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#include <type_traits>
16
17#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
18#  pragma GCC system_header
19#endif
20
21_LIBCPP_PUSH_MACROS
22#include <__undef_macros>
23
24_LIBCPP_BEGIN_NAMESPACE_STD
25
26template <class _IntT, 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_INLINE_VISIBILITY
30_LIBCPP_CONSTEXPR _IntT __max_representable_int_for_float() _NOEXCEPT {
31  static_assert(is_floating_point<_FloatT>::value, "must be a floating point type");
32  static_assert(is_integral<_IntT>::value, "must be an integral type");
33  static_assert(numeric_limits<_FloatT>::radix == 2, "FloatT has incorrect radix");
34  static_assert((_IsSame<_FloatT, float>::value || _IsSame<_FloatT, double>::value
35                 || _IsSame<_FloatT,long double>::value), "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_INLINE_VISIBILITY
45_IntT __clamp_to_integral(_RealT __r) _NOEXCEPT {
46  using _Lim = numeric_limits<_IntT>;
47  const _IntT _MaxVal = __max_representable_int_for_float<_IntT, _RealT>();
48  if (__r >= ::nextafter(static_cast<_RealT>(_MaxVal), INFINITY)) {
49    return _Lim::max();
50  } else if (__r <= _Lim::lowest()) {
51    return _Lim::min();
52  }
53  return static_cast<_IntT>(__r);
54}
55
56_LIBCPP_END_NAMESPACE_STD
57
58_LIBCPP_POP_MACROS
59
60#endif // _LIBCPP___RANDOM_CLAMP_TO_INTEGRAL_H
61