forked from OSchip/llvm-project
61 lines
2.2 KiB
C++
61 lines
2.2 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___RANDOM_CLAMP_TO_INTEGRAL_H
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#define _LIBCPP___RANDOM_CLAMP_TO_INTEGRAL_H
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#include <__config>
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#include <cmath>
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#include <limits>
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#include <type_traits>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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template <class _IntT, class _FloatT,
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bool _FloatBigger = (numeric_limits<_FloatT>::digits > numeric_limits<_IntT>::digits),
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int _Bits = (numeric_limits<_IntT>::digits - numeric_limits<_FloatT>::digits)>
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_LIBCPP_INLINE_VISIBILITY
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_LIBCPP_CONSTEXPR _IntT __max_representable_int_for_float() _NOEXCEPT {
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static_assert(is_floating_point<_FloatT>::value, "must be a floating point type");
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static_assert(is_integral<_IntT>::value, "must be an integral type");
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static_assert(numeric_limits<_FloatT>::radix == 2, "FloatT has incorrect radix");
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static_assert((_IsSame<_FloatT, float>::value || _IsSame<_FloatT, double>::value
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|| _IsSame<_FloatT,long double>::value), "unsupported floating point type");
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return _FloatBigger ? numeric_limits<_IntT>::max() : (numeric_limits<_IntT>::max() >> _Bits << _Bits);
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}
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// Convert a floating point number to the specified integral type after
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// clamping to the integral type's representable range.
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//
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// The behavior is undefined if `__r` is NaN.
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template <class _IntT, class _RealT>
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_LIBCPP_INLINE_VISIBILITY
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_IntT __clamp_to_integral(_RealT __r) _NOEXCEPT {
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using _Lim = numeric_limits<_IntT>;
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const _IntT _MaxVal = __max_representable_int_for_float<_IntT, _RealT>();
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if (__r >= ::nextafter(static_cast<_RealT>(_MaxVal), INFINITY)) {
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return _Lim::max();
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} else if (__r <= _Lim::lowest()) {
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return _Lim::min();
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}
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return static_cast<_IntT>(__r);
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}
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___RANDOM_CLAMP_TO_INTEGRAL_H
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