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1 | |
2 | // Copyright 2005-2012 Daniel James. | |
3 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
4 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
5 | ||
6 | #if !defined(BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_HEADER) | |
7 | #define BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_HEADER | |
8 | ||
9 | #include <boost/config.hpp> | |
10 | #if defined(BOOST_HAS_PRAGMA_ONCE) | |
11 | #pragma once | |
12 | #endif | |
13 | ||
14 | #include <boost/functional/hash/detail/float_functions.hpp> | |
15 | #include <boost/functional/hash/detail/limits.hpp> | |
16 | #include <boost/utility/enable_if.hpp> | |
17 | #include <boost/integer/static_log2.hpp> | |
18 | #include <boost/cstdint.hpp> | |
19 | #include <boost/assert.hpp> | |
20 | #include <boost/limits.hpp> | |
21 | #include <cstring> | |
22 | ||
23 | #if defined(BOOST_MSVC) | |
24 | #pragma warning(push) | |
25 | #if BOOST_MSVC >= 1400 | |
26 | #pragma warning(disable:6294) // Ill-defined for-loop: initial condition does | |
27 | // not satisfy test. Loop body not executed | |
28 | #endif | |
29 | #endif | |
30 | ||
31 | // Can we use fpclassify? | |
32 | ||
33 | // STLport | |
34 | #if defined(__SGI_STL_PORT) || defined(_STLPORT_VERSION) | |
35 | #define BOOST_HASH_USE_FPCLASSIFY 0 | |
36 | ||
37 | // GNU libstdc++ 3 | |
38 | #elif defined(__GLIBCPP__) || defined(__GLIBCXX__) | |
39 | # if (defined(__USE_ISOC99) || defined(_GLIBCXX_USE_C99_MATH)) && \ | |
40 | !(defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__)) | |
41 | # define BOOST_HASH_USE_FPCLASSIFY 1 | |
42 | # else | |
43 | # define BOOST_HASH_USE_FPCLASSIFY 0 | |
44 | # endif | |
45 | ||
46 | // Everything else | |
47 | #else | |
48 | # define BOOST_HASH_USE_FPCLASSIFY 0 | |
49 | #endif | |
50 | ||
51 | namespace boost | |
52 | { | |
53 | namespace hash_detail | |
54 | { | |
55 | inline void hash_float_combine(std::size_t& seed, std::size_t value) | |
56 | { | |
57 | seed ^= value + (seed<<6) + (seed>>2); | |
58 | } | |
59 | ||
60 | //////////////////////////////////////////////////////////////////////// | |
61 | // Binary hash function | |
62 | // | |
63 | // Only used for floats with known iec559 floats, and certain values in | |
64 | // numeric_limits | |
65 | ||
66 | inline std::size_t hash_binary(char* ptr, std::size_t length) | |
67 | { | |
68 | std::size_t seed = 0; | |
69 | ||
70 | if (length >= sizeof(std::size_t)) { | |
71 | std::memcpy(&seed, ptr, sizeof(std::size_t)); | |
72 | length -= sizeof(std::size_t); | |
73 | ptr += sizeof(std::size_t); | |
74 | ||
75 | while(length >= sizeof(std::size_t)) { | |
76 | std::size_t buffer = 0; | |
77 | std::memcpy(&buffer, ptr, sizeof(std::size_t)); | |
78 | hash_float_combine(seed, buffer); | |
79 | length -= sizeof(std::size_t); | |
80 | ptr += sizeof(std::size_t); | |
81 | } | |
82 | } | |
83 | ||
84 | if (length > 0) { | |
85 | std::size_t buffer = 0; | |
86 | std::memcpy(&buffer, ptr, length); | |
87 | hash_float_combine(seed, buffer); | |
88 | } | |
89 | ||
90 | return seed; | |
91 | } | |
92 | ||
93 | template <typename Float, unsigned digits, unsigned max_exponent> | |
94 | struct enable_binary_hash | |
95 | { | |
96 | BOOST_STATIC_CONSTANT(bool, value = | |
97 | std::numeric_limits<Float>::is_iec559 && | |
98 | std::numeric_limits<Float>::digits == digits && | |
99 | std::numeric_limits<Float>::radix == 2 && | |
100 | std::numeric_limits<Float>::max_exponent == max_exponent); | |
101 | }; | |
102 | ||
103 | template <typename Float> | |
104 | inline std::size_t float_hash_impl(Float v, | |
105 | BOOST_DEDUCED_TYPENAME boost::enable_if_c< | |
106 | enable_binary_hash<Float, 24, 128>::value, | |
107 | std::size_t>::type) | |
108 | { | |
109 | return hash_binary((char*) &v, 4); | |
110 | } | |
111 | ||
112 | ||
113 | template <typename Float> | |
114 | inline std::size_t float_hash_impl(Float v, | |
115 | BOOST_DEDUCED_TYPENAME boost::enable_if_c< | |
116 | enable_binary_hash<Float, 53, 1024>::value, | |
117 | std::size_t>::type) | |
118 | { | |
119 | return hash_binary((char*) &v, 8); | |
120 | } | |
121 | ||
122 | template <typename Float> | |
123 | inline std::size_t float_hash_impl(Float v, | |
124 | BOOST_DEDUCED_TYPENAME boost::enable_if_c< | |
125 | enable_binary_hash<Float, 64, 16384>::value, | |
