// Copyright (c) 1995-2009 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:

 // e32\euser\maths\um_sqrt.cpp

 // Square root.

 // 

 //

 #include "um_std.h"

 #if defined(__USE_VFP_MATH) && !defined(__CPU_HAS_VFP)

 #error	__USE_VFP_MATH was defined but not __CPU_HAS_VFP - impossible combination, check variant.mmh 

 #endif

 #ifndef __USE_VFP_MATH

 #ifndef __REALS_MACHINE_CODED__

 LOCAL_D const TUint32 KConstAdata[] = {0x00000000,0xD5A9A805,0x7FFD0000};

 LOCAL_D const TUint32 KConstBdata[] = {0x00000000,0x9714B9CB,0x7FFE0000};

 LOCAL_D const TUint32 Sqr2Invdata[] = {0xF9DE6484,0xB504F333,0x7FFE0000};		// 1/sqr2

 EXPORT_C TInt Math::Sqrt(TReal& aTrg,const TReal &aSrc)

 /**

 Calculates the square root of a number.

 @param aTrg A reference containing the result. 

 @param aSrc The number whose square-root is required.

 @return KErrNone if successful, otherwise another of

         the system-wide error codes. 

 */

 //

 // Fast sqrt routine. See Software manual by W.J.Cody & W.Waite Chapter 4.

 //

 	{

 	const TRealX& KConstA=*(const TRealX*)KConstAdata;

 	const TRealX& KConstB=*(const TRealX*)KConstBdata;

 	const TRealX& Sqr2Inv=*(const TRealX*)Sqr2Invdata;

 	TRealX x;

 	TInt r=x.Set(aSrc);

 	if (x.IsZero())

 		{

 		aTrg=aSrc;

 		return(KErrNone);

 		}   

 	if (r==KErrArgument || x.iSign&1)

 		{

 		SetNaN(aTrg);

 		return(KErrArgument);

 		}

 	if (r==KErrOverflow)	// positive infinity

 		{

 		aTrg=aSrc;

 		return(r);

 		}

 	TInt n=x.iExp-0x7FFE;

 	x.iExp=0x7FFE;

 	TRealX y=KConstB*x+KConstA;

 	y=y+(x/y);

 	y.iExp--;

 	y=y+(x/y);

 	y.iExp--;

 	y=y+(x/y);

 	y.iExp--;

 	if (n&1)

 		{

 		y*=Sqr2Inv;

 		n++;

 		}

 	y.iExp=TUint16(TInt(y.iExp)+(n>>1));

 	return y.GetTReal(aTrg);

 	}

 #endif

 #endif // !__USE_VFP_MATH - VFP version is in assembler