571 lines
16 KiB
C++
571 lines
16 KiB
C++
// fp_traits.hpp
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#ifndef BOOST_MATH_FP_TRAITS_HPP
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#define BOOST_MATH_FP_TRAITS_HPP
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// Copyright (c) 2006 Johan Rade
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt
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// or copy at http://www.boost.org/LICENSE_1_0.txt)
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/*
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To support old compilers, care has been taken to avoid partial template
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specialization and meta function forwarding.
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With these techniques, the code could be simplified.
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*/
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#if defined(__vms) && defined(__DECCXX) && !__IEEE_FLOAT
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// The VAX floating point formats are used (for float and double)
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# define BOOST_FPCLASSIFY_VAX_FORMAT
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#endif
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#include <cstring>
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#include <boost/assert.hpp>
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#include <boost/cstdint.hpp>
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#include <boost/detail/endian.hpp>
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#include <boost/static_assert.hpp>
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#include <boost/type_traits/is_floating_point.hpp>
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#ifdef BOOST_NO_STDC_NAMESPACE
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namespace std{ using ::memcpy; }
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#endif
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#ifndef FP_NORMAL
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#define FP_ZERO 0
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#define FP_NORMAL 1
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#define FP_INFINITE 2
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#define FP_NAN 3
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#define FP_SUBNORMAL 4
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#else
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#define BOOST_HAS_FPCLASSIFY
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#ifndef fpclassify
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# if (defined(__GLIBCPP__) || defined(__GLIBCXX__)) \
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&& defined(_GLIBCXX_USE_C99_MATH) \
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&& !(defined(_GLIBCXX_USE_C99_FP_MACROS_DYNAMIC) \
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&& (_GLIBCXX_USE_C99_FP_MACROS_DYNAMIC != 0))
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# ifdef _STLP_VENDOR_CSTD
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# if _STLPORT_VERSION >= 0x520
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# define BOOST_FPCLASSIFY_PREFIX ::__std_alias::
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# else
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# define BOOST_FPCLASSIFY_PREFIX ::_STLP_VENDOR_CSTD::
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# endif
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# else
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# define BOOST_FPCLASSIFY_PREFIX ::std::
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# endif
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# else
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# undef BOOST_HAS_FPCLASSIFY
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# define BOOST_FPCLASSIFY_PREFIX
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# endif
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#elif (defined(__HP_aCC) && !defined(__hppa))
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// aCC 6 appears to do "#define fpclassify fpclassify" which messes us up a bit!
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# define BOOST_FPCLASSIFY_PREFIX ::
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#else
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# define BOOST_FPCLASSIFY_PREFIX
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#endif
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#ifdef __MINGW32__
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# undef BOOST_HAS_FPCLASSIFY
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#endif
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#endif
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//------------------------------------------------------------------------------
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namespace boost {
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namespace math {
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namespace detail {
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//------------------------------------------------------------------------------
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/*
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The following classes are used to tag the different methods that are used
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for floating point classification
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*/
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struct native_tag {};
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template <bool has_limits>
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struct generic_tag {};
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struct ieee_tag {};
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struct ieee_copy_all_bits_tag : public ieee_tag {};
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struct ieee_copy_leading_bits_tag : public ieee_tag {};
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#ifdef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
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//
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// These helper functions are used only when numeric_limits<>
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// members are not compile time constants:
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//
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inline bool is_generic_tag_false(const generic_tag<false>*)
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{
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return true;
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}
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inline bool is_generic_tag_false(const void*)
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{
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return false;
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}
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#endif
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//------------------------------------------------------------------------------
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/*
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Most processors support three different floating point precisions:
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single precision (32 bits), double precision (64 bits)
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and extended double precision (80 - 128 bits, depending on the processor)
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Note that the C++ type long double can be implemented
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both as double precision and extended double precision.
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*/
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struct unknown_precision{};
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struct single_precision {};
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struct double_precision {};
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struct extended_double_precision {};
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// native_tag version --------------------------------------------------------------
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template<class T> struct fp_traits_native
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{
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typedef native_tag method;
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};
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// generic_tag version -------------------------------------------------------------
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template<class T, class U> struct fp_traits_non_native
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{
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#ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
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typedef generic_tag<std::numeric_limits<T>::is_specialized> method;
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#else
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typedef generic_tag<false> method;
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#endif
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};
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// ieee_tag versions ---------------------------------------------------------------
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/*
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These specializations of fp_traits_non_native contain information needed
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to "parse" the binary representation of a floating point number.
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Typedef members:
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bits -- the target type when copying the leading bytes of a floating
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point number. It is a typedef for uint32_t or uint64_t.
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method -- tells us whether all bytes are copied or not.
