interval/detail/x86_rounding_control.hpp

0001 /* Boost interval/detail/x86_rounding_control.hpp file
0002  *
0003  * Copyright 2000 Jens Maurer
0004  * Copyright 2002 Hervé Brönnimann, Guillaume Melquiond, Sylvain Pion
0005  *
0006  * Distributed under the Boost Software License, Version 1.0.
0007  * (See accompanying file LICENSE_1_0.txt or
0008  * copy at http://www.boost.org/LICENSE_1_0.txt)
0009  */
0010
0011 #ifndef BOOST_NUMERIC_INTERVAL_DETAIL_X86_ROUNDING_CONTROL_HPP
0012 #define BOOST_NUMERIC_INTERVAL_DETAIL_X86_ROUNDING_CONTROL_HPP
0013
0014 #if defined(__GNUC__) || defined(__BORLANDC__) && defined(__clang__)
0015 #  include <boost/numeric/interval/detail/x86gcc_rounding_control.hpp>
0016 #elif defined(__BORLANDC__)
0017 #  include <boost/numeric/interval/detail/bcc_rounding_control.hpp>
0018 #elif defined(_MSC_VER)
0019 #  include <boost/numeric/interval/detail/msvc_rounding_control.hpp>
0020 #elif defined(__MWERKS__) || defined(__ICC) || defined (__SUNPRO_CC)
0021 #  define BOOST_NUMERIC_INTERVAL_USE_C99_SUBSYSTEM
0022 #  include <boost/numeric/interval/detail/c99sub_rounding_control.hpp>
0023 #else
0024 #  error Unsupported C++ compiler.
0025 #endif
0026
0027 namespace boost {
0028 namespace numeric {
0029 namespace interval_lib {
0030
0031 namespace detail {
0032
0033 #ifdef BOOST_NUMERIC_INTERVAL_USE_C99_SUBSYSTEM
0034 typedef c99_rounding_control x86_rounding_control;
0035 #undef BOOST_NUMERIC_INTERVAL_USE_C99_SUBSYSTEM
0036 #else
0037 struct fpu_rounding_modes
0038 {
0039   unsigned short to_nearest;
0040   unsigned short downward;
0041   unsigned short upward;
0042   unsigned short toward_zero;
0043 };
0044
0045 // exceptions masked, extended precision
0046 // hardware default is 0x037f (0x1000 only has a meaning on 287)
0047 static const fpu_rounding_modes rnd_mode = { 0x137f, 0x177f, 0x1b7f, 0x1f7f };
0048
0049 struct x86_rounding_control: x86_rounding
0050 {
0051   static void to_nearest()  { set_rounding_mode(rnd_mode.to_nearest);  }
0052   static void downward()    { set_rounding_mode(rnd_mode.downward);    }
0053   static void upward()      { set_rounding_mode(rnd_mode.upward);      }
0054   static void toward_zero() { set_rounding_mode(rnd_mode.toward_zero); }
0055 };
0056 #endif // BOOST_NUMERIC_INTERVAL_USE_C99_SUBSYSTEM
0057
0058 } // namespace detail
0059
0060 template<>
0061 struct rounding_control<float>: detail::x86_rounding_control
0062 {
0063   static float force_rounding(const float& r)
0064   { volatile float r_ = r; return r_; }
0065 };
0066
0067 template<>
0068 struct rounding_control<double>: detail::x86_rounding_control
0069 {
0070   /*static double force_rounding(double r)
0071   { asm volatile ("" : "+m"(r) : ); return r; }*/
0072   static double force_rounding(const double& r)
0073   { volatile double r_ = r; return r_; }
0074 };
0075
0076 namespace detail {
0077
0078 template<bool>
0079 struct x86_rounding_control_long_double;
0080
0081 template<>
0082 struct x86_rounding_control_long_double<false>: x86_rounding_control
0083 {
0084   static long double force_rounding(long double const &r)
0085   { volatile long double r_ = r; return r_; }
0086 };
0087
0088 template<>
0089 struct x86_rounding_control_long_double<true>: x86_rounding_control
0090 {
0091   static long double const &force_rounding(long double const &r)
0092   { return r; }
0093 };
0094
0095 } // namespace detail
0096
0097 template<>
0098 struct rounding_control<long double>:
0099   detail::x86_rounding_control_long_double< (sizeof(long double) >= 10) >
0100 {};
0101
0102 } // namespace interval_lib
0103 } // namespace numeric
0104 } // namespace boost
0105
0106 #undef BOOST_NUMERIC_INTERVAL_NO_HARDWARE
0107
0108 #endif /* BOOST_NUMERIC_INTERVAL_DETAIL_X86_ROUNDING_CONTROL_HPP */