diff options
Diffstat (limited to 'include/math.h')
-rw-r--r-- | include/math.h | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/include/math.h b/include/math.h index b7659267e..b61c2253d 100644 --- a/include/math.h +++ b/include/math.h @@ -1426,6 +1426,40 @@ trunc(_A1 __lcpp_x) _NOEXCEPT {return ::trunc((double)__lcpp_x);} #endif // !(defined(_LIBCPP_MSVCRT) && ((_VC_CRT_MAJOR_VERSION-0) < 14)) +_LIBCPP_BEGIN_NAMESPACE_STD + +template <class _IntT, class _FloatT, + bool _FloatBigger = (numeric_limits<_FloatT>::digits > numeric_limits<_IntT>::digits), + int _Bits = (numeric_limits<_IntT>::digits - numeric_limits<_FloatT>::digits)> +_LIBCPP_INLINE_VISIBILITY +_LIBCPP_CONSTEXPR _IntT __max_representable_int_for_float() _NOEXCEPT { + static_assert(is_floating_point<_FloatT>::value, "must be a floating point type"); + static_assert(is_integral<_IntT>::value, "must be an integral type"); + static_assert(numeric_limits<_FloatT>::radix == 2, "FloatT has incorrect radix"); + static_assert(_IsSame<_FloatT, float>::value || _IsSame<_FloatT, double>::value + || _IsSame<_FloatT,long double>::value, "unsupported floating point type"); + return _FloatBigger ? numeric_limits<_IntT>::max() : (numeric_limits<_IntT>::max() >> _Bits << _Bits); +} + +// Convert a floating point number to the specified integral type after +// clamping to the integral types representable range. +// +// The behavior is undefined if `__r` is NaN. +template <class _IntT, class _RealT> +_LIBCPP_INLINE_VISIBILITY +_IntT __clamp_to_integral(_RealT __r) _NOEXCEPT { + using _Lim = std::numeric_limits<_IntT>; + const _IntT _MaxVal = std::__max_representable_int_for_float<_IntT, _RealT>(); + if (__r >= ::nextafter(static_cast<_RealT>(_MaxVal), INFINITY)) { + return _Lim::max(); + } else if (__r <= _Lim::lowest()) { + return _Lim::min(); + } + return static_cast<_IntT>(__r); +} + +_LIBCPP_END_NAMESPACE_STD + } // extern "C++" #endif // __cplusplus |