/*

 * Copyright (c) 2003-2009 Nokia Corporation and/or its subsidiary(-ies).

 * All rights reserved.

 * This component and the accompanying materials are made available

 * under the terms of the License "Eclipse Public License v1.0"

 * which accompanies this distribution, and is available

 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

 *

 * Initial Contributors:

 * Nokia Corporation - initial contribution.

 *

 * Contributors:

 *

 * Description: 

 * TWindowSlider class implementation

 *

 */

 /**

  @file 

  @internalComponent

 */

 #ifndef __WINDOWSLIDER_H__

 #define __WINDOWSLIDER_H__

 #include <e32std.h>

 class TInteger; 

 /** Utility class used by our fast exponentiation routines.\n\n

  * See HAC 14.85 for an explanation of how window sliding helps speed things up.

  * @internalComponent

  */

 class TWindowSlider

 {

 public:

 	/** 

 	 * @param aExp The exponent you are using.

 	 * @param aWindowSize The window size.  Leave as default value for the

 	 * constructor to pick a window size appropriate for the given aExp

 	 * @internalComponent

 	 */

 	TWindowSlider(const TInteger& aExp, TUint aWindowSize=0);

 	/**

 	 * Finds the next "window" as defined by HAC 14.85.  The actual bitstring

 	 * value is in iValue and it's length in iLength.  These remain valid until

 	 * the next call to FindNextWindow()

 	 */

 	void FindNextWindow(TUint aBegin);

 	inline TUint WindowSize(void) {return iSize;}

 	inline TUint Value(void) {return iValue;}

 	inline TUint Length(void) {return iLength;}

 private:

 	const TInteger& iExp; ///the exponent all this is being calculated on

 	TUint iSize;  ///The size of the sliding window

 	TUint iValue; ///the value found by the most recent FindNextWindow() call

 	TUint iLength;///the bit length of the iValue

 };

 #endif