99 lines
2.3 KiB
C++
99 lines
2.3 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 <cmath>
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#include <limits>
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#include <type_traits>
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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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