1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/os/security/crypto/weakcryptospi/source/bigint/windowslider.h	Fri Jun 15 03:10:57 2012 +0200
     1.3 @@ -0,0 +1,62 @@
     1.4 +/*
     1.5 +* Copyright (c) 2003-2009 Nokia Corporation and/or its subsidiary(-ies).
     1.6 +* All rights reserved.
     1.7 +* This component and the accompanying materials are made available
     1.8 +* under the terms of the License "Eclipse Public License v1.0"
     1.9 +* which accompanies this distribution, and is available
    1.10 +* at the URL "http://www.eclipse.org/legal/epl-v10.html".
    1.11 +*
    1.12 +* Initial Contributors:
    1.13 +* Nokia Corporation - initial contribution.
    1.14 +*
    1.15 +* Contributors:
    1.16 +*
    1.17 +* Description: 
    1.18 +* TWindowSlider class implementation
    1.19 +*
    1.20 +*/
    1.21 +
    1.22 +
    1.23 +/**
    1.24 + @file 
    1.25 + @internalComponent
    1.26 +*/
    1.27 + 
    1.28 +#ifndef __WINDOWSLIDER_H__
    1.29 +#define __WINDOWSLIDER_H__
    1.30 +
    1.31 +#include <e32std.h>
    1.32 +
    1.33 +class TInteger; 
    1.34 +/** Utility class used by our fast exponentiation routines.\n\n
    1.35 + * See HAC 14.85 for an explanation of how window sliding helps speed things up.
    1.36 + * @internalComponent
    1.37 + */
    1.38 +class TWindowSlider
    1.39 +{
    1.40 +public:
    1.41 +	/** 
    1.42 +	 * @param aExp The exponent you are using.
    1.43 +	 * @param aWindowSize The window size.  Leave as default value for the
    1.44 +	 * constructor to pick a window size appropriate for the given aExp
    1.45 +	 * @internalComponent
    1.46 +	 */
    1.47 +	TWindowSlider(const TInteger& aExp, TUint aWindowSize=0);
    1.48 +	/**
    1.49 +	 * Finds the next "window" as defined by HAC 14.85.  The actual bitstring
    1.50 +	 * value is in iValue and it's length in iLength.  These remain valid until
    1.51 +	 * the next call to FindNextWindow()
    1.52 +	 */
    1.53 +	void FindNextWindow(TUint aBegin);
    1.54 +	inline TUint WindowSize(void) {return iSize;}
    1.55 +	inline TUint Value(void) {return iValue;}
    1.56 +	inline TUint Length(void) {return iLength;}
    1.57 +
    1.58 +private:
    1.59 +	const TInteger& iExp; ///the exponent all this is being calculated on
    1.60 +	TUint iSize;  ///The size of the sliding window
    1.61 +	TUint iValue; ///the value found by the most recent FindNextWindow() call
    1.62 +	TUint iLength;///the bit length of the iValue
    1.63 +};
    1.64 +
    1.65 +#endif