// 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