1 // signbit.hpp
2
3 #ifndef BOOST_SPIRIT_MATH_SIGNBIT_HPP
4 #define BOOST_SPIRIT_MATH_SIGNBIT_HPP
5
6 // Copyright (c) 2006 Johan Rade
7
8 // Distributed under the Boost Software License, Version 1.0.
9 // (See accompanying file LICENSE_1_0.txt
10 // or copy at http://www.boost.org/LICENSE_1_0.txt)
11
12 #if defined(_MSC_VER)
13 #pragma once
14 #endif
15
16 #include <boost/spirit/home/support/detail/math/detail/fp_traits.hpp>
17
18 namespace boost {
19 namespace spirit {
20 namespace math {
21
22 //------------------------------------------------------------------------------
23
24 template<class T> bool (signbit)(T x)
25 {
26 typedef BOOST_DEDUCED_TYPENAME detail::fp_traits<T>::type traits;
27 traits::init();
28
29 BOOST_DEDUCED_TYPENAME traits::bits a;
30 traits::get_bits(x,a);
31 a &= traits::sign;
32 return a != 0;
33 }
34
35 //------------------------------------------------------------------------------
36
37 namespace detail {
38
copysign_impl(T x,T y)39 template<class T> T copysign_impl(T x, T y)
40 {
41 typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::type traits;
42 traits::init();
43
44 BOOST_DEDUCED_TYPENAME traits::bits a;
45 traits::get_bits(x,a);
46 a &= ~traits::sign;
47
48 BOOST_DEDUCED_TYPENAME traits::bits b;
49 traits::get_bits(y,b);
50 b &= traits::sign;
51
52 traits::set_bits(x,a|b);
53 return x;
54 }
55 }
56
57 inline float (copysign)(float x, float y) // magnitude of x and sign of y
58 {
59 return detail::copysign_impl(x,y);
60 }
61
62 inline double (copysign)(double x, double y)
63 {
64 return detail::copysign_impl(x,y);
65 }
66
67 inline long double (copysign)(long double x, long double y)
68 {
69 return detail::copysign_impl(x,y);
70 }
71
72 //------------------------------------------------------------------------------
73
T(changesign)74 template<class T> T (changesign)(T x)
75 {
76 typedef BOOST_DEDUCED_TYPENAME detail::fp_traits<T>::type traits;
77 traits::init();
78
79 BOOST_DEDUCED_TYPENAME traits::bits a;
80 traits::get_bits(x,a);
81 a ^= traits::sign;
82 traits::set_bits(x,a);
83 return x;
84 }
85
86 //------------------------------------------------------------------------------
87
88 } // namespace math
89 } // namespace spirit
90 } // namespace boost
91
92 #endif
93