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1 | // fpclassify.hpp |
2 | ||
3 | #ifndef BOOST_SPIRIT_MATH_FPCLASSIFY_HPP | |
4 | #define BOOST_SPIRIT_MATH_FPCLASSIFY_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 | /* | |
13 | The following algorithm is used: | |
14 | ||
15 | If all exponent bits, the flag bit (if there is one), | |
16 | and all mantissa bits are 0, then the number is zero. | |
17 | ||
18 | If all exponent bits and the flag bit (if there is one) are 0, | |
19 | and at least one mantissa bit is 1, then the number is subnormal. | |
20 | ||
21 | If all exponent bits are 1 and all mantissa bits are 0, | |
22 | then the number is infinity. | |
23 | ||
24 | If all exponent bits are 1 and at least one mantissa bit is 1, | |
25 | then the number is a not-a-number. | |
26 | ||
27 | Otherwise the number is normal. | |
28 | ||
29 | (Note that the binary representation of infinity | |
30 | has flag bit 0 for Motorola 68K extended double precision, | |
31 | and flag bit 1 for Intel extended double precision.) | |
32 | ||
33 | To get the bits, the four or eight most significant bytes are copied | |
34 | into an uint32_t or uint64_t and bit masks are applied. | |
35 | This covers all the exponent bits and the flag bit (if there is one), | |
36 | but not always all the mantissa bits. | |
37 | Some of the functions below have two implementations, | |
38 | depending on whether all the mantissa bits are copied or not. | |
39 | */ | |
40 | ||
41 | #if defined(_MSC_VER) | |
42 | #pragma once | |
43 | #endif | |
44 | ||
45 | #include <cmath> | |
46 | ||
47 | #ifndef FP_INFINITE | |
48 | # define FP_INFINITE 0 | |
49 | # define FP_NAN 1 | |
50 | # define FP_NORMAL 2 | |
51 | # define FP_SUBNORMAL 3 | |
52 | # define FP_ZERO 4 | |
53 | #endif | |
54 | ||
55 | #include <boost/spirit/home/support/detail/math/detail/fp_traits.hpp> | |
56 | ||
57 | namespace boost { | |
58 | namespace spirit { | |
59 | namespace math { | |
60 | ||
61 | //------------------------------------------------------------------------------ | |
62 | ||
63 | template<class T> bool (isfinite)(T x) | |
64 | { | |
65 | typedef BOOST_DEDUCED_TYPENAME detail::fp_traits<T>::type traits; | |
66 | traits::init(); | |
67 | ||
68 | BOOST_DEDUCED_TYPENAME traits::bits a; | |
69 | traits::get_bits(x,a); | |
70 | a &= traits::exponent; | |
71 | return a != traits::exponent; | |
72 | } | |
73 | ||
74 | //------------------------------------------------------------------------------ | |
75 | ||
76 | template<class T> bool (isnormal)(T x) | |
77 | { | |
78 | typedef BOOST_DEDUCED_TYPENAME detail::fp_traits<T>::type traits; | |
79 | traits::init(); | |
80 | ||
81 | BOOST_DEDUCED_TYPENAME traits::bits a; | |
82 | traits::get_bits(x,a); | |
83 | a &= traits::exponent | traits::flag; | |
84 | return (a != 0) && (a < traits::exponent); | |
85 | } | |
86 | ||
87 | //------------------------------------------------------------------------------ | |
88 | ||
89 | namespace detail { | |
90 | ||
91 | template<class T> bool isinf_impl(T x, all_bits) | |
92 | { | |
93 | typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::type traits; | |
94 | ||
95 | BOOST_DEDUCED_TYPENAME traits::bits a; | |
96 | traits::get_bits(x,a); | |
97 | a &= traits::exponent | traits::mantissa; | |
98 | return a == traits::exponent; | |
99 | } | |
100 | ||
101 | template<class T> bool isinf_impl(T x, not_all_bits) | |
102 | { | |
103 | typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::type traits; | |
104 | ||
105 | BOOST_DEDUCED_TYPENAME traits::bits a; | |
106 | traits::get_bits(x,a); | |
107 | a &= traits::exponent | traits::mantissa; | |
108 | if(a != traits::exponent) | |
109 | return false; | |
110 | ||
111 | traits::set_bits(x,0); | |
