Chris@16: 
Chris@16: // Copyright 2005-2012 Daniel James.
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #if !defined(BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_HEADER)
Chris@16: #define BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_HEADER
Chris@16: 
Chris@101: #include <boost/config.hpp>
Chris@101: #if defined(BOOST_HAS_PRAGMA_ONCE)
Chris@101: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/functional/hash/detail/float_functions.hpp>
Chris@16: #include <boost/functional/hash/detail/limits.hpp>
Chris@16: #include <boost/utility/enable_if.hpp>
Chris@16: #include <boost/integer/static_log2.hpp>
Chris@16: #include <boost/cstdint.hpp>
Chris@16: #include <boost/assert.hpp>
Chris@16: #include <boost/limits.hpp>
Chris@16: #include <cstring>
Chris@16: 
Chris@16: #if defined(BOOST_MSVC)
Chris@16: #pragma warning(push)
Chris@16: #if BOOST_MSVC >= 1400
Chris@16: #pragma warning(disable:6294) // Ill-defined for-loop: initial condition does
Chris@16:                               // not satisfy test. Loop body not executed
Chris@16: #endif
Chris@16: #endif
Chris@16: 
Chris@16: // Can we use fpclassify?
Chris@16: 
Chris@16: // STLport
Chris@16: #if defined(__SGI_STL_PORT) || defined(_STLPORT_VERSION)
Chris@16: #define BOOST_HASH_USE_FPCLASSIFY 0
Chris@16: 
Chris@16: // GNU libstdc++ 3
Chris@16: #elif defined(__GLIBCPP__) || defined(__GLIBCXX__)
Chris@16: #  if (defined(__USE_ISOC99) || defined(_GLIBCXX_USE_C99_MATH)) && \
Chris@16:       !(defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__))
Chris@16: #    define BOOST_HASH_USE_FPCLASSIFY 1
Chris@16: #  else
Chris@16: #    define BOOST_HASH_USE_FPCLASSIFY 0
Chris@16: #  endif
Chris@16: 
Chris@16: // Everything else
Chris@16: #else
Chris@16: #  define BOOST_HASH_USE_FPCLASSIFY 0
Chris@16: #endif
Chris@16: 
Chris@16: namespace boost
Chris@16: {
Chris@16:     namespace hash_detail
Chris@16:     {
Chris@16:         inline void hash_float_combine(std::size_t& seed, std::size_t value)
Chris@16:         {
Chris@16:             seed ^= value + (seed<<6) + (seed>>2);
Chris@16:         }
Chris@16: 
Chris@16:         ////////////////////////////////////////////////////////////////////////
Chris@16:         // Binary hash function
Chris@16:         //
Chris@16:         // Only used for floats with known iec559 floats, and certain values in
Chris@16:         // numeric_limits
Chris@16: 
Chris@16:         inline std::size_t hash_binary(char* ptr, std::size_t length)
Chris@16:         {
Chris@16:             std::size_t seed = 0;
Chris@16: 
Chris@16:             if (length >= sizeof(std::size_t)) {
Chris@101:                 std::memcpy(&seed, ptr, sizeof(std::size_t));
Chris@16:                 length -= sizeof(std::size_t);
Chris@16:                 ptr += sizeof(std::size_t);
Chris@16: 
Chris@16:                 while(length >= sizeof(std::size_t)) {
Chris@16:                     std::size_t buffer = 0;
Chris@16:                     std::memcpy(&buffer, ptr, sizeof(std::size_t));
Chris@16:                     hash_float_combine(seed, buffer);
Chris@16:                     length -= sizeof(std::size_t);
Chris@16:                     ptr += sizeof(std::size_t);
Chris@16:                 }
Chris@16:             }
Chris@16: 
Chris@16:             if (length > 0) {
Chris@16:                 std::size_t buffer = 0;
Chris@16:                 std::memcpy(&buffer, ptr, length);
Chris@16:                 hash_float_combine(seed, buffer);
Chris@16:             }
Chris@16: 
Chris@16:             return seed;
Chris@16:         }
Chris@16: 
Chris@16:         template <typename Float, unsigned digits, unsigned max_exponent>
Chris@16:         struct enable_binary_hash
Chris@16:         {
Chris@16:             BOOST_STATIC_CONSTANT(bool, value =
Chris@16:                 std::numeric_limits<Float>::is_iec559 &&
Chris@16:                 std::numeric_limits<Float>::digits == digits &&
Chris@16:                 std::numeric_limits<Float>::radix == 2 &&
