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On Cygwin use a binary based hash function for floating point numbers, as

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Cygwin doesn't have decent floating point functions for long doubles.


[SVN r39694]
This commit is contained in:
Daniel James
2007-10-05 09:46:22 +00:00
parent 3b30bda727
commit ee28cdbcd5
1 changed files with 54 additions and 14 deletions
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68
include/boost/functional/detail/hash_float.hpp
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@@ -15,23 +15,35 @@
#endif
#include <boost/functional/detail/float_functions.hpp>
#include <boost/cstdint.hpp>
#include <boost/limits.hpp>
#include <boost/assert.hpp>
// Don't use fpclassify or _fpclass for stlport.
#if !defined(__SGI_STL_PORT) && !defined(_STLPORT_VERSION)
# if defined(__GLIBCPP__) || defined(__GLIBCXX__)
// GNU libstdc++ 3
# if (defined(__USE_ISOC99) || defined(_GLIBCXX_USE_C99_MATH)) && \
!(defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__))
# define BOOST_HASH_USE_FPCLASSIFY
# endif
# elif (defined(_YVALS) && !defined(__IBMCPP__)) || defined(_CPPLIB_VER)
// Dinkumware Library, on Visual C++
# if defined(BOOST_MSVC)
# define BOOST_HASH_USE_FPCLASS
# endif
// Select implementation for the current platform.
// Cygwn
#if defined(__CYGWIN__)
# if defined(__i386__) || defined(_M_IX86)
# define BOOST_HASH_USE_x86_BINARY_HASH
# endif
// STLport
#elif defined(__SGI_STL_PORT) || defined(_STLPORT_VERSION)
// _fpclass and fpclassify aren't good enough on STLport.
// GNU libstdc++ 3
#elif defined(__GLIBCPP__) || defined(__GLIBCXX__)
# if (defined(__USE_ISOC99) || defined(_GLIBCXX_USE_C99_MATH)) && \
!(defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__))
# define BOOST_HASH_USE_FPCLASSIFY
# endif
// Dinkumware Library, on Visual C++
#elif (defined(_YVALS) && !defined(__IBMCPP__)) || defined(_CPPLIB_VER)
# if defined(BOOST_MSVC)
# define BOOST_HASH_USE_FPCLASS
# endif
#endif
namespace boost
@@ -43,6 +55,33 @@ namespace boost
seed ^= value + (seed<<6) + (seed>>2);
}
// A simple, non-portable hash algorithm for x86.
#if defined(BOOST_HASH_USE_x86_BINARY_HASH)
inline std::size_t float_hash_impl(float v)
{
boost::uint32_t* ptr = (boost::uint32_t*)&v;
std::size_t seed = *ptr;
return seed;
}
inline std::size_t float_hash_impl(double v)
{
boost::uint32_t* ptr = (boost::uint32_t*)&v;
std::size_t seed = *ptr++;
hash_float_combine(seed, *ptr);
return seed;
}
inline std::size_t float_hash_impl(long double v)
{
boost::uint32_t* ptr = (boost::uint32_t*)&v;
std::size_t seed = *ptr++;
hash_float_combine(seed, *ptr++);
hash_float_combine(seed, *(boost::uint16_t*)ptr);
return seed;
}
#else
template <class T>
inline std::size_t float_hash_impl(T v)
{
@@ -68,6 +107,7 @@ namespace boost
return seed;
}
#endif
template <class T>
inline std::size_t float_hash_value(T v)
@@ -111,7 +151,7 @@ namespace boost
return 0;
}
#else
return float_hash_impl(v);
return v == 0 ? 0 : float_hash_impl(v);
#endif
}
}