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 |
8 | |
9 | #include <boost/config.hpp> |
10 | #if defined(BOOST_HAS_PRAGMA_ONCE) |
11 | #pragma once |
12 | #endif |
13 | |
14 | #include <boost/container_hash/detail/float_functions.hpp> |
15 | #include <boost/container_hash/detail/limits.hpp> |
16 | #include <boost/core/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(dest: &seed, src: ptr, n: 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(dest: &buffer, src: ptr, n: sizeof(std::size_t)); |
78 | hash_float_combine(seed, value: 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(dest: &buffer, src: ptr, n: length); |
87 | hash_float_combine(seed, value: 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(ptr: (char*) &v, length: 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(ptr: (char*) &v, length: 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(ptr: (char*) &v, length: 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(ptr: (char*) &v, length: 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, value: part); |
180 | } |
181 | |
182 | hash_float_combine(seed, value: 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__) && !defined(__clang__) |
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 |
272 | |