diff options
Diffstat (limited to 'include/cmath')
| -rw-r--r-- | include/cmath | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/include/cmath b/include/cmath index f5864be5e11a..0f06486fb34f 100644 --- a/include/cmath +++ b/include/cmath @@ -303,11 +303,15 @@ long double truncl(long double x); #include <__config> #include <math.h> #include <version> +#include <type_traits> #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) #pragma GCC system_header #endif +_LIBCPP_PUSH_MACROS +#include <__undef_macros> + _LIBCPP_BEGIN_NAMESPACE_STD using ::signbit; @@ -632,6 +636,38 @@ lerp(long double __a, long double __b, long double __t) _NOEXCEPT { return __ler #endif // _LIBCPP_STD_VER > 17 +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 +_LIBCPP_POP_MACROS + #endif // _LIBCPP_CMATH |