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
25template <class _IntT,
26 class _FloatT,
27 bool _FloatBigger = (numeric_limits<_FloatT>::digits > numeric_limits<_IntT>::digits),
28 int _Bits = (numeric_limits<_IntT>::digits - numeric_limits<_FloatT>::digits)>
29_LIBCPP_HIDE_FROM_ABI _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(
34 (_IsSame<_FloatT, float>::value || _IsSame<_FloatT, double>::value || _IsSame<_FloatT, long double>::value),
35 "unsupported floating point type");
36 return _FloatBigger ? numeric_limits<_IntT>::max() : (numeric_limits<_IntT>::max() >> _Bits << _Bits);
37}
38
39// Convert a floating point number to the specified integral type after
40// clamping to the integral type's representable range.
41//
42// The behavior is undefined if `__r` is NaN.
43template <class _IntT, class _RealT>
44_LIBCPP_HIDE_FROM_ABI _IntT __clamp_to_integral(_RealT __r) _NOEXCEPT {
45 using _Lim = numeric_limits<_IntT>;
46 const _IntT __max_val = std::__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