Add core/cmath.hpp

include/boost/core/cmath.hpp

@@ -0,0 +1,126 @@
+#ifndef BOOST_CORE_CMATH_HPP_INCLUDED
+#define BOOST_CORE_CMATH_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+// boost/core/cmath.hpp
+//
+// Floating point classification and sign manipulation functions
+// Extracted from https://github.com/boostorg/lexical_cast/pull/37
+//
+// Copyright 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <cmath>
+#if defined(_MSC_VER) && _MSC_VER < 1800
+# include <float.h>
+#endif
+
+namespace boost
+{
+namespace core
+{
+#if defined(_MSC_VER) && _MSC_VER < 1800
+
+template<class T> T copysign( T x, T y )
+{
+    return static_cast<T>( _copysign( static_cast<double>( x ), static_cast<double>( y ) ) );
+}
+
+template<class T> bool isnan( T x )
+{
+    return _isnan( static_cast<double>( x ) ) != 0;
+}
+
+template<class T> bool isfinite( T x )
+{
+    return _finite( static_cast<double>( x ) ) != 0;
+}
+
+template<class T> bool isinf( T x )
+{
+    return ( _fpclass( static_cast<double>( x ) ) & ( _FPCLASS_PINF | _FPCLASS_NINF ) ) != 0;
+}
+
+inline bool isnormal( float x )
+{
+    // no _fpclassf in 32 bit mode
+    unsigned y = reinterpret_cast< unsigned const& >( x );
+    unsigned exp = ( y >> 23 ) & 0xFF;
+    return exp != 0 && exp != 0xFF;
+}
+
+inline bool isnormal( double x )
+{
+    return ( _fpclass( x ) & ( _FPCLASS_PN | _FPCLASS_NN ) ) != 0;
+}
+
+inline bool isnormal( long double x )
+{
+    return boost::core::isnormal( static_cast<double>( x ) );
+}
+
+template<class T> bool signbit( T x )
+{
+    return _copysign( 1.0, static_cast<double>( x ) ) < 0.0;
+}
+
+#else
+
+using std::isfinite;
+using std::isnan;
+using std::isinf;
+using std::isnormal;
+
+using std::signbit;
+
+// std::copysign doesn't exist in libstdc++ under -std=c++03
+
+#if !defined(__GNUC__)
+
+template<class T> T copysign( T x, T y )
+{
+    return std::copysign( x, y );
+}
+
+#else
+
+namespace detail
+{
+
+// ::copysignl is unreliable, use the built-ins
+
+inline float copysign_impl( float x, float y )
+{
+    return __builtin_copysignf( x, y );
+}
+
+inline double copysign_impl( double x, double y )
+{
+    return __builtin_copysign( x, y );
+}
+
+inline long double copysign_impl( long double x, long double y )
+{
+    return __builtin_copysignl( x, y );
+}
+
+} // namespace detail
+
+template<class T> T copysign( T x, T y )
+{
+    return boost::core::detail::copysign_impl( x, y );
+}
+
+#endif // !defined(__GNUC__)
+#endif // #if defined(_MSC_VER) && _MSC_VER < 1800
+
+} // namespace core
+} // namespace boost
+
+#endif  // #ifndef BOOST_CORE_CMATH_HPP_INCLUDED