Jeff Thompson | 86b6d64 | 2013-10-17 15:01:56 -0700 | [diff] [blame] | 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(NDNBOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_HEADER) |
| 7 | #define NDNBOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_HEADER |
| 8 | |
| 9 | #if defined(_MSC_VER) && (_MSC_VER >= 1020) |
| 10 | # pragma once |
| 11 | #endif |
| 12 | |
| 13 | #include <ndnboost/config.hpp> |
| 14 | #include <ndnboost/functional/hash/detail/float_functions.hpp> |
| 15 | #include <ndnboost/functional/hash/detail/limits.hpp> |
| 16 | #include <ndnboost/utility/enable_if.hpp> |
| 17 | #include <ndnboost/integer/static_log2.hpp> |
| 18 | #include <ndnboost/cstdint.hpp> |
| 19 | #include <ndnboost/assert.hpp> |
| 20 | #include <ndnboost/limits.hpp> |
| 21 | #include <cstring> |
| 22 | |
| 23 | #if defined(NDNBOOST_MSVC) |
| 24 | #pragma warning(push) |
| 25 | #if NDNBOOST_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 NDNBOOST_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 NDNBOOST_HASH_USE_FPCLASSIFY 1 |
| 42 | # else |
| 43 | # define NDNBOOST_HASH_USE_FPCLASSIFY 0 |
| 44 | # endif |
| 45 | |
| 46 | // Everything else |
| 47 | #else |
| 48 | # define NDNBOOST_HASH_USE_FPCLASSIFY 0 |
| 49 | #endif |
| 50 | |
| 51 | namespace ndnboost |
| 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 | seed = *(std::size_t*) ptr; |
| 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> |
| 94 | inline std::size_t float_hash_impl(Float v, |
| 95 | NDNBOOST_DEDUCED_TYPENAME ndnboost::enable_if_c< |
| 96 | std::numeric_limits<Float>::is_iec559 && |
| 97 | std::numeric_limits<Float>::digits == 24 && |
| 98 | std::numeric_limits<Float>::radix == 2 && |
| 99 | std::numeric_limits<Float>::max_exponent == 128, |
| 100 | int>::type |
| 101 | ) |
| 102 | { |
| 103 | return hash_binary((char*) &v, 4); |
| 104 | } |
| 105 | |
| 106 | |
| 107 | template <typename Float> |
| 108 | inline std::size_t float_hash_impl(Float v, |
| 109 | NDNBOOST_DEDUCED_TYPENAME ndnboost::enable_if_c< |
| 110 | std::numeric_limits<Float>::is_iec559 && |
| 111 | std::numeric_limits<Float>::digits == 53 && |
| 112 | std::numeric_limits<Float>::radix == 2 && |
| 113 | std::numeric_limits<Float>::max_exponent == 1024, |
| 114 | int>::type |
| 115 | ) |
| 116 | { |
| 117 | return hash_binary((char*) &v, 8); |
| 118 | } |
| 119 | |
| 120 | template <typename Float> |
| 121 | inline std::size_t float_hash_impl(Float v, |
| 122 | NDNBOOST_DEDUCED_TYPENAME ndnboost::enable_if_c< |
| 123 | std::numeric_limits<Float>::is_iec559 && |
| 124 | std::numeric_limits<Float>::digits == 64 && |
| 125 | std::numeric_limits<Float>::radix == 2 && |
| 126 | std::numeric_limits<Float>::max_exponent == 16384, |
| 127 | int>::type |
| 128 | ) |
| 129 | { |
| 130 | return hash_binary((char*) &v, 10); |
| 131 | } |
| 132 | |
| 133 | template <typename Float> |
| 134 | inline std::size_t float_hash_impl(Float v, |
| 135 | NDNBOOST_DEDUCED_TYPENAME ndnboost::enable_if_c< |
| 136 | std::numeric_limits<Float>::is_iec559 && |
| 137 | std::numeric_limits<Float>::digits == 113 && |
| 138 | std::numeric_limits<Float>::radix == 2 && |
| 139 | std::numeric_limits<Float>::max_exponent == 16384, |
| 140 | int>::type |
| 141 | ) |
| 142 | { |
| 143 | return hash_binary((char*) &v, 16); |
| 144 | } |
| 145 | |
| 146 | //////////////////////////////////////////////////////////////////////// |
| 147 | // Portable hash function |
| 148 | // |
| 149 | // Used as a fallback when the binary hash function isn't supported. |
| 150 | |
| 151 | template <class T> |
| 152 | inline std::size_t float_hash_impl2(T v) |
| 153 | { |
