585da50d7d
This PR adds the code of Boost.Math as of version 1.89 into the third-party directory, as discussed in a recent RFC [1]. The goal is for this code to be used as a back-end for the C++17 Math Special Functions. As explained in third-paty/README.md, this code is cleared for usage inside libc++ for the Math Special functions, however the LLVM Foundation should be consulted before using this code anywhere else in the LLVM project, due to the fact that it is under the Boost Software License (as opposed to the usual LLVM license). See the RFC [1] for more details. [1]: https://discourse.llvm.org/t/rfc-libc-taking-a-dependency-on-boost-math-for-the-c-17-math-special-functions
102 lines
2.4 KiB
C++
102 lines
2.4 KiB
C++
// (C) Copyright Christopher Kormanyos 1999 - 2021.
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// (C) Copyright Matt Borland 2021.
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MATH_CCMATH_FREXP_HPP
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#define BOOST_MATH_CCMATH_FREXP_HPP
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#include <boost/math/ccmath/detail/config.hpp>
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#ifdef BOOST_MATH_NO_CCMATH
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#error "The header <boost/math/frexp.hpp> can only be used in C++17 and later."
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#endif
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#include <boost/math/ccmath/isinf.hpp>
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#include <boost/math/ccmath/isnan.hpp>
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#include <boost/math/ccmath/isfinite.hpp>
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namespace boost::math::ccmath {
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namespace detail
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{
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template <typename Real>
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inline constexpr Real frexp_zero_impl(Real arg, int* exp)
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{
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*exp = 0;
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return arg;
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}
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template <typename Real>
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inline constexpr Real frexp_impl(Real arg, int* exp)
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{
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const bool negative_arg = (arg < Real(0));
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Real f = negative_arg ? -arg : arg;
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int e2 = 0;
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constexpr Real two_pow_32 = Real(4294967296);
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while (f >= two_pow_32)
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{
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f = f / two_pow_32;
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e2 += 32;
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}
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while(f >= Real(1))
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{
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f = f / Real(2);
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++e2;
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}
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if(exp != nullptr)
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{
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*exp = e2;
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}
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return !negative_arg ? f : -f;
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}
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} // namespace detail
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template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
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inline constexpr Real frexp(Real arg, int* exp)
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{
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if(BOOST_MATH_IS_CONSTANT_EVALUATED(arg))
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{
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return arg == Real(0) ? detail::frexp_zero_impl(arg, exp) :
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arg == Real(-0) ? detail::frexp_zero_impl(arg, exp) :
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boost::math::ccmath::isinf(arg) ? detail::frexp_zero_impl(arg, exp) :
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boost::math::ccmath::isnan(arg) ? detail::frexp_zero_impl(arg, exp) :
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boost::math::ccmath::detail::frexp_impl(arg, exp);
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}
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else
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{
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using std::frexp;
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return frexp(arg, exp);
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}
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}
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template <typename Z, std::enable_if_t<std::is_integral_v<Z>, bool> = true>
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inline constexpr double frexp(Z arg, int* exp)
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{
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return boost::math::ccmath::frexp(static_cast<double>(arg), exp);
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}
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inline constexpr float frexpf(float arg, int* exp)
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{
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return boost::math::ccmath::frexp(arg, exp);
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}
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#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
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inline constexpr long double frexpl(long double arg, int* exp)
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{
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return boost::math::ccmath::frexp(arg, exp);
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}
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#endif
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}
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#endif // BOOST_MATH_CCMATH_FREXP_HPP
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