vtkExtensionsRNG.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * $Id: vtkExtensionsRNG.h,v 1.3 2004/08/10 07:37:21 xpxqx Exp $
 *
 * Copyright (c) 2004 Sean McInerney
 * All rights reserved.
 *
 * See Copyright.txt or http://vtkextensions.sourceforge.net/Copyright.html
 * for details.
 *
 *    This software is distributed WITHOUT ANY WARRANTY; without even 
 *    the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
 *    PURPOSE.  See the above copyright notice for more information.
 *
 */
#ifndef VTK_EXTENSIONS_RNG_H_
#  define VTK_EXTENSIONS_RNG_H_
#  include "vtkExtensionsCommonConfigure.h" // vtkExtensions configuration
#  include "vtkExtensionsTypes.h"           // vtkExtensions types
// VTK Common
#  include "vtkCriticalSection.h"           // member
#  include "vtkObject.h"

VTK_EXTENSIONS_NAMESPACE_BEGIN

class VTK_EXTENSIONS_COMMON_EXPORT vtkExtensionsRNG : public vtkObject
{
public:
  static vtkExtensionsRNG* New (void);
  vtkTypeRevisionMacro (vtkExtensionsRNG, vtkObject);
  void PrintSelf (ostream&, vtkIndent);

  void          GetRandomBytes (void* aBuffer, int aByteCount);

protected:
  vtkExtensionsRNG (void);
  ~vtkExtensionsRNG();

  //BTX
  // Syncronization primatives.
  vtkSimpleCriticalSection      CriticalSection;
  // RNG.
  vtkUint32Type Q[1024]; // seeds
  vtkUint32Type C;
  vtkUint32Type I;

  void          CMWC (vtkUint32Type& aResult);
  //ETX

private:
  vtkExtensionsRNG (const vtkExtensionsRNG&);
  void operator= (const vtkExtensionsRNG&);
};

inline void
vtkExtensionsRNG::CMWC (vtkUint32Type& aResult)
{
  unsigned long long    t, a = 123471786LL;
  vtkUint32Type         x, r = VTK_EXTENSIONS_UINT32(0xFFFFFFFE);

  this->I = (this->I + 1) & 1023;
  t = a * this->Q[this->I] + this->C;
  this->C = (t>>32);
  x = t + this->C;
  if (x < this->C) { x++; this->C++; }

  aResult = (this->Q[this->I] = r - x);
}

VTK_EXTENSIONS_NAMESPACE_END

#endif /* VTK_EXTENSIONS_RNG_H_ */
/*
 * End of: $Id: vtkExtensionsRNG.h,v 1.3 2004/08/10 07:37:21 xpxqx Exp $.
 *
 */

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