williamr@2: 
williamr@2: //  Copyright Daniel James 2005-2006. Use, modification, and distribution are
williamr@2: //  subject to the Boost Software License, Version 1.0. (See accompanying
williamr@2: //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
williamr@2: 
williamr@2: //  Based on Peter Dimov's proposal
williamr@2: //  http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1756.pdf
williamr@2: //  issue 6.18. 
williamr@2: 
williamr@2: #if !defined(BOOST_FUNCTIONAL_DETAIL_HASH_FLOAT_HEADER)
williamr@2: #define BOOST_FUNCTIONAL_DETAIL_HASH_FLOAT_HEADER
williamr@2: 
williamr@2: #if defined(_MSC_VER) && (_MSC_VER >= 1020)
williamr@2: # pragma once
williamr@2: #endif
williamr@2: 
williamr@2: #include <boost/functional/detail/float_functions.hpp>
williamr@2: #include <boost/limits.hpp>
williamr@2: #include <boost/assert.hpp>
williamr@2: #include <errno.h>
williamr@2: 
williamr@2: // Don't use fpclassify or _fpclass for stlport.
williamr@2: #if !defined(__SGI_STL_PORT) && !defined(_STLPORT_VERSION)
williamr@2: #  if defined(__GLIBCPP__) || defined(__GLIBCXX__)
williamr@2: // GNU libstdc++ 3
williamr@2: #    if (defined(__USE_ISOC99) || defined(_GLIBCXX_USE_C99_MATH)) && \
williamr@2:         !(defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__))
williamr@2: #      define BOOST_HASH_USE_FPCLASSIFY
williamr@2: #    endif
williamr@2: #  elif (defined(_YVALS) && !defined(__IBMCPP__)) || defined(_CPPLIB_VER)
williamr@2: // Dinkumware Library, on Visual C++ 
williamr@2: #    if defined(BOOST_MSVC)
williamr@2: #      define BOOST_HASH_USE_FPCLASS
williamr@2: #    endif
williamr@2: #  endif
williamr@2: #endif
williamr@2: 
williamr@2: namespace boost
williamr@2: {
williamr@2:     namespace hash_detail
williamr@2:     {
williamr@2:         inline void hash_float_combine(std::size_t& seed, std::size_t value)
williamr@2:         {
williamr@2:             seed ^= value + (seed<<6) + (seed>>2);
williamr@2:         }
williamr@2: 
williamr@2:         template <class T>
williamr@2:         inline std::size_t float_hash_impl(T v)
williamr@2:         {
williamr@2:             int exp = 0;
williamr@2:             errno = 0;
williamr@2:             v = boost::hash_detail::call_frexp(v, &exp);
williamr@2:             if(errno) return 0;
williamr@2: 
williamr@2:             std::size_t seed = 0;
williamr@2: 
williamr@2:             std::size_t const length
williamr@2:                 = (std::numeric_limits<T>::digits +
williamr@2:                         std::numeric_limits<int>::digits - 1)
williamr@2:                 / std::numeric_limits<int>::digits;
williamr@2: 
williamr@2:             for(std::size_t i = 0; i < length; ++i)
williamr@2:             {
williamr@2:                 v = boost::hash_detail::call_ldexp(v, std::numeric_limits<int>::digits);
williamr@2:                 int const part = static_cast<int>(v);
williamr@2:                 v -= part;
williamr@2:                 hash_float_combine(seed, part);
williamr@2:             }
williamr@2: 
williamr@2:             hash_float_combine(seed, exp);
williamr@2: 
williamr@2:             return seed;
williamr@2:         }
williamr@2: 
williamr@2:         template <class T>
williamr@2:         inline std::size_t float_hash_value(T v)
williamr@2:         {
williamr@2: #if defined(BOOST_HASH_USE_FPCLASSIFY)
williamr@2:             using namespace std;
williamr@2:             switch (fpclassify(v)) {
williamr@2:             case FP_ZERO:
williamr@2:                 return 0;
williamr@2:             case FP_INFINITE:
williamr@2:                 return (std::size_t)(v > 0 ? -1 : -2);
williamr@2:             case FP_NAN:
williamr@2:                 return (std::size_t)(-3);
williamr@2:             case FP_NORMAL:
williamr@2:             case FP_SUBNORMAL:
williamr@2:                 return float_hash_impl(v);
williamr@2:             default:
williamr@2:                 BOOST_ASSERT(0);
williamr@2:                 return 0;
williamr@2:             }
williamr@2: #elif defined(BOOST_HASH_USE_FPCLASS)
williamr@2:             switch(_fpclass(v)) {
williamr@2:             case _FPCLASS_NZ:
williamr@2:             case _FPCLASS_PZ:
williamr@2:                 return 0;
williamr@2:             case _FPCLASS_PINF:
williamr@2:                 return (std::size_t)(-1);
williamr@2:             case _FPCLASS_NINF:
williamr@2:                 return (std::size_t)(-2);
williamr@2:             case _FPCLASS_SNAN:
williamr@2:             case _FPCLASS_QNAN:
williamr@2:                 return (std::size_t)(-3);
williamr@2:             case _FPCLASS_NN:
williamr@2:             case _FPCLASS_ND:
williamr@2:                 return float_hash_impl(v);
williamr@2:             case _FPCLASS_PD:
williamr@2:             case _FPCLASS_PN:
williamr@2:                 return float_hash_impl(v);
williamr@2:             default:
williamr@2:                 BOOST_ASSERT(0);
williamr@2:                 return 0;
williamr@2:             }
williamr@2: #else
williamr@2:             return float_hash_impl(v);
williamr@2: #endif
williamr@2:         }
williamr@2:     }
williamr@2: }
williamr@2: 
williamr@2: #endif