126 | std::size_t>::type) | |
127 | { | |
128 | return hash_binary((char*) &v, 10); | |
129 | } | |
130 | ||
131 | template <typename Float> | |
132 | inline std::size_t float_hash_impl(Float v, | |
133 | BOOST_DEDUCED_TYPENAME boost::enable_if_c< | |
134 | enable_binary_hash<Float, 113, 16384>::value, | |
135 | std::size_t>::type) | |
136 | { | |
137 | return hash_binary((char*) &v, 16); | |
138 | } | |
139 | ||
140 | //////////////////////////////////////////////////////////////////////// | |
141 | // Portable hash function | |
142 | // | |
143 | // Used as a fallback when the binary hash function isn't supported. | |
144 | ||
145 | template <class T> | |
146 | inline std::size_t float_hash_impl2(T v) | |
147 | { | |
148 | boost::hash_detail::call_frexp<T> frexp; | |
149 | boost::hash_detail::call_ldexp<T> ldexp; | |
150 | ||
151 | int exp = 0; | |
152 | ||
153 | v = frexp(v, &exp); | |
154 | ||
155 | // A postive value is easier to hash, so combine the | |
156 | // sign with the exponent and use the absolute value. | |
157 | if(v < 0) { | |
158 | v = -v; | |
159 | exp += limits<T>::max_exponent - | |
160 | limits<T>::min_exponent; | |
161 | } | |
162 | ||
163 | v = ldexp(v, limits<std::size_t>::digits); | |
164 | std::size_t seed = static_cast<std::size_t>(v); | |
165 | v -= static_cast<T>(seed); | |
166 | ||
167 | // ceiling(digits(T) * log2(radix(T))/ digits(size_t)) - 1; | |
168 | std::size_t const length | |
169 | = (limits<T>::digits * | |
170 | boost::static_log2<limits<T>::radix>::value | |
171 | + limits<std::size_t>::digits - 1) | |
172 | / limits<std::size_t>::digits; | |
173 | ||
174 | for(std::size_t i = 0; i != length; ++i) | |
175 | { | |
176 | v = ldexp(v, limits<std::size_t>::digits); | |
177 | std::size_t part = static_cast<std::size_t>(v); | |
178 | v -= static_cast<T>(part); | |
179 | hash_float_combine(seed, part); | |
180 | } | |
181 | ||
182 | hash_float_combine(seed, static_cast<std::size_t>(exp)); | |
183 | ||
184 | return seed; | |
185 | } | |
186 | ||
187 | #if !defined(BOOST_HASH_DETAIL_TEST_WITHOUT_GENERIC) | |
188 | template <class T> | |
189 | inline std::size_t float_hash_impl(T v, ...) | |
190 | { | |
191 | typedef BOOST_DEDUCED_TYPENAME select_hash_type<T>::type type; | |
192 | return float_hash_impl2(static_cast<type>(v)); | |
193 | } | |
194 | #endif | |
195 | } | |
196 | } | |
197 | ||
198 | #if BOOST_HASH_USE_FPCLASSIFY | |
199 | ||
200 | #include <boost/config/no_tr1/cmath.hpp> | |
201 | ||
202 | namespace boost | |
203 | { | |
204 | namespace hash_detail | |
205 | { | |
206 | template <class T> | |
207 | inline std::size_t float_hash_value(T v) | |
208 | { | |
209 | #if defined(fpclassify) | |
210 | switch (fpclassify(v)) | |
211 | #elif BOOST_HASH_CONFORMANT_FLOATS | |
212 | switch (std::fpclassify(v)) | |
213 | #else | |
214 | using namespace std; | |
215 | switch (fpclassify(v)) | |
216 | #endif | |
217 | { | |
218 | case FP_ZERO: | |
219 | return 0; | |
220 | case FP_INFINITE: | |
221 | return (std::size_t)(v > 0 ? -1 : -2); | |
222 | case FP_NAN: | |
223 | return (std::size_t)(-3); | |
224 | case FP_NORMAL: | |
225 | case FP_SUBNORMAL: | |
226 | return float_hash_impl(v, 0); | |
227 | default: | |
228 | BOOST_ASSERT(0); | |
229 | return 0; | |
230 | } | |
231 | } | |
232 | } | |
233 | } | |
234 | ||
235 | #else // !BOOST_HASH_USE_FPCLASSIFY | |
236 | ||
237 | namespace boost | |
238 | { | |
239 | namespace hash_detail | |
240 | { | |
241 | template <class T> | |
242 | inline bool is_zero(T v) | |
243 | { | |
244 | #if !defined(__GNUC__) | |
245 | return v == 0; | |
246 | #else | |
247 | // GCC's '-Wfloat-equal' will complain about comparing | |
248 | // v to 0, but because it disables warnings for system | |
249 | // headers it won't complain if you use std::equal_to to | |
250 | // compare with 0. Resulting in this silliness: | |
251 | return std::equal_to<T>()(v, 0); | |
252 | #endif | |
253 | } | |
254 | ||
255 | template <class T> | |
256 | inline std::size_t float_hash_value(T v) | |
257 | { | |
258 | return boost::hash_detail::is_zero(v) ? 0 : float_hash_impl(v, 0); | |
259 | } | |
260 | } | |
261 | } | |
262 | ||
263 | #endif // BOOST_HASH_USE_FPCLASSIFY | |
264 | ||
265 | #undef BOOST_HASH_USE_FPCLASSIFY | |
266 | ||
267 | #if defined(BOOST_MSVC) | |
268 | #pragma warning(pop) | |
269 | #endif | |
270 | ||
271 | #endif |