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Filename : IexMathFloatExc.h
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///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2002, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
// 
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// *       Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// *       Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// *       Neither the name of Industrial Light & Magic nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission. 
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
///////////////////////////////////////////////////////////////////////////



#ifndef INCLUDED_IEXMATHFLOATEXC_H
#define INCLUDED_IEXMATHFLOATEXC_H

#ifndef IEXMATH_EXPORT_H
#define IEXMATH_EXPORT_H

#if defined(OPENEXR_DLL)
    #if defined(IEX_EXPORTS)
    #define IEXMATH_EXPORT __declspec(dllexport)
    #else
    #define IEXMATH_EXPORT __declspec(dllimport)
    #endif
    #define IEXMATH_EXPORT_CONST
#else
    #define IEXMATH_EXPORT
    #define IEXMATH_EXPORT_CONST const
#endif

#endif

#include "IexNamespace.h"
#include "IexMathExc.h"
//#include <IexBaseExc.h>
#include "IexMathIeeeExc.h"

IEX_INTERNAL_NAMESPACE_HEADER_ENTER


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

IEXMATH_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.
//----------------------------------------------------------------------

IEXMATH_EXPORT
int getMathExcOn();


//------------------------------------------------------------------------
// A classs 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 IEXMATH_EXPORT MathExcOn
{
  public:

    MathExcOn (int when)
	:
	_changed (false)
    {
	_saved = getMathExcOn(); 

	if (_saved != when)
	{
	    _changed = true;
	    mathExcOn (when);
	}
    }

    ~MathExcOn ()
    {
	if (_changed)
	    mathExcOn (_saved);
    }

    // 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.

    void handleOutstandingExceptions();

  private:

    bool                        _changed;
    int				_saved;
};


IEX_INTERNAL_NAMESPACE_HEADER_EXIT

#endif