trunc.hpp

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// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2021 Tobias Hienzsch
 
#ifndef TETL_CMATH_TRUNC_HPP
#define TETL_CMATH_TRUNC_HPP
 
#include <etl/_config/all.hpp>
 
#include <etl/_3rd_party/gcem/gcem.hpp>
#include <etl/_concepts/integral.hpp>
#include <etl/_type_traits/is_constant_evaluated.hpp>
#include <etl/_type_traits/is_same.hpp>
 
namespace etl {
 
namespace detail {
template <typename T>
[[nodiscard]] constexpr auto trunc(T arg) noexcept -> T
{
    if (not is_constant_evaluated()) {
        if constexpr (is_same_v<T, float>) {
#if __has_builtin(__builtin_truncf)
            return __builtin_truncf(arg);
#endif
        }
        if constexpr (is_same_v<T, double>) {
#if __has_builtin(__builtin_trunc)
            return __builtin_trunc(arg);
#endif
        }
    }
 
    return detail::gcem::trunc(arg);
}
} // namespace detail
 
/// \ingroup cmath
/// @{
 
/// Computes the nearest integer not greater in magnitude than arg.
/// \details https://en.cppreference.com/w/cpp/numeric/math/trunc
/// \ingroup cmath
[[nodiscard]] constexpr auto trunc(float arg) noexcept -> float
{
    return detail::trunc(arg);
}
[[nodiscard]] constexpr auto truncf(float arg) noexcept -> float
{
    return detail::trunc(arg);
}
[[nodiscard]] constexpr auto trunc(double arg) noexcept -> double
{
    return detail::trunc(arg);
}
[[nodiscard]] constexpr auto trunc(long double arg) noexcept -> long double
{
    return detail::trunc(arg);
}
[[nodiscard]] constexpr auto truncl(long double arg) noexcept -> long double
{
    return detail::trunc(arg);
}
[[nodiscard]] constexpr auto trunc(integral auto arg) noexcept -> double
{
    return detail::trunc(double(arg));
}
 
/// @}
 
} // namespace etl
 
#endif // TETL_CMATH_TRUNC_HPP