-\r
-// Copyright 2005-2009 Daniel James.\r
-// Distributed under the Boost Software License, Version 1.0. (See accompanying\r
-// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)\r
-\r
-// A general purpose hash function for non-zero floating point values.\r
-\r
-#if !defined(BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_GENERIC_HEADER)\r
-#define BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_GENERIC_HEADER\r
-\r
-#include <boost/functional/hash/detail/float_functions.hpp>\r
-#include <boost/integer/static_log2.hpp>\r
-#include <boost/functional/hash/detail/limits.hpp>\r
-\r
-#if defined(_MSC_VER) && (_MSC_VER >= 1020)\r
-# pragma once\r
-#endif\r
-\r
-#if defined(BOOST_MSVC)\r
-#pragma warning(push)\r
-#if BOOST_MSVC >= 1400\r
-#pragma warning(disable:6294) // Ill-defined for-loop: initial condition does\r
- // not satisfy test. Loop body not executed \r
-#endif\r
-#endif\r
-\r
-namespace boost\r
-{\r
- namespace hash_detail\r
- {\r
- inline void hash_float_combine(std::size_t& seed, std::size_t value)\r
- {\r
- seed ^= value + (seed<<6) + (seed>>2);\r
- }\r
-\r
- template <class T>\r
- inline std::size_t float_hash_impl2(T v)\r
- {\r
- boost::hash_detail::call_frexp<T> frexp;\r
- boost::hash_detail::call_ldexp<T> ldexp;\r
- \r
- int exp = 0;\r
-\r
- v = frexp(v, &exp);\r
-\r
- // A postive value is easier to hash, so combine the\r
- // sign with the exponent and use the absolute value.\r
- if(v < 0) {\r
- v = -v;\r
- exp += limits<T>::max_exponent -\r
- limits<T>::min_exponent;\r
- }\r
-\r
- // The result of frexp is always between 0.5 and 1, so its\r
- // top bit will always be 1. Subtract by 0.5 to remove that.\r
- v -= T(0.5);\r
- v = ldexp(v, limits<std::size_t>::digits + 1);\r
- std::size_t seed = static_cast<std::size_t>(v);\r
- v -= seed;\r
-\r
- // ceiling(digits(T) * log2(radix(T))/ digits(size_t)) - 1;\r
- std::size_t const length\r
- = (limits<T>::digits *\r
- boost::static_log2<limits<T>::radix>::value - 1)\r
- / limits<std::size_t>::digits;\r
-\r
- for(std::size_t i = 0; i != length; ++i)\r
- {\r
- v = ldexp(v, limits<std::size_t>::digits);\r
- std::size_t part = static_cast<std::size_t>(v);\r
- v -= part;\r
- hash_float_combine(seed, part);\r
- }\r
-\r
- hash_float_combine(seed, exp);\r
-\r
- return seed;\r
- }\r
-\r
- template <class T>\r
- inline std::size_t float_hash_impl(T v)\r
- {\r
- typedef BOOST_DEDUCED_TYPENAME select_hash_type<T>::type type;\r
- return float_hash_impl2(static_cast<type>(v));\r
- }\r
- }\r
-}\r
-\r
-#if defined(BOOST_MSVC)\r
-#pragma warning(pop)\r
-#endif\r
-\r
-#endif\r
+
+// Copyright 2005-2009 Daniel James.
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// A general purpose hash function for non-zero floating point values.
+
+#if !defined(BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_GENERIC_HEADER)
+#define BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_GENERIC_HEADER
+
+#include <boost/functional/hash/detail/float_functions.hpp>
+#include <boost/integer/static_log2.hpp>
+#include <boost/functional/hash/detail/limits.hpp>
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+#if defined(BOOST_MSVC)
+#pragma warning(push)
+#if BOOST_MSVC >= 1400
+#pragma warning(disable:6294) // Ill-defined for-loop: initial condition does
+ // not satisfy test. Loop body not executed
+#endif
+#endif
+
+namespace boost
+{
+ namespace hash_detail
+ {
+ inline void hash_float_combine(std::size_t& seed, std::size_t value)
+ {
+ seed ^= value + (seed<<6) + (seed>>2);
+ }
+
+ template <class T>
+ inline std::size_t float_hash_impl2(T v)
+ {
+ boost::hash_detail::call_frexp<T> frexp;
+ boost::hash_detail::call_ldexp<T> ldexp;
+
+ int exp = 0;
+
+ v = frexp(v, &exp);
+
+ // A postive value is easier to hash, so combine the
+ // sign with the exponent and use the absolute value.
+ if(v < 0) {
+ v = -v;
+ exp += limits<T>::max_exponent -
+ limits<T>::min_exponent;
+ }
+
+ // The result of frexp is always between 0.5 and 1, so its
+ // top bit will always be 1. Subtract by 0.5 to remove that.
+ v -= T(0.5);
+ v = ldexp(v, limits<std::size_t>::digits + 1);
+ std::size_t seed = static_cast<std::size_t>(v);
+ v -= seed;
+
+ // ceiling(digits(T) * log2(radix(T))/ digits(size_t)) - 1;
+ std::size_t const length
+ = (limits<T>::digits *
+ boost::static_log2<limits<T>::radix>::value - 1)
+ / limits<std::size_t>::digits;
+
+ for(std::size_t i = 0; i != length; ++i)
+ {
+ v = ldexp(v, limits<std::size_t>::digits);
+ std::size_t part = static_cast<std::size_t>(v);
+ v -= part;
+ hash_float_combine(seed, part);
+ }
+
+ hash_float_combine(seed, exp);
+
+ return seed;
+ }
+
+ template <class T>
+ inline std::size_t float_hash_impl(T v)
+ {
+ typedef BOOST_DEDUCED_TYPENAME select_hash_type<T>::type type;
+ return float_hash_impl2(static_cast<type>(v));
+ }
+ }
+}
+
+#if defined(BOOST_MSVC)
+#pragma warning(pop)
+#endif
+
+#endif
projects / features.git / blobdiff