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It is a typedef for ieee_copy_all_bits_tag or ieee_copy_leading_bits_tag.
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Static data members:
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sign, exponent, flag, significand -- bit masks that give the meaning of the
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bits in the leading bytes.
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Static function members:
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get_bits(), set_bits() -- provide access to the leading bytes.
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*/
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// ieee_tag version, float (32 bits) -----------------------------------------------
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#ifndef BOOST_FPCLASSIFY_VAX_FORMAT
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template<> struct fp_traits_non_native<float, single_precision>
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{
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typedef ieee_copy_all_bits_tag method;
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BOOST_STATIC_CONSTANT(uint32_t, sign = 0x80000000u);
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BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7f800000);
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BOOST_STATIC_CONSTANT(uint32_t, flag = 0x00000000);
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BOOST_STATIC_CONSTANT(uint32_t, significand = 0x007fffff);
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typedef uint32_t bits;
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static void get_bits(float x, uint32_t& a) { std::memcpy(&a, &x, 4); }
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static void set_bits(float& x, uint32_t a) { std::memcpy(&x, &a, 4); }
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};
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// ieee_tag version, double (64 bits) ----------------------------------------------
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#if defined(BOOST_NO_INT64_T) || defined(BOOST_NO_INCLASS_MEMBER_INITIALIZATION) \
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|| defined(__BORLANDC__) || defined(__CODEGEAR__)
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template<> struct fp_traits_non_native<double, double_precision>
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{
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typedef ieee_copy_leading_bits_tag method;
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BOOST_STATIC_CONSTANT(uint32_t, sign = 0x80000000u);
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BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7ff00000);
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BOOST_STATIC_CONSTANT(uint32_t, flag = 0);
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BOOST_STATIC_CONSTANT(uint32_t, significand = 0x000fffff);
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typedef uint32_t bits;
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static void get_bits(double x, uint32_t& a)
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{
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std::memcpy(&a, reinterpret_cast<const unsigned char*>(&x) + offset_, 4);
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}
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static void set_bits(double& x, uint32_t a)
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{
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std::memcpy(reinterpret_cast<unsigned char*>(&x) + offset_, &a, 4);
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}
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private:
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#if defined(BOOST_BIG_ENDIAN)
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BOOST_STATIC_CONSTANT(int, offset_ = 0);
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#elif defined(BOOST_LITTLE_ENDIAN)
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BOOST_STATIC_CONSTANT(int, offset_ = 4);
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#else
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BOOST_STATIC_ASSERT(false);
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#endif
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};
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//..............................................................................
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#else
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template<> struct fp_traits_non_native<double, double_precision>
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{
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typedef ieee_copy_all_bits_tag method;
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static const uint64_t sign = ((uint64_t)0x80000000u) << 32;
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static const uint64_t exponent = ((uint64_t)0x7ff00000) << 32;
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static const uint64_t flag = 0;
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static const uint64_t significand
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= (((uint64_t)0x000fffff) << 32) + ((uint64_t)0xffffffffu);
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typedef uint64_t bits;
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static void get_bits(double x, uint64_t& a) { std::memcpy(&a, &x, 8); }
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static void set_bits(double& x, uint64_t a) { std::memcpy(&x, &a, 8); }
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};
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#endif
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#endif // #ifndef BOOST_FPCLASSIFY_VAX_FORMAT
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// long double (64 bits) -------------------------------------------------------
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#if defined(BOOST_NO_INT64_T) || defined(BOOST_NO_INCLASS_MEMBER_INITIALIZATION)\
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|| defined(__BORLANDC__) || defined(__CODEGEAR__)
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template<> struct fp_traits_non_native<long double, double_precision>
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{
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typedef ieee_copy_leading_bits_tag method;
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BOOST_STATIC_CONSTANT(uint32_t, sign = 0x80000000u);
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BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7ff00000);
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BOOST_STATIC_CONSTANT(uint32_t, flag = 0);
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BOOST_STATIC_CONSTANT(uint32_t, significand = 0x000fffff);
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typedef uint32_t bits;
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static void get_bits(long double x, uint32_t& a)
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{
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std::memcpy(&a, reinterpret_cast<const unsigned char*>(&x) + offset_, 4);
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}
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static void set_bits(long double& x, uint32_t a)
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{
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std::memcpy(reinterpret_cast<unsigned char*>(&x) + offset_, &a, 4);
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}
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private:
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#if defined(BOOST_BIG_ENDIAN)
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BOOST_STATIC_CONSTANT(int, offset_ = 0);
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#elif defined(BOOST_LITTLE_ENDIAN)
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BOOST_STATIC_CONSTANT(int, offset_ = 4);
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#else
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BOOST_STATIC_ASSERT(false);
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#endif
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};
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//..............................................................................