Chris@16:                 std::numeric_limits<Float>::max_exponent == max_exponent);
Chris@16:         };
Chris@16: 
Chris@16:         template <typename Float>
Chris@16:         inline std::size_t float_hash_impl(Float v,
Chris@16:             BOOST_DEDUCED_TYPENAME boost::enable_if_c<
Chris@16:                 enable_binary_hash<Float, 24, 128>::value,
Chris@16:                 std::size_t>::type)
Chris@16:         {
Chris@16:             return hash_binary((char*) &v, 4);
Chris@16:         }
Chris@16: 
Chris@16: 
Chris@16:         template <typename Float>
Chris@16:         inline std::size_t float_hash_impl(Float v,
Chris@16:             BOOST_DEDUCED_TYPENAME boost::enable_if_c<
Chris@16:                 enable_binary_hash<Float, 53, 1024>::value,
Chris@16:                 std::size_t>::type)
Chris@16:         {
Chris@16:             return hash_binary((char*) &v, 8);
Chris@16:         }
Chris@16: 
Chris@16:         template <typename Float>
Chris@16:         inline std::size_t float_hash_impl(Float v,
Chris@16:             BOOST_DEDUCED_TYPENAME boost::enable_if_c<
Chris@16:                 enable_binary_hash<Float, 64, 16384>::value,
Chris@16:                 std::size_t>::type)
Chris@16:         {
Chris@16:             return hash_binary((char*) &v, 10);
Chris@16:         }
Chris@16: 
Chris@16:         template <typename Float>
Chris@16:         inline std::size_t float_hash_impl(Float v,
Chris@16:             BOOST_DEDUCED_TYPENAME boost::enable_if_c<
Chris@16:                 enable_binary_hash<Float, 113, 16384>::value,
Chris@16:                 std::size_t>::type)
Chris@16:         {
Chris@16:             return hash_binary((char*) &v, 16);
Chris@16:         }
Chris@16: 
Chris@16:         ////////////////////////////////////////////////////////////////////////
Chris@16:         // Portable hash function
Chris@16:         //
Chris@16:         // Used as a fallback when the binary hash function isn't supported.
Chris@16: 
Chris@16:         template <class T>
Chris@16:         inline std::size_t float_hash_impl2(T v)
Chris@16:         {
Chris@16:             boost::hash_detail::call_frexp<T> frexp;
Chris@16:             boost::hash_detail::call_ldexp<T> ldexp;
Chris@16: 
Chris@16:             int exp = 0;
Chris@16: 
Chris@16:             v = frexp(v, &exp);
Chris@16: 
Chris@16:             // A postive value is easier to hash, so combine the
Chris@16:             // sign with the exponent and use the absolute value.
Chris@16:             if(v < 0) {
Chris@16:                 v = -v;
Chris@16:                 exp += limits<T>::max_exponent -
Chris@16:                     limits<T>::min_exponent;
Chris@16:             }
Chris@16: 
Chris@16:             v = ldexp(v, limits<std::size_t>::digits);
Chris@16:             std::size_t seed = static_cast<std::size_t>(v);
Chris@16:             v -= static_cast<T>(seed);
Chris@16: 
Chris@16:             // ceiling(digits(T) * log2(radix(T))/ digits(size_t)) - 1;
Chris@16:             std::size_t const length
Chris@16:                 = (limits<T>::digits *
Chris@16:                         boost::static_log2<limits<T>::radix>::value
Chris@16:                         + limits<std::size_t>::digits - 1)
Chris@16:                 / limits<std::size_t>::digits;
Chris@16: 
Chris@16:             for(std::size_t i = 0; i != length; ++i)
Chris@16:             {
Chris@16:                 v = ldexp(v, limits<std::size_t>::digits);
Chris@16:                 std::size_t part = static_cast<std::size_t>(v);
Chris@16:                 v -= static_cast<T>(part);
Chris@16:                 hash_float_combine(seed, part);
Chris@16:             }
Chris@16: 
Chris@16:             hash_float_combine(seed, exp);
Chris@16: 
Chris@16:             return seed;
Chris@16:         }
Chris@16: 
Chris@16: #if !defined(BOOST_HASH_DETAIL_TEST_WITHOUT_GENERIC)
Chris@16:         template <class T>
Chris@16:         inline std::size_t float_hash_impl(T v, ...)
