/* Boost interval/detail/msvc_rounding_control.hpp file

 *

 * Copyright 2000 Maarten Keijzer

 * Copyright 2002 Hervé Brönnimann, Guillaume Melquiond, Sylvain Pion

 *

 * Distributed under the Boost Software License, Version 1.0.

 * (See accompanying file LICENSE_1_0.txt or

 * copy at http://www.boost.org/LICENSE_1_0.txt)

 */



#ifndef BOOST_NUMERIC_INTERVAL_DETAIL_MSVC_ROUNDING_CONTROL_HPP

#define BOOST_NUMERIC_INTERVAL_DETAIL_MSVC_ROUNDING_CONTROL_HPP



#ifndef _MSC_VER

#  error This header is only intended for MSVC, but might work for Borland as well

#endif



#include <float.h>      // MSVC rounding control



// Although the function is called _control87, it seems to work for

// other FPUs too, so it does not have to be changed to _controlfp.



namespace boost {

namespace numeric {

namespace interval_lib {

namespace detail {



extern "C" { double rint(double); }



struct x86_rounding

{

  static unsigned int hard2msvc(unsigned short m) {

    unsigned int n = 0;

    if (m & 0x01) n |= _EM_INVALID;

    if (m & 0x02) n |= _EM_DENORMAL;

    if (m & 0x04) n |= _EM_ZERODIVIDE;

    if (m & 0x08) n |= _EM_OVERFLOW;

    if (m & 0x10) n |= _EM_UNDERFLOW;

    if (m & 0x20) n |= _EM_INEXACT;

    switch (m & 0x300) {

    case 0x000: n |= _PC_24; break;

    case 0x200: n |= _PC_53; break;

    case 0x300: n |= _PC_64; break;

    }

    switch (m & 0xC00) {

    case 0x000: n |= _RC_NEAR; break;

    case 0x400: n |= _RC_DOWN; break;

    case 0x800: n |= _RC_UP;   break;

    case 0xC00: n |= _RC_CHOP; break;

    }

    if (m & 0x1000) n |= _IC_AFFINE; // only useful on 287

    return n;

  }



  static unsigned short msvc2hard(unsigned int n) {

    unsigned short m = 0;

    if (n & _EM_INVALID)    m |= 0x01;

    if (n & _EM_DENORMAL)   m |= 0x02;

    if (n & _EM_ZERODIVIDE) m |= 0x04;

    if (n & _EM_OVERFLOW)   m |= 0x08;

    if (n & _EM_UNDERFLOW)  m |= 0x10;

    if (n & _EM_INEXACT)    m |= 0x20;

    switch (n & _MCW_RC) {

    case _RC_NEAR: m |= 0x000; break;

    case _RC_DOWN: m |= 0x400; break;

    case _RC_UP:   m |= 0x800; break;

    case _RC_CHOP: m |= 0xC00; break;

    }

    switch (n & _MCW_PC) {

    case _PC_24: m |= 0x000; break;

    case _PC_53: m |= 0x200; break;

    case _PC_64: m |= 0x300; break;

    }

    if ((n & _MCW_IC) == _IC_AFFINE) m |= 0x1000;

    return m;

  }



  typedef unsigned short rounding_mode;

  static void get_rounding_mode(rounding_mode& mode)

  { mode = msvc2hard(_control87(0, 0)); }

  static void set_rounding_mode(const rounding_mode mode)

  { _control87(hard2msvc(mode), _MCW_EM | _MCW_RC | _MCW_PC | _MCW_IC); }

  static double to_int(const double& x) { return rint(x); }

};



} // namespace detail

} // namespace interval_lib

} // namespace numeric

} // namespace boost



#endif /* BOOST_NUMERIC_INTERVAL_DETAIL_MSVC_ROUNDING_CONTROL_HPP */