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#else
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template<> struct fp_traits_non_native<long double, double_precision>
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{
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typedef ieee_copy_all_bits_tag method;
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static const uint64_t sign = (uint64_t)0x80000000u << 32;
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static const uint64_t exponent = (uint64_t)0x7ff00000 << 32;
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static const uint64_t flag = 0;
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static const uint64_t significand
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= ((uint64_t)0x000fffff << 32) + (uint64_t)0xffffffffu;
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typedef uint64_t bits;
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static void get_bits(long double x, uint64_t& a) { std::memcpy(&a, &x, 8); }
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static void set_bits(long double& x, uint64_t a) { std::memcpy(&x, &a, 8); }
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};
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#endif
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// long double (>64 bits), x86 and x64 -----------------------------------------
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#if defined(__i386) || defined(__i386__) || defined(_M_IX86) \
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|| defined(__amd64) || defined(__amd64__) || defined(_M_AMD64) \
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|| defined(__x86_64) || defined(__x86_64__) || defined(_M_X64)
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// Intel extended double precision format (80 bits)
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template<>
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struct fp_traits_non_native<long double, extended_double_precision>
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{
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typedef ieee_copy_leading_bits_tag method;
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BOOST_STATIC_CONSTANT(uint32_t, sign = 0x80000000u);
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BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7fff0000);
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BOOST_STATIC_CONSTANT(uint32_t, flag = 0x00008000);
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BOOST_STATIC_CONSTANT(uint32_t, significand = 0x00007fff);
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typedef uint32_t bits;
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static void get_bits(long double x, uint32_t& a)
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{
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std::memcpy(&a, reinterpret_cast<const unsigned char*>(&x) + 6, 4);
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}
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static void set_bits(long double& x, uint32_t a)
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{
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std::memcpy(reinterpret_cast<unsigned char*>(&x) + 6, &a, 4);
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}
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};
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// long double (>64 bits), Itanium ---------------------------------------------
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#elif defined(__ia64) || defined(__ia64__) || defined(_M_IA64)
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// The floating point format is unknown at compile time
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// No template specialization is provided.
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// The generic_tag definition is used.
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// The Itanium supports both
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// the Intel extended double precision format (80 bits) and
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// the IEEE extended double precision format with 15 exponent bits (128 bits).
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// long double (>64 bits), PowerPC ---------------------------------------------
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#elif defined(__powerpc) || defined(__powerpc__) || defined(__POWERPC__) \
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|| defined(__ppc) || defined(__ppc__) || defined(__PPC__)
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// PowerPC extended double precision format (128 bits)
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template<>
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struct fp_traits_non_native<long double, extended_double_precision>
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{
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typedef ieee_copy_leading_bits_tag method;
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BOOST_STATIC_CONSTANT(uint32_t, sign = 0x80000000u);
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BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7ff00000);
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BOOST_STATIC_CONSTANT(uint32_t, flag = 0x00000000);
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BOOST_STATIC_CONSTANT(uint32_t, significand = 0x000fffff);
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typedef uint32_t bits;
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static void get_bits(long double x, uint32_t& a)
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{
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std::memcpy(&a, reinterpret_cast<const unsigned char*>(&x) + offset_, 4);
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}
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static void set_bits(long double& x, uint32_t a)
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{
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std::memcpy(reinterpret_cast<unsigned char*>(&x) + offset_, &a, 4);
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}
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private:
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#if defined(BOOST_BIG_ENDIAN)
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BOOST_STATIC_CONSTANT(int, offset_ = 0);
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#elif defined(BOOST_LITTLE_ENDIAN)
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BOOST_STATIC_CONSTANT(int, offset_ = 12);
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#else
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BOOST_STATIC_ASSERT(false);
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#endif
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};
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// long double (>64 bits), Motorola 68K ----------------------------------------
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#elif defined(__m68k) || defined(__m68k__) \
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|| defined(__mc68000) || defined(__mc68000__) \
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// Motorola extended double precision format (96 bits)
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// It is the same format as the Intel extended double precision format,
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// except that 1) it is big-endian, 2) the 3rd and 4th byte are padding, and
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// 3) the flag bit is not set for infinity
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template<>
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struct fp_traits_non_native<long double, extended_double_precision>
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{
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typedef ieee_copy_leading_bits_tag method;
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BOOST_STATIC_CONSTANT(uint32_t, sign = 0x80000000u);
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BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7fff0000);
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BOOST_STATIC_CONSTANT(uint32_t, flag = 0x00008000);
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BOOST_STATIC_CONSTANT(uint32_t, significand = 0x00007fff);
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// copy 1st, 2nd, 5th and 6th byte. 3rd and 4th byte are padding.
