Added thirdparty: boost library

thirdparty/include/boost/math/ccmath/ilogb.hpp

@@ -0,0 +1,60 @@
+//  (C) Copyright Matt Borland 2021.
+//  Use, modification and distribution are subject to the
+//  Boost Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#ifndef BOOST_MATH_CCMATH_ILOGB_HPP
+#define BOOST_MATH_CCMATH_ILOGB_HPP
+
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/ilogb.hpp> can only be used in C++17 and later."
+#endif
+
+#include <boost/math/ccmath/logb.hpp>
+#include <boost/math/ccmath/isinf.hpp>
+#include <boost/math/ccmath/isnan.hpp>
+#include <boost/math/ccmath/abs.hpp>
+
+namespace boost::math::ccmath {
+
+// If arg is not zero, infinite, or NaN, the value returned is exactly equivalent to static_cast<int>(std::logb(arg))
+template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
+inline constexpr int ilogb(Real arg) noexcept
+{
+    if(BOOST_MATH_IS_CONSTANT_EVALUATED(arg))
+    {
+        return boost::math::ccmath::abs(arg) == Real(0) ? FP_ILOGB0 :
+               boost::math::ccmath::isinf(arg) ? INT_MAX :
+               boost::math::ccmath::isnan(arg) ? FP_ILOGBNAN :
+               static_cast<int>(boost::math::ccmath::logb(arg));
+    }
+    else
+    {
+        using std::ilogb;
+        return ilogb(arg);
+    }
+}
+
+template <typename Z, std::enable_if_t<std::is_integral_v<Z>, bool> = true>
+inline constexpr int ilogb(Z arg) noexcept
+{
+    return boost::math::ccmath::ilogb(static_cast<double>(arg));
+}
+
+inline constexpr int ilogbf(float arg) noexcept
+{
+    return boost::math::ccmath::ilogb(arg);
+}
+
+#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
+inline constexpr int ilogbl(long double arg) noexcept
+{
+    return boost::math::ccmath::ilogb(arg);
+}
+#endif
+
+} // Namespaces
+
+#endif // BOOST_MATH_CCMATH_ILOGB_HPP