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

   1 /* Boost interval/detail/msvc_rounding_control.hpp file
   2  *
   3  * Copyright 2000 Maarten Keijzer
   4  * Copyright 2002 Hervé Brönnimann, Guillaume Melquiond, Sylvain Pion
   5  *
   6  * Distributed under the Boost Software License, Version 1.0.
   7  * (See accompanying file LICENSE_1_0.txt or
   8  * copy at http://www.boost.org/LICENSE_1_0.txt)
   9  */
  10
  11 #ifndef BOOST_NUMERIC_INTERVAL_DETAIL_MSVC_ROUNDING_CONTROL_HPP
  12 #define BOOST_NUMERIC_INTERVAL_DETAIL_MSVC_ROUNDING_CONTROL_HPP
  13
  14 #ifndef _MSC_VER
  15 #  error This header is only intended for MSVC, but might work for Borland as well
  16 #endif
  17
  18 #include <float.h>      // MSVC rounding control
  19
  20 // Although the function is called _control87, it seems to work for
  21 // other FPUs too, so it does not have to be changed to _controlfp.
  22
  23 namespace boost {
  24 namespace numeric {
  25 namespace interval_lib {
  26 namespace detail {
  27
  28 #if BOOST_MSVC < 1400 || defined(_WIN64)
  29 extern "C" { double rint(double); }
  30 #else
  31 inline double rint(double x)
  32 {
  33 _asm FLD [x] ;
  34 _asm FRNDINT ;
  35 //_asm RET ;
  36 }
  37 #endif
  38
  39 struct x86_rounding
  40 {
  41   static unsigned int hard2msvc(unsigned short m) {
  42     unsigned int n = 0;
  43     if (m & 0x01) n |= _EM_INVALID;
  44     if (m & 0x02) n |= _EM_DENORMAL;
  45     if (m & 0x04) n |= _EM_ZERODIVIDE;
  46     if (m & 0x08) n |= _EM_OVERFLOW;
  47     if (m & 0x10) n |= _EM_UNDERFLOW;
  48     if (m & 0x20) n |= _EM_INEXACT;
  49     switch (m & 0x300) {
  50     case 0x000: n |= _PC_24; break;
  51     case 0x200: n |= _PC_53; break;
  52     case 0x300: n |= _PC_64; break;
  53     }
  54     switch (m & 0xC00) {
  55     case 0x000: n |= _RC_NEAR; break;
  56     case 0x400: n |= _RC_DOWN; break;
  57     case 0x800: n |= _RC_UP;   break;
  58     case 0xC00: n |= _RC_CHOP; break;
  59     }
  60     if (m & 0x1000) n |= _IC_AFFINE; // only useful on 287
  61     return n;
  62   }
  63
  64   static unsigned short msvc2hard(unsigned int n) {
  65     unsigned short m = 0;
  66     if (n & _EM_INVALID)    m |= 0x01;
  67     if (n & _EM_DENORMAL)   m |= 0x02;
  68     if (n & _EM_ZERODIVIDE) m |= 0x04;
  69     if (n & _EM_OVERFLOW)   m |= 0x08;
  70     if (n & _EM_UNDERFLOW)  m |= 0x10;
  71     if (n & _EM_INEXACT)    m |= 0x20;
  72     switch (n & _MCW_RC) {
  73     case _RC_NEAR: m |= 0x000; break;
  74     case _RC_DOWN: m |= 0x400; break;
  75     case _RC_UP:   m |= 0x800; break;
  76     case _RC_CHOP: m |= 0xC00; break;
  77     }
  78     switch (n & _MCW_PC) {
  79     case _PC_24: m |= 0x000; break;
  80     case _PC_53: m |= 0x200; break;
  81     case _PC_64: m |= 0x300; break;
  82     }
  83     if ((n & _MCW_IC) == _IC_AFFINE) m |= 0x1000;
  84     return m;
  85   }
  86
  87   typedef unsigned short rounding_mode;
  88   static void get_rounding_mode(rounding_mode& mode)
  89   { mode = msvc2hard(_control87(0, 0)); }
  90   static void set_rounding_mode(const rounding_mode mode)
  91   {
  92     _control87(hard2msvc(mode),
  93       _MCW_EM | _MCW_RC
  94 #if !defined(_M_AMD64) && !defined(_M_ARM)
  95       // x64 ignores _MCW_PC and _MCW_IC, and the Debug CRT library actually
  96       // asserts when these are passed to _control87.
  97       // MSDN says on '_control87' that changing precision (_MCW_PC) or
  98       // infinity (_MCW_IC) handling is not supported on the ARM and x64
  99       // architectures and that _control87 raises an assertion
 100       // and the invalid parameter handler is invoked.
 101       | _MCW_PC | _MCW_IC
 102 #endif
 103     );
 104   }
 105   static double to_int(const double& x) { return rint(x); }
 106 };
 107
 108 } // namespace detail
 109 } // namespace interval_lib
 110 } // namespace numeric
 111 } // namespace boost
 112
 113 #endif /* BOOST_NUMERIC_INTERVAL_DETAIL_MSVC_ROUNDING_CONTROL_HPP */