ceph/src/boost/libs/numeric/interval/include/boost/numeric/interval/detail/alpha_rounding_control.hpp

   1 /* Boost interval/detail/alpha_rounding_control.hpp file
   2  *
   3  * Copyright 2005 Felix Höfling, Guillaume Melquiond
   4  *
   5  * Distributed under the Boost Software License, Version 1.0.
   6  * (See accompanying file LICENSE_1_0.txt or
   7  * copy at http://www.boost.org/LICENSE_1_0.txt)
   8  */
   9
  10 #ifndef BOOST_NUMERIC_INTERVAL_DETAIL_ALPHA_ROUNDING_CONTROL_HPP
  11 #define BOOST_NUMERIC_INTERVAL_DETAIL_ALPHA_ROUNDING_CONTROL_HPP
  12
  13 #if !defined(alpha) && !defined(__alpha__)
  14 #error This header only works on Alpha CPUs.
  15 #endif
  16
  17 #if defined(__GNUC__) || defined(__digital__) || defined(__DECCXX)
  18
  19 #include <float.h> // write_rnd() and read_rnd()
  20
  21 namespace boost {
  22 namespace numeric {
  23 namespace interval_lib {
  24
  25 namespace detail {
  26 #if defined(__GNUC__ )
  27     typedef union {
  28     ::boost::long_long_type imode;
  29     double dmode;
  30     } rounding_mode_struct;
  31
  32     // set bits 59-58 (DYN),
  33     // clear all exception bits and disable overflow (51) and inexact exceptions (62)
  34     static const rounding_mode_struct mode_upward      = { 0x4C08000000000000LL };
  35     static const rounding_mode_struct mode_downward    = { 0x4408000000000000LL };
  36     static const rounding_mode_struct mode_to_nearest  = { 0x4808000000000000LL };
  37     static const rounding_mode_struct mode_toward_zero = { 0x4008000000000000LL };
  38
  39     struct alpha_rounding_control
  40     {
  41     typedef double rounding_mode;
  42
  43     static void set_rounding_mode(const rounding_mode mode)
  44     { __asm__ __volatile__ ("mt_fpcr %0" : : "f"(mode)); }
  45
  46     static void get_rounding_mode(rounding_mode& mode)
  47     { __asm__ __volatile__ ("mf_fpcr %0" : "=f"(mode)); }
  48
  49     static void downward()    { set_rounding_mode(mode_downward.dmode);    }
  50     static void upward()      { set_rounding_mode(mode_upward.dmode);      }
  51     static void to_nearest()  { set_rounding_mode(mode_to_nearest.dmode);  }
  52     static void toward_zero() { set_rounding_mode(mode_toward_zero.dmode); }
  53     };
  54 #elif defined(__digital__) || defined(__DECCXX)
  55
  56 #if defined(__DECCXX) && !(defined(__FLT_ROUNDS) && __FLT_ROUNDS == -1)
  57 #error Dynamic rounding mode not enabled. See cxx man page for details.
  58 #endif
  59
  60     struct alpha_rounding_control
  61     {
  62     typedef unsigned int rounding_mode;
  63
  64     static void set_rounding_mode(const rounding_mode& mode)  { write_rnd(mode); }
  65     static void get_rounding_mode(rounding_mode& mode)  { mode = read_rnd(); }
  66
  67     static void downward()    { set_rounding_mode(FP_RND_RM); }
  68     static void upward()      { set_rounding_mode(FP_RND_RP); }
  69     static void to_nearest()  { set_rounding_mode(FP_RND_RN); }
  70     static void toward_zero() { set_rounding_mode(FP_RND_RZ); }
  71     };
  72 #endif
  73 } // namespace detail
  74
  75 extern "C" {
  76   float rintf(float);
  77   double rint(double);
  78   long double rintl(long double);
  79 }
  80
  81 template<>
  82 struct rounding_control<float>:
  83   detail::alpha_rounding_control
  84 {
  85   static float force_rounding(const float r)
  86   { volatile float _r = r; return _r; }
  87   static float to_int(const float& x) { return rintf(x); }
  88 };
  89
  90 template<>
  91 struct rounding_control<double>:
  92   detail::alpha_rounding_control
  93 {
  94   static const double & force_rounding(const double& r) { return r; }
  95   static double to_int(const double& r) { return rint(r); }
  96 };
  97
  98 template<>
  99 struct rounding_control<long double>:
 100   detail::alpha_rounding_control
 101 {
 102   static const long double & force_rounding(const long double& r) { return r; }
 103   static long double to_int(const long double& r) { return rintl(r); }
 104 };
 105
 106 } // namespace interval_lib
 107 } // namespace numeric
 108 } // namespace boost
 109
 110 #undef BOOST_NUMERIC_INTERVAL_NO_HARDWARE
 111 #endif
 112
 113 #endif /* BOOST_NUMERIC_INTERVAL_DETAIL_ALPHA_ROUNDING_CONTROL_HPP */