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-rw-r--r--include/cmath36
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