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// 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)
#if !defined(BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_HEADER)
#define BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_HEADER
#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
#include <boost/functional/hash/detail/float_functions.hpp>
#include <boost/integer/static_log2.hpp>
#include <boost/cstdint.hpp>
#include <boost/limits.hpp>
#include <boost/assert.hpp>
// 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)
// 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)
// Not using _fpclass because it is only available for double.
#endif
// On OpenBSD, numeric_limits is not reliable for long doubles, but
// the macros defined in <float.h> are.
#if defined(__OpenBSD__)
#include <float.h>
#endif
namespace boost
{
namespace hash_detail
{
template <class T>
struct limits : std::numeric_limits<T> {};
#if defined(__OpenBSD__)
template <>
struct limits<long double>
: std::numeric_limits<long double>
{
static long double epsilon() {
return LDBL_EPSILON;
}
static long double (max)() {
return LDBL_MAX;
}
static long double (min)() {
return LDBL_MIN;
}
BOOST_STATIC_CONSTANT(int, digits = LDBL_MANT_DIG);
BOOST_STATIC_CONSTANT(int, max_exponent = LDBL_MAX_EXP);
BOOST_STATIC_CONSTANT(int, min_exponent = LDBL_MIN_EXP);
};
#endif // __OpenBSD__
inline void hash_float_combine(std::size_t& seed, std::size_t value)
{
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)
{
int exp = 0;
v = boost::hash_detail::call_frexp(v, &exp);
// A postive value is easier to hash, so combine the
// sign with the exponent.
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 = boost::hash_detail::call_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 = boost::hash_detail::call_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;
}
#endif
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;
}
#else
return v == 0 ? 0 : float_hash_impl(v);
#endif
}
}
}
#if defined(BOOST_MSVC)
#pragma warning(pop)
#endif
#endif
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Swift