| 154 | ndnboost::hash_detail::call_frexp<T> frexp; |
| 155 | ndnboost::hash_detail::call_ldexp<T> ldexp; |
| 156 | |
| 157 | int exp = 0; |
| 158 | |
| 159 | v = frexp(v, &exp); |
| 160 | |
| 161 | // A postive value is easier to hash, so combine the |
| 162 | // sign with the exponent and use the absolute value. |
| 163 | if(v < 0) { |
| 164 | v = -v; |
| 165 | exp += limits<T>::max_exponent - |
| 166 | limits<T>::min_exponent; |
| 167 | } |
| 168 | |
| 169 | v = ldexp(v, limits<std::size_t>::digits); |
| 170 | std::size_t seed = static_cast<std::size_t>(v); |
| 171 | v -= static_cast<T>(seed); |
| 172 | |
| 173 | // ceiling(digits(T) * log2(radix(T))/ digits(size_t)) - 1; |
| 174 | std::size_t const length |
| 175 | = (limits<T>::digits * |
| 176 | ndnboost::static_log2<limits<T>::radix>::value |
| 177 | + limits<std::size_t>::digits - 1) |
| 178 | / limits<std::size_t>::digits; |
| 179 | |
| 180 | for(std::size_t i = 0; i != length; ++i) |
| 181 | { |
| 182 | v = ldexp(v, limits<std::size_t>::digits); |
| 183 | std::size_t part = static_cast<std::size_t>(v); |
| 184 | v -= static_cast<T>(part); |
| 185 | hash_float_combine(seed, part); |
| 186 | } |
| 187 | |
| 188 | hash_float_combine(seed, exp); |
| 189 | |
| 190 | return seed; |
| 191 | } |
| 192 | |
| 193 | #if !defined(NDNBOOST_HASH_DETAIL_TEST_WITHOUT_GENERIC) |
| 194 | template <class T> |
| 195 | inline std::size_t float_hash_impl(T v, ...) |
| 196 | { |
| 197 | typedef NDNBOOST_DEDUCED_TYPENAME select_hash_type<T>::type type; |
| 198 | return float_hash_impl2(static_cast<type>(v)); |
| 199 | } |
| 200 | #endif |
| 201 | } |
| 202 | } |
| 203 | |
| 204 | #if NDNBOOST_HASH_USE_FPCLASSIFY |
| 205 | |
| 206 | #include <ndnboost/config/no_tr1/cmath.hpp> |
| 207 | |
| 208 | namespace ndnboost |
| 209 | { |
| 210 | namespace hash_detail |
| 211 | { |
| 212 | template <class T> |
| 213 | inline std::size_t float_hash_value(T v) |
| 214 | { |
| 215 | #if defined(fpclassify) |
| 216 | switch (fpclassify(v)) |
| 217 | #elif NDNBOOST_HASH_CONFORMANT_FLOATS |
| 218 | switch (std::fpclassify(v)) |
| 219 | #else |
| 220 | using namespace std; |
| 221 | switch (fpclassify(v)) |
| 222 | #endif |
| 223 | { |
| 224 | case FP_ZERO: |
| 225 | return 0; |
| 226 | case FP_INFINITE: |
| 227 | return (std::size_t)(v > 0 ? -1 : -2); |
| 228 | case FP_NAN: |
| 229 | return (std::size_t)(-3); |
| 230 | case FP_NORMAL: |
| 231 | case FP_SUBNORMAL: |
| 232 | return float_hash_impl(v, 0); |
| 233 | default: |
| 234 | NDNBOOST_ASSERT(0); |
| 235 | return 0; |
| 236 | } |
| 237 | } |
| 238 | } |
| 239 | } |
| 240 | |
| 241 | #else // !NDNBOOST_HASH_USE_FPCLASSIFY |
| 242 | |
| 243 | namespace ndnboost |
| 244 | { |
| 245 | namespace hash_detail |
| 246 | { |
| 247 | template <class T> |
| 248 | inline bool is_zero(T v) |
| 249 | { |
| 250 | #if !defined(__GNUC__) |
| 251 | return v == 0; |
| 252 | #else |
| 253 | // GCC's '-Wfloat-equal' will complain about comparing |
| 254 | // v to 0, but because it disables warnings for system |
| 255 | // headers it won't complain if you use std::equal_to to |
| 256 | // compare with 0. Resulting in this silliness: |
| 257 | return std::equal_to<T>()(v, 0); |
| 258 | #endif |
| 259 | } |
| 260 | |
| 261 | template <class T> |
| 262 | inline std::size_t float_hash_value(T v) |
| 263 | { |
| 264 | return ndnboost::hash_detail::is_zero(v) ? 0 : float_hash_impl(v, 0); |
| 265 | } |
| 266 | } |
| 267 | } |
| 268 | |
| 269 | #endif // NDNBOOST_HASH_USE_FPCLASSIFY |
| 270 | |
| 271 | #undef NDNBOOST_HASH_USE_FPCLASSIFY |
| 272 | |
| 273 | #if defined(NDNBOOST_MSVC) |
| 274 | #pragma warning(pop) |
| 275 | #endif |
| 276 | |
| 277 | #endif |