IexMathFloatExc.h

Go to the documentation of this file.

//
// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) Contributors to the OpenEXR Project.
//

#ifndef INCLUDED_IEXMATHFLOATEXC_H
#define INCLUDED_IEXMATHFLOATEXC_H

#include "IexExport.h"
#include "IexNamespace.h"

#include "IexMathIeeeExc.h"

IEX_INTERNAL_NAMESPACE_HEADER_ENTER

//-------------------------------------------------------------
// Function mathExcOn() defines which floating point exceptions
// will be trapped and converted to C++ exceptions.
//-------------------------------------------------------------

IEX_EXPORT
void mathExcOn (int when = (IEEE_OVERFLOW | IEEE_DIVZERO | IEEE_INVALID));

//----------------------------------------------------------------------
// Function getMathExcOn() tells you for which floating point exceptions
// trapping and conversion to C++ exceptions is currently enabled.
//----------------------------------------------------------------------

IEX_EXPORT
int getMathExcOn ();

//------------------------------------------------------------------------
// A class that temporarily sets floating point exception trapping
// and conversion, and later restores the previous settings.
//
// Example:
//
//      float
//      trickyComputation (float x)
//      {
//          MathExcOn meo (0);          // temporarily disable floating
//                                      // point exception trapping
//
//          float result = ...;         // computation which may cause
//                                      // floating point exceptions
//
//          return result;              // destruction of meo restores
//      }                               // the program's previous floating
//                                      // point exception settings
//------------------------------------------------------------------------

class IEX_EXPORT_TYPE MathExcOn
{
public:
    IEX_EXPORT MathExcOn (int when);
    IEX_EXPORT ~MathExcOn ();
    MathExcOn (const MathExcOn&) = delete;
    MathExcOn& operator= (const MathExcOn&) = delete;
    MathExcOn (MathExcOn&&)                 = delete;
    MathExcOn& operator= (MathExcOn&&) = delete;

    // It is possible for functions to set the exception registers
    // yet not trigger a SIGFPE.  Specifically, the implementation
    // of pow(x, y) we're using can generates a NaN from a negative x
    // and fractional y but a SIGFPE is not generated.
    // This function examimes the exception registers and calls the
    // fpHandler if those registers modulo the exception mask are set.
    // It should be called wherever this class is commonly used where it has
    // been found that certain floating point exceptions are not being thrown.

    IEX_EXPORT void handleOutstandingExceptions ();

private:
    bool _changed;
    int  _saved;
};

IEX_INTERNAL_NAMESPACE_HEADER_EXIT

#endif