112 | return x == 0; | |
113 | } | |
114 | ||
115 | } // namespace detail | |
116 | ||
117 | template<class T> bool (isinf)(T x) | |
118 | { | |
119 | typedef BOOST_DEDUCED_TYPENAME detail::fp_traits<T>::type traits; | |
120 | traits::init(); | |
121 | return detail::isinf_impl(x, BOOST_DEDUCED_TYPENAME traits::coverage()); | |
122 | } | |
123 | ||
124 | //------------------------------------------------------------------------------ | |
125 | ||
126 | namespace detail { | |
127 | ||
128 | template<class T> bool isnan_impl(T x, all_bits) | |
129 | { | |
130 | typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::type traits; | |
131 | traits::init(); | |
132 | ||
133 | BOOST_DEDUCED_TYPENAME traits::bits a; | |
134 | traits::get_bits(x,a); | |
135 | a &= traits::exponent | traits::mantissa; | |
136 | return a > traits::exponent; | |
137 | } | |
138 | ||
139 | template<class T> bool isnan_impl(T x, not_all_bits) | |
140 | { | |
141 | typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::type traits; | |
142 | traits::init(); | |
143 | ||
144 | BOOST_DEDUCED_TYPENAME traits::bits a; | |
145 | traits::get_bits(x,a); | |
146 | ||
147 | a &= traits::exponent | traits::mantissa; | |
148 | if(a < traits::exponent) | |
149 | return false; | |
150 | ||
151 | a &= traits::mantissa; | |
152 | traits::set_bits(x,a); | |
153 | return x != 0; | |
154 | } | |
155 | ||
156 | } // namespace detail | |
157 | ||
158 | template<class T> bool (isnan)(T x) | |
159 | { | |
160 | typedef BOOST_DEDUCED_TYPENAME detail::fp_traits<T>::type traits; | |
161 | traits::init(); | |
162 | return detail::isnan_impl(x, BOOST_DEDUCED_TYPENAME traits::coverage()); | |
163 | } | |
164 | ||
165 | //------------------------------------------------------------------------------ | |
166 | ||
167 | namespace detail { | |
168 | ||
169 | template<class T> int fpclassify_impl(T x, all_bits) | |
170 | { | |
171 | typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::type traits; | |
172 | ||
173 | BOOST_DEDUCED_TYPENAME traits::bits a; | |
174 | traits::get_bits(x,a); | |
175 | a &= traits::exponent | traits::flag | traits::mantissa; | |
176 | ||
177 | if(a <= traits::mantissa) { | |
178 | if(a == 0) | |
179 | return FP_ZERO; | |
180 | else | |
181 | return FP_SUBNORMAL; | |
182 | } | |
183 | ||
184 | if(a < traits::exponent) | |
185 | return FP_NORMAL; | |
186 | ||
187 | a &= traits::mantissa; | |
188 | if(a == 0) | |
189 | return FP_INFINITE; | |
190 | ||
191 | return FP_NAN; | |
192 | } | |
193 | ||
194 | template<class T> int fpclassify_impl(T x, not_all_bits) | |
195 | { | |
196 | typedef BOOST_DEDUCED_TYPENAME fp_traits<T>::type traits; | |
197 | ||
198 | BOOST_DEDUCED_TYPENAME traits::bits a; | |
199 | traits::get_bits(x,a); | |
200 | a &= traits::exponent | traits::flag | traits::mantissa; | |
201 | ||
202 | if(a <= traits::mantissa) { | |
203 | if(x == 0) | |
204 | return FP_ZERO; | |
205 | else | |
206 | return FP_SUBNORMAL; | |
207 | } | |
208 | ||
209 | if(a < traits::exponent) | |
210 | return FP_NORMAL; | |
211 | ||
212 | a &= traits::mantissa; | |
213 | traits::set_bits(x,a); | |
214 | if(x == 0) | |
215 | return FP_INFINITE; | |
216 | ||
217 | return FP_NAN; | |
218 | } | |
219 | ||
220 | } // namespace detail | |
221 | ||
222 | template<class T> int (fpclassify)(T x) | |
223 | { | |
224 | typedef BOOST_DEDUCED_TYPENAME detail::fp_traits<T>::type traits; | |
225 | traits::init(); | |
226 | return detail::fpclassify_impl(x, BOOST_DEDUCED_TYPENAME traits::coverage()); | |
227 | } | |
228 | ||
229 | //------------------------------------------------------------------------------ | |
230 | ||
231 | } // namespace math | |
232 | } // namespace spirit | |
233 | } // namespace boost | |
234 | ||
235 | #endif |