Vc  1.0.0-dev
SIMD Vector Classes for C++
const.h
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2 Copyright © 2013-2015 Matthias Kretz <kretz@kde.org>
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27 }}}*/
28 
29 #ifndef VC_COMMON_CONST_H_
30 #define VC_COMMON_CONST_H_
31 
32 #include <type_traits>
33 #include <Vc/global.h>
34 
35 namespace Vc_VERSIONED_NAMESPACE
36 {
37 namespace Detail
38 {
39 
40 template <int exponent> constexpr double exponentToFloat(std::integral_constant<bool, true>);
41 template <int exponent> constexpr double exponentToFloat(std::integral_constant<bool, false>);
42 template <> constexpr double exponentToFloat<0>(std::integral_constant<bool, true>)
43 {
44  return 1.;
45 }
46 template <> constexpr double exponentToFloat<0>(std::integral_constant<bool, false>)
47 {
48  return 1.;
49 }
50 template <> constexpr double exponentToFloat<-32>(std::integral_constant<bool, true>)
51 {
52  return 1. / (65536. * 65536.);
53 }
54 template <> constexpr double exponentToFloat<32>(std::integral_constant<bool, false>)
55 {
56  return 65536. * 65536.;
57 }
58 template <> constexpr double exponentToFloat<-64>(std::integral_constant<bool, true>)
59 {
60  return 1. / (65536. * 65536. * 65536. * 65536.);
61 }
62 template <> constexpr double exponentToFloat<64>(std::integral_constant<bool, false>)
63 {
64  return 65536. * 65536. * 65536. * 65536.;
65 }
66 template <int exponent>
67 constexpr double exponentToFloat(std::integral_constant<bool, false> negative)
68 {
69  return exponentToFloat<exponent - 1>(negative) * 2.0;
70 }
71 template <int exponent>
72 constexpr double exponentToFloat(std::integral_constant<bool, true> negative)
73 {
74  return exponentToFloat<exponent + 1>(negative) * 0.5;
75 }
76 template <int sign, unsigned long long mantissa, int exponent> constexpr double doubleConstant()
77 {
78  return (static_cast<double>((mantissa & 0x000fffffffffffffull) | 0x0010000000000000ull) /
79  0x0010000000000000ull) *
80  exponentToFloat<exponent>(std::integral_constant<bool, (exponent < 0)>()) * sign;
81 }
82 template <int sign, unsigned int mantissa, int exponent> constexpr float floatConstant()
83 {
84  return (static_cast<float>((mantissa & 0x007fffffu) | 0x00800000u) / 0x00800000u) *
85  static_cast<float>(
86  exponentToFloat<exponent>(std::integral_constant<bool, (exponent < 0)>())) *
87  sign;
88 }
89 
90 } // namespace Detail
91 } // namespace Vc
92 
93 #endif // VC_COMMON_CONST_H_