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Use fpclassify/_fpclass for the hash function on compilers where I

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know it's available.


[SVN r32782]
This commit is contained in:
Daniel James
2006-02-09 19:11:09 +00:00
parent a5844bc9bf
commit 2dcf38a04a
1 changed files with 56 additions and 2 deletions
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58
include/boost/functional/detail/hash_float.hpp
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@@ -16,8 +16,16 @@
#endif
#include <boost/functional/detail/float_functions.hpp>
#include <errno.h>
#include <boost/limits.hpp>
#include <boost/assert.hpp>
#include <errno.h>
#if defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
# define BOOST_HASH_USE_FPCLASS
#elif (defined(__GLIBCPP__) || defined(__GLIBCXX__)) \
&& (defined(__USE_ISOC99) || defined(_GLIBCXX_USE_C99_MATH))
# define BOOST_HASH_USE_FPCLASSIFY
#endif
namespace boost
{
@@ -29,7 +37,7 @@ namespace boost
}
template <class T>
inline std::size_t float_hash_value(T v)
inline std::size_t float_hash_impl(T v)
{
int exp = 0;
errno = 0;
@@ -55,6 +63,52 @@ namespace boost
return seed;
}
template <class T>
inline std::size_t float_hash_value(T v)
{
#if defined(BOOST_HASH_USE_FPCLASSIFY)
using namespace std;
switch (fpclassify(v)) {
case FP_ZERO:
return 0;
case FP_INFINITE:
return (std::size_t)(v > 0 ? -1 : -2);
case FP_NAN:
return (std::size_t)(-3);
case FP_NORMAL:
case FP_SUBNORMAL:
return float_hash_impl(v);
default:
BOOST_ASSERT(0);
return 0;
}
#elif defined(BOOST_HASH_USE_FPCLASS)
switch(_fpclass(v)) {
case _FPCLASS_NZ:
case _FPCLASS_PZ:
return 0;
case _FPCLASS_PINF:
return (std::size_t)(-1);
case _FPCLASS_NINF:
return (std::size_t)(-2);
case _FPCLASS_SNAN:
case _FPCLASS_QNAN:
return (std::size_t)(-3);
case _FPCLASS_NN:
case _FPCLASS_ND:
return float_hash_impl(v);
case _FPCLASS_PD:
case _FPCLASS_PN:
return float_hash_impl(v);
default:
BOOST_ASSERT(0);
return 0;
}
#else
return float_hash_impl(v);
#endif
}
}
}