// Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies).

// All rights reserved.

// This component and the accompanying materials are made available

// under the terms of "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:

// System

// 

//

/**

 @file

 @internalTechnology

*/

#include <e32base.h>

#include <e32math.h>

// Component

#include "netpmutils.h"

/**

Constants used in encoding of uncertainty data

@see CSuplStart::Uncertainty()

@see CSuplStart::UncertaintyAltitude()

*/

const TReal KLbsLogOnePointOne = 0.095310179804324860043952123280765;

const TReal KLbsLogOnePointZeroTwoFive = 0.02469261259037150101430767543669;

const TInt  KLbsMaxUncert = 127;

/**

 * TODO: update asn1 code to use this version and delete the CSuplMessageBase version?

Uncertainty()

Converts a minumum accuracy value in meters to an uncertainty value K as 

described in 3GPP 23.032 (Universal Geographical Area Description) section 6.2.

r = C((1+x)^K - 1)

where r = distance in meters

      C = 10

      x = 0.1

      K = uncertainty value

hence K = ln(r/C + 1) / ln(1.1)

@param aDistance - distance measurement in meters

@return uncertainty value K

*/

EXPORT_C TInt NetPmUtils::Uncertainty(const TReal32& aDistance)

	{

	TReal uncert;

	Math::Ln(uncert,  (aDistance/10) + 1 );

	uncert /= KLbsLogOnePointOne;

	if (uncert>KLbsMaxUncert)

		{

		uncert = KLbsMaxUncert;

		}

	// round to nearest whole number

	TReal uncertRounded;

	Math::Round(uncertRounded, uncert, 0);

	return (TInt)uncertRounded;

	}

/**

UncertaintyAltitude()

Converts a minumum accuracy value in meters to an uncertainty altitude value K as 

described in 3GPP 23.032 (Universal Geographical Area Description) section 6.4.

r = C((1+x)^K - 1)

where r = distance in meters

      C = 45

      x = 0.1

      K = uncertainty value

hence K = ln(r/C + 1) / ln(1.1)

@param aDistance - altitude accuracy in meters

@return uncertainty altitude value K

*/

EXPORT_C TInt NetPmUtils::UncertaintyAltitude(const TReal32& aDistance)

	{

	TReal uncert;

	Math::Ln(uncert,  (aDistance/45) + 1 );

	uncert /= KLbsLogOnePointZeroTwoFive;

	if (uncert>KLbsMaxUncert)

		{

		uncert = KLbsMaxUncert;

		}

	// round to nearest whole number

	TReal uncertRounded;

	Math::Round(uncertRounded, uncert, 0);

	return (TInt)uncertRounded;

	}

/**

EncodeAltitude()

Converts an value for altiutude to an 15 bit binary coded number N

@param aAltitude - altitude in meters

@return uncertainty altitude value K

*/

EXPORT_C TInt NetPmUtils::EncodeAltitude(const TReal32& aAltitude)

	{

	TInt altEncoded = (TInt)aAltitude;

	if (altEncoded>KLbsMaxAltitude)

		{

		altEncoded = KLbsMaxAltitude;

		}

	return altEncoded;

	}