp>
#include <etl/_type_traits/is_arithmetic.hpp>
 
namespace etl::chrono {
 
/// \brief Returns the greatest duration t representable in ToDuration that is
/// less or equal to d. The function does not participate in the overload
/// resolution unless ToDuration is an instance of etl::chrono::duration.
/// \ingroup chrono
template <typename To, typename Rep, typename Period>
    requires(detail::is_duration_v<To>)
[[nodiscard]] constexpr auto
floor(duration<Rep, Period> const& d) noexcept(is_arithmetic_v<Rep> and is_arithmetic_v<typename To::rep>) -> To
{
    auto const t{duration_cast<To>(d)};
    if (t > d) {
        return To(t.count() - static_cast<typename To::rep>(1));
    }
    return t;
}
 
/// \ingroup chrono
template <typename To, typename Clock, typename Duration>
    requires(detail::is_duration_v<To>)
[[nodiscard]] constexpr auto floor(time_point<Clock, Duration> const& tp) -> time_point<Clock, To>
{
    return time_point<Clock, To>(floor<To>(tp.time_since_epoch()));
}
 
} // namespace etl::chrono
 
#endif // TETL_CHRONO_FLOOR_HPP