// 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 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\debug\crashMonitor\src\scmchksum.cpp

// 

//

/**

 @file

 @internalTechnology

*/

#include <scmdatatypes.h>

namespace Debug

	{	