// (C) Copyright John Maddock 2006. // (C) Copyright Johan Rade 2006. // (C) Copyright Paul A. Bristow 2011 (added changesign). // 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_TOOLS_SIGN_HPP #define BOOST_MATH_TOOLS_SIGN_HPP #ifdef _MSC_VER #pragma once #endif #include #include #include namespace boost{ namespace math{ namespace detail { // signbit #ifdef BOOST_MATH_USE_STD_FPCLASSIFY template inline int signbit_impl(T x, native_tag const&) { return (std::signbit)(x); } #endif // Generic versions first, note that these do not handle // signed zero or NaN. template inline int signbit_impl(T x, generic_tag const&) { return x < 0; } template inline int signbit_impl(T x, generic_tag const&) { return x < 0; } #if defined(__GNUC__) && (LDBL_MANT_DIG == 106) // // Special handling for GCC's "double double" type, // in this case the sign is the same as the sign we // get by casting to double, no overflow/underflow // can occur since the exponents are the same magnitude // for the two types: // inline int signbit_impl(long double x, generic_tag const&) { return (boost::math::signbit)(static_cast(x)); } inline int signbit_impl(long double x, generic_tag const&) { return (boost::math::signbit)(static_cast(x)); } #endif template inline int signbit_impl(T x, ieee_copy_all_bits_tag const&) { typedef BOOST_DEDUCED_TYPENAME fp_traits::type traits; BOOST_DEDUCED_TYPENAME traits::bits a; traits::get_bits(x,a); return a & traits::sign ? 1 : 0; } template inline int signbit_impl(T x, ieee_copy_leading_bits_tag const&) { typedef BOOST_DEDUCED_TYPENAME fp_traits::type traits; BOOST_DEDUCED_TYPENAME traits::bits a; traits::get_bits(x,a); return a & traits::sign ? 1 : 0; } // Changesign // Generic versions first, note that these do not handle // signed zero or NaN. template inline T (changesign_impl)(T x, generic_tag const&) { return -x; } template inline T (changesign_impl)(T x, generic_tag const&) { return -x; } #if defined(__GNUC__) && (LDBL_MANT_DIG == 106) // // Special handling for GCC's "double double" type, // in this case we need to change the sign of both // components of the "double double": // inline long double (changesign_impl)(long double x, generic_tag const&) { double* pd = reinterpret_cast(&x); pd[0] = boost::math::changesign(pd[0]); pd[1] = boost::math::changesign(pd[1]); return x; } inline long double (changesign_impl)(long double x, generic_tag const&) { double* pd = reinterpret_cast(&x); pd[0] = boost::math::changesign(pd[0]); pd[1] = boost::math::changesign(pd[1]); return x; } #endif template inline T changesign_impl(T x, ieee_copy_all_bits_tag const&) { typedef BOOST_DEDUCED_TYPENAME fp_traits::sign_change_type traits; BOOST_DEDUCED_TYPENAME traits::bits a; traits::get_bits(x,a); a ^= traits::sign; traits::set_bits(x,a); return x; } template inline T (changesign_impl)(T x, ieee_copy_leading_bits_tag const&) { typedef BOOST_DEDUCED_TYPENAME fp_traits::sign_change_type traits; BOOST_DEDUCED_TYPENAME traits::bits a; traits::get_bits(x,a); a ^= traits::sign; traits::set_bits(x,a); return x; } } // namespace detail template int (signbit)(T x) { typedef typename detail::fp_traits::type traits; typedef typename traits::method method; // typedef typename boost::is_floating_point::type fp_tag; typedef typename tools::promote_args_permissive::type result_type; return detail::signbit_impl(static_cast(x), method()); } template inline int sign BOOST_NO_MACRO_EXPAND(const T& z) { return (z == 0) ? 0 : (boost::math::signbit)(z) ? -1 : 1; } template typename tools::promote_args_permissive::type (changesign)(const T& x) { //!< \brief return unchanged binary pattern of x, except for change of sign bit. typedef typename detail::fp_traits::sign_change_type traits; typedef typename traits::method method; // typedef typename boost::is_floating_point::type fp_tag; typedef typename tools::promote_args_permissive::type result_type; return detail::changesign_impl(static_cast(x), method()); } template inline typename tools::promote_args_permissive::type copysign BOOST_NO_MACRO_EXPAND(const T& x, const U& y) { BOOST_MATH_STD_USING typedef typename tools::promote_args_permissive::type result_type; return (boost::math::signbit)(static_cast(x)) != (boost::math::signbit)(static_cast(y)) ? (boost::math::changesign)(static_cast(x)) : static_cast(x); } } // namespace math } // namespace boost #endif // BOOST_MATH_TOOLS_SIGN_HPP