Chris@16:         {
Chris@16:             typedef BOOST_DEDUCED_TYPENAME select_hash_type<T>::type type;
Chris@16:             return float_hash_impl2(static_cast<type>(v));
Chris@16:         }
Chris@16: #endif
Chris@16:     }
Chris@16: }
Chris@16: 
Chris@16: #if BOOST_HASH_USE_FPCLASSIFY
Chris@16: 
Chris@16: #include <boost/config/no_tr1/cmath.hpp>
Chris@16: 
Chris@16: namespace boost
Chris@16: {
Chris@16:     namespace hash_detail
Chris@16:     {
Chris@16:         template <class T>
Chris@16:         inline std::size_t float_hash_value(T v)
Chris@16:         {
Chris@16: #if defined(fpclassify)
Chris@16:             switch (fpclassify(v))
Chris@16: #elif BOOST_HASH_CONFORMANT_FLOATS
Chris@16:             switch (std::fpclassify(v))
Chris@16: #else
Chris@16:             using namespace std;
Chris@16:             switch (fpclassify(v))
Chris@16: #endif
Chris@16:             {
Chris@16:             case FP_ZERO:
Chris@16:                 return 0;
Chris@16:             case FP_INFINITE:
Chris@16:                 return (std::size_t)(v > 0 ? -1 : -2);
Chris@16:             case FP_NAN:
Chris@16:                 return (std::size_t)(-3);
Chris@16:             case FP_NORMAL:
Chris@16:             case FP_SUBNORMAL:
Chris@16:                 return float_hash_impl(v, 0);
Chris@16:             default:
Chris@16:                 BOOST_ASSERT(0);
Chris@16:                 return 0;
Chris@16:             }
Chris@16:         }
Chris@16:     }
Chris@16: }
Chris@16: 
Chris@16: #else // !BOOST_HASH_USE_FPCLASSIFY
Chris@16: 
Chris@16: namespace boost
Chris@16: {
Chris@16:     namespace hash_detail
Chris@16:     {
Chris@16:         template <class T>
Chris@16:         inline bool is_zero(T v)
Chris@16:         {
Chris@16: #if !defined(__GNUC__)
Chris@16:             return v == 0;
Chris@16: #else
Chris@16:             // GCC's '-Wfloat-equal' will complain about comparing
Chris@16:             // v to 0, but because it disables warnings for system
Chris@16:             // headers it won't complain if you use std::equal_to to
Chris@16:             // compare with 0. Resulting in this silliness:
Chris@16:             return std::equal_to<T>()(v, 0);
Chris@16: #endif
Chris@16:         }
Chris@16: 
Chris@16:         template <class T>
Chris@16:         inline std::size_t float_hash_value(T v)
Chris@16:         {
Chris@16:             return boost::hash_detail::is_zero(v) ? 0 : float_hash_impl(v, 0);
Chris@16:         }
Chris@16:     }
Chris@16: }
Chris@16: 
Chris@16: #endif // BOOST_HASH_USE_FPCLASSIFY
Chris@16: 
Chris@16: #undef BOOST_HASH_USE_FPCLASSIFY
Chris@16: 
Chris@16: #if defined(BOOST_MSVC)
Chris@16: #pragma warning(pop)
Chris@16: #endif
Chris@16: 
Chris@16: #endif