rippled/modules/beast_basics/native/beast_win32_FPUFlags.cpp

//------------------------------------------------------------------------------
/*
    This file is part of Beast: https://github.com/vinniefalco/Beast
    Copyright 2013, Vinnie Falco <vinnie.falco@gmail.com>

    Permission to use, copy, modify, and/or distribute this software for any
    purpose  with  or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.

    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================

FPUFlags FPUFlags::getCurrent ()
{
    unsigned int currentControl;
    const unsigned int newControl = 0;
    const unsigned int mask = 0;

    errno_t result = _controlfp_s (&currentControl, newControl, mask);

    if (result != 0)
        Throw (std::runtime_error ("error in _controlfp_s"));

    FPUFlags flags;

    flags.setMaskNaNs        ((currentControl & _EM_INVALID)    == _EM_INVALID);
    flags.setMaskDenormals   ((currentControl & _EM_DENORMAL)   == _EM_DENORMAL);
    flags.setMaskZeroDivides ((currentControl & _EM_ZERODIVIDE) == _EM_ZERODIVIDE);
    flags.setMaskOverflows   ((currentControl & _EM_OVERFLOW)   == _EM_OVERFLOW);
    flags.setMaskUnderflows  ((currentControl & _EM_UNDERFLOW)  == _EM_UNDERFLOW);
    //flags.setMaskInexacts    ((currentControl & _EM_INEXACT)    == _EM_INEXACT);
    flags.setFlushDenormals  ((currentControl & _DN_FLUSH)      == _DN_FLUSH);
    flags.setInfinitySigned  ((currentControl & _IC_AFFINE)     == _IC_AFFINE);

    Rounding rounding = roundDown;

    switch (currentControl & _MCW_RC)
    {
    case _RC_CHOP:
        rounding = roundChop;
        break;

    case _RC_UP:
        rounding = roundUp;
        break;

    case _RC_DOWN:
        rounding = roundDown;
        break;

    case _RC_NEAR:
        rounding = roundNear;
        break;

    default:
        Throw (std::runtime_error ("unknown rounding in _controlfp_s"));
    };

    flags.setRounding (rounding);

    Precision precision = bits64;

    switch (currentControl & _MCW_PC )
    {
    case _PC_64:
        precision = bits64;
        break;

    case _PC_53:
        precision = bits53;
        break;

    case _PC_24:
        precision = bits24;
        break;

    default:
        Throw (std::runtime_error ("unknown precision in _controlfp_s"));
    };

    flags.setPrecision (precision);

    return flags;
}

static void setControl (const FPUFlags::Flag& flag,
                        unsigned int& newControl,
                        unsigned int& mask,
                        unsigned int constant)
{
    if (flag.is_set ())
    {
        mask |= constant;

        if (flag.value ())
            newControl |= constant;
    }
}

void FPUFlags::setCurrent (const FPUFlags& flags)
{
    unsigned int newControl = 0;
    unsigned int mask = 0;

    setControl (flags.getMaskNaNs (), newControl, mask,        _EM_INVALID);
    setControl (flags.getMaskDenormals (), newControl, mask,   _EM_DENORMAL);
    setControl (flags.getMaskZeroDivides (), newControl, mask, _EM_ZERODIVIDE);
    setControl (flags.getMaskOverflows (), newControl, mask,   _EM_OVERFLOW);
    setControl (flags.getMaskUnderflows (), newControl, mask,  _EM_UNDERFLOW);
    //setControl (flags.getMaskInexacts(), newControl, mask,    _EM_INEXACT);
    setControl (flags.getFlushDenormals (), newControl, mask,  _DN_FLUSH);
    setControl (flags.getInfinitySigned (), newControl, mask,  _IC_AFFINE);

    if (flags.getRounding ().is_set ())
    {
        Rounding rounding = flags.getRounding ().value ();

        switch (rounding)
        {
        case roundChop:
            mask |= _MCW_RC;
            newControl |= _RC_CHOP;
            break;

        case roundUp:
            mask |= _MCW_RC;
            newControl |= _RC_UP;
            break;

        case roundDown:
            mask |= _MCW_RC;
            newControl |= _RC_DOWN;
            break;

        case roundNear:
            mask |= _MCW_RC;
            newControl |= _RC_NEAR;
            break;
        }
    }

    if (flags.getPrecision ().is_set ())
    {
        switch (flags.getPrecision ().value ())
        {
        case bits64:
            mask |= _MCW_PC;
            newControl |= _PC_64;
            break;

        case bits53:
            mask |= _MCW_PC;
            newControl |= _PC_53;
            break;

        case bits24:
            mask |= _MCW_PC;
            newControl |= _PC_24;
            break;
        }
    }

    unsigned int currentControl;

    errno_t result = _controlfp_s (&currentControl, newControl, mask);

    if (result != 0)
        Throw (std::runtime_error ("error in _controlfp_s"));
}