1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef _LIBCPP___RANDOM_CLAMP_TO_INTEGRAL_H
10 #define _LIBCPP___RANDOM_CLAMP_TO_INTEGRAL_H
11 
12 #include <__config>
13 #include <cmath>
14 #include <limits>
15 
16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17 #  pragma GCC system_header
18 #endif
19 
20 _LIBCPP_PUSH_MACROS
21 #include <__undef_macros>
22 
23 _LIBCPP_BEGIN_NAMESPACE_STD
24 
25 template <class _IntT, class _FloatT,
26     bool _FloatBigger = (numeric_limits<_FloatT>::digits > numeric_limits<_IntT>::digits),
27     int _Bits = (numeric_limits<_IntT>::digits - numeric_limits<_FloatT>::digits)>
28 _LIBCPP_INLINE_VISIBILITY
29 _LIBCPP_CONSTEXPR _IntT __max_representable_int_for_float() _NOEXCEPT {
30   static_assert(is_floating_point<_FloatT>::value, "must be a floating point type");
31   static_assert(is_integral<_IntT>::value, "must be an integral type");
32   static_assert(numeric_limits<_FloatT>::radix == 2, "FloatT has incorrect radix");
33   static_assert((_IsSame<_FloatT, float>::value || _IsSame<_FloatT, double>::value
34                  || _IsSame<_FloatT,long double>::value), "unsupported floating point type");
35   return _FloatBigger ? numeric_limits<_IntT>::max() :  (numeric_limits<_IntT>::max() >> _Bits << _Bits);
36 }
37 
38 // Convert a floating point number to the specified integral type after
39 // clamping to the integral type's representable range.
40 //
41 // The behavior is undefined if `__r` is NaN.
42 template <class _IntT, class _RealT>
43 _LIBCPP_INLINE_VISIBILITY
44 _IntT __clamp_to_integral(_RealT __r) _NOEXCEPT {
45   using _Lim = numeric_limits<_IntT>;
46   const _IntT __max_val = __max_representable_int_for_float<_IntT, _RealT>();
47   if (__r >= ::nextafter(static_cast<_RealT>(__max_val), INFINITY)) {
48     return _Lim::max();
49   } else if (__r <= _Lim::lowest()) {
50     return _Lim::min();
51   }
52   return static_cast<_IntT>(__r);
53 }
54 
55 _LIBCPP_END_NAMESPACE_STD
56 
57 _LIBCPP_POP_MACROS
58 
59 #endif // _LIBCPP___RANDOM_CLAMP_TO_INTEGRAL_H
60