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typedef uint32_t bits;
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static void get_bits(long double x, uint32_t& a)
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{
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std::memcpy(&a, &x, 2);
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std::memcpy(reinterpret_cast<unsigned char*>(&a) + 2,
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reinterpret_cast<const unsigned char*>(&x) + 4, 2);
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}
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static void set_bits(long double& x, uint32_t a)
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{
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std::memcpy(&x, &a, 2);
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std::memcpy(reinterpret_cast<unsigned char*>(&x) + 4,
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reinterpret_cast<const unsigned char*>(&a) + 2, 2);
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}
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};
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// long double (>64 bits), All other processors --------------------------------
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#else
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// IEEE extended double precision format with 15 exponent bits (128 bits)
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template<>
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struct fp_traits_non_native<long double, extended_double_precision>
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{
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typedef ieee_copy_leading_bits_tag method;
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BOOST_STATIC_CONSTANT(uint32_t, sign = 0x80000000u);
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BOOST_STATIC_CONSTANT(uint32_t, exponent = 0x7fff0000);
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BOOST_STATIC_CONSTANT(uint32_t, flag = 0x00000000);
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BOOST_STATIC_CONSTANT(uint32_t, significand = 0x0000ffff);
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typedef uint32_t bits;
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static void get_bits(long double x, uint32_t& a)
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{
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std::memcpy(&a, reinterpret_cast<const unsigned char*>(&x) + offset_, 4);
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}
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static void set_bits(long double& x, uint32_t a)
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{
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std::memcpy(reinterpret_cast<unsigned char*>(&x) + offset_, &a, 4);
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}
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private:
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#if defined(BOOST_BIG_ENDIAN)
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BOOST_STATIC_CONSTANT(int, offset_ = 0);
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#elif defined(BOOST_LITTLE_ENDIAN)
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BOOST_STATIC_CONSTANT(int, offset_ = 12);
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#else
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BOOST_STATIC_ASSERT(false);
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#endif
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};
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#endif
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//------------------------------------------------------------------------------
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// size_to_precision is a type switch for converting a C++ floating point type
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// to the corresponding precision type.
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template<int n, bool fp> struct size_to_precision
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{
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typedef unknown_precision type;
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};
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template<> struct size_to_precision<4, true>
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{
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typedef single_precision type;
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};
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template<> struct size_to_precision<8, true>
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{
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typedef double_precision type;
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};
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template<> struct size_to_precision<10, true>
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{
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typedef extended_double_precision type;
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};
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template<> struct size_to_precision<12, true>
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{
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typedef extended_double_precision type;
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};
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template<> struct size_to_precision<16, true>
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{
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typedef extended_double_precision type;
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};
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//------------------------------------------------------------------------------
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//
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// Figure out whether to use native classification functions based on
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// whether T is a built in floating point type or not:
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//
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template <class T>
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struct select_native
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{
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typedef BOOST_DEDUCED_TYPENAME size_to_precision<sizeof(T), ::boost::is_floating_point<T>::value>::type precision;
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typedef fp_traits_non_native<T, precision> type;
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};
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template<>
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struct select_native<float>
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{
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typedef fp_traits_native<float> type;
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};
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template<>
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struct select_native<double>
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{
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typedef fp_traits_native<double> type;
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};
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template<>
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struct select_native<long double>
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{
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typedef fp_traits_native<long double> type;
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};
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//------------------------------------------------------------------------------
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// fp_traits is a type switch that selects the right fp_traits_non_native
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#if (defined(BOOST_MATH_USE_C99) && !(defined(__GNUC__) && (__GNUC__ < 4))) \
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&& !defined(__hpux) \
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&& !defined(__DECCXX)\
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&& !defined(__osf__) \
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&& !defined(__SGI_STL_PORT) && !defined(_STLPORT_VERSION)\
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&& !defined(BOOST_MATH_DISABLE_STD_FPCLASSIFY)
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# define BOOST_MATH_USE_STD_FPCLASSIFY
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#endif
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template<class T> struct fp_traits
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{
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typedef BOOST_DEDUCED_TYPENAME size_to_precision<sizeof(T), ::boost::is_floating_point<T>::value>::type precision;
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#if defined(BOOST_MATH_USE_STD_FPCLASSIFY) && !defined(BOOST_MATH_DISABLE_STD_FPCLASSIFY)
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typedef typename select_native<T>::type type;
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#else
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typedef fp_traits_non_native<T, precision> type;
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#endif
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typedef fp_traits_non_native<T, precision> sign_change_type;
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};
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//------------------------------------------------------------------------------
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|
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} // namespace detail
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} // namespace math
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} // namespace boost
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|
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#endif
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