fp_traits.hpp

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    static void init() {}
    static void get_bits(double x, uint64_t& a) { memcpy(&a, &x, 8); }
    static void set_bits(double& x, uint64_t a) { memcpy(&x, &a, 8); }
};

#endif


// long double (64 bits) -------------------------------------------------------

#if defined(BOOST_NO_INT64_T) || defined(BOOST_NO_INCLASS_MEMBER_INITIALIZATION)

template<> struct fp_traits_impl<long double, double_precision_tag>
{
    typedef uint32_t bits;
    typedef not_all_bits coverage;

    BOOST_STATIC_CONSTANT(uint32_t, sign     = 0x80000000);
    BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7ff00000);
    BOOST_STATIC_CONSTANT(uint32_t, flag     = 0);
    BOOST_STATIC_CONSTANT(uint32_t, mantissa = 0x000fffff);

    static void init() {}

    static void get_bits(long double x, uint32_t& a)
    {
        memcpy(&a, reinterpret_cast<const unsigned char*>(&x) + offset_, 4);
    }

    static void set_bits(long double& x, uint32_t a)
    {
        memcpy(reinterpret_cast<unsigned char*>(&x) + offset_, &a, 4);
    }

private:

#if defined(BOOST_BIG_ENDIAN)
    BOOST_STATIC_CONSTANT(int, offset_ = 0);
#elif defined(BOOST_LITTLE_ENDIAN)
    BOOST_STATIC_CONSTANT(int, offset_ = 4);
#else
    BOOST_STATIC_ASSERT(false);
#endif
};

//..............................................................................

#else

template<> struct fp_traits_impl<long double, double_precision_tag>
{
    typedef uint64_t bits;
    typedef all_bits coverage;

    static const uint64_t sign     = (uint64_t)0x80000000 << 32;
    static const uint64_t exponent = (uint64_t)0x7ff00000 << 32;
    static const uint64_t flag     = 0;
    static const uint64_t mantissa
        = ((uint64_t)0x000fffff << 32) + (uint64_t)0xffffffff;

    static void init() {}
    static void get_bits(long double x, uint64_t& a) { memcpy(&a, &x, 8); }
    static void set_bits(long double& x, uint64_t a) { memcpy(&x, &a, 8); }
};

#endif


// long double (>64 bits), x86 and x64 -----------------------------------------

#if defined(__i386) || defined(__i386__) || defined(_M_IX86) \
    || defined(__amd64) || defined(__amd64__)  || defined(_M_AMD64) \
    || defined(__x86_64) || defined(__x86_64__) || defined(_M_X64)

// Intel extended double precision format (80 bits)

template<> struct fp_traits_impl<long double, extended_double_precision_tag>
{
    typedef uint32_t bits;
    typedef not_all_bits coverage;

    BOOST_STATIC_CONSTANT(uint32_t, sign     = 0x80000000);
    BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7fff0000);
    BOOST_STATIC_CONSTANT(uint32_t, flag     = 0x00008000);
    BOOST_STATIC_CONSTANT(uint32_t, mantissa = 0x00007fff);

    static void init() {}

    static void get_bits(long double x, uint32_t& a)
    {
        memcpy(&a, reinterpret_cast<const unsigned char*>(&x) + 6, 4);
    }

    static void set_bits(long double& x, uint32_t a)
    {
        memcpy(reinterpret_cast<unsigned char*>(&x) + 6, &a, 4);
    }
};


// long double (>64 bits), Itanium ---------------------------------------------

#elif defined(__ia64) || defined(__ia64__) || defined(_M_IA64)

// The floating point format is unknown at compile time
// No template specialization is provided.
// The generic definition is used.

// The Itanium supports both
// the Intel extended double precision format (80 bits) and
// the IEEE extended double precision format with 15 exponent bits (128 bits).


// long double (>64 bits), PowerPC ---------------------------------------------

#elif defined(__powerpc) || defined(__powerpc__) || defined(__POWERPC__) \
    || defined(__ppc) || defined(__ppc__) || defined(__PPC__)

// PowerPC extended double precision format (128 bits)

template<> struct fp_traits_impl<long double, extended_double_precision_tag>
{
    typedef uint32_t bits;
    typedef not_all_bits coverage;

    BOOST_STATIC_CONSTANT(uint32_t, sign     = 0x80000000);
    BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7ff00000);
    BOOST_STATIC_CONSTANT(uint32_t, flag     = 0x00000000);
    BOOST_STATIC_CONSTANT(uint32_t, mantissa = 0x000fffff);

    static void init() {}

    static void get_bits(long double x, uint32_t& a)
    {
        memcpy(&a, reinterpret_cast<const unsigned char*>(&x) + offset_, 4);
    }

    static void set_bits(long double& x, uint32_t a)
    {
        memcpy(reinterpret_cast<unsigned char*>(&x) + offset_, &a, 4);
    }

private:

#if defined(BOOST_BIG_ENDIAN)
    BOOST_STATIC_CONSTANT(int, offset_ = 0);
#elif defined(BOOST_LITTLE_ENDIAN)
    BOOST_STATIC_CONSTANT(int, offset_ = 12);
#else
    BOOST_STATIC_ASSERT(false);
#endif
};


// long double (>64 bits), Motorola 68K ----------------------------------------

#elif defined(__m68k) || defined(__m68k__) \
    || defined(__mc68000) || defined(__mc68000__) \

// Motorola extended double precision format (96 bits)

// It is the same format as the Intel extended double precision format,
// except that 1) it is big-endian, 2) the 3rd and 4th byte are padding, and
// 3) the flag bit is not set for infinity

template<> struct fp_traits_impl<long double, extended_double_precision_tag>
{
    typedef uint32_t bits;
    typedef not_all_bits coverage;

    BOOST_STATIC_CONSTANT(uint32_t, sign     = 0x80000000);
    BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7fff0000);
    BOOST_STATIC_CONSTANT(uint32_t, flag     = 0x00008000);
    BOOST_STATIC_CONSTANT(uint32_t, mantissa = 0x00007fff);

    static void init() {}

    // copy 1st, 2nd, 5th and 6th byte. 3rd and 4th byte are padding.

    static void get_bits(long double x, uint32_t& a)
    {
        memcpy(&a, &x, 2);
        memcpy(reinterpret_cast<unsigned char*>(&a) + 2,
               reinterpret_cast<const unsigned char*>(&x) + 4, 2);
    }

    static void set_bits(long double& x, uint32_t a)
    {
        memcpy(&x, &a, 2);
        memcpy(reinterpret_cast<unsigned char*>(&x) + 4,
               reinterpret_cast<const unsigned char*>(&a) + 2, 2);
    }
};


// long double (>64 bits), All other processors --------------------------------

#else

// IEEE extended double precision format with 15 exponent bits (128 bits)

template<> struct fp_traits_impl<long double, extended_double_precision_tag>
{
    typedef uint32_t bits;
    typedef not_all_bits coverage;

    BOOST_STATIC_CONSTANT(uint32_t, sign     = 0x80000000);
    BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7fff0000);
    BOOST_STATIC_CONSTANT(uint32_t, flag     = 0x00000000);
    BOOST_STATIC_CONSTANT(uint32_t, mantissa = 0x0000ffff);

    static void init() {}

    static void get_bits(long double x, uint32_t& a)
    {
        memcpy(&a, reinterpret_cast<const unsigned char*>(&x) + offset_, 4);
    }

    static void set_bits(long double& x, uint32_t a)
    {
        memcpy(reinterpret_cast<unsigned char*>(&x) + offset_, &a, 4);
    }

private:

#if defined(BOOST_BIG_ENDIAN)
    BOOST_STATIC_CONSTANT(int, offset_ = 0);
#elif defined(BOOST_LITTLE_ENDIAN)
    BOOST_STATIC_CONSTANT(int, offset_ = 12);
#else
    BOOST_STATIC_ASSERT(false);
#endif
};

#endif


//------------------------------------------------------------------------------

// size_to_precision is a type switch for converting a C++ floating point type
// to the corresponding precision type.

template<int n> struct size_to_precision;

template<> struct size_to_precision<4>
{
    typedef single_precision_tag type;
};

template<> struct size_to_precision<8>
{
    typedef double_precision_tag type;
};

template<> struct size_to_precision<10>
{
    typedef extended_double_precision_tag type;
};

template<> struct size_to_precision<12>
{
    typedef extended_double_precision_tag type;
};

template<> struct size_to_precision<16>
{
    typedef extended_double_precision_tag type;
};

// fp_traits is a type switch that selects the right fp_traits_impl

template<class T> struct fp_traits
{
    BOOST_STATIC_ASSERT(boost::is_floating_point<T>::value);
    typedef BOOST_DEDUCED_TYPENAME size_to_precision<sizeof(T)>::type precision;
    typedef fp_traits_impl<T, precision> type;
};


//------------------------------------------------------------------------------

}   // namespace detail
}   // namespace math
}   // namespace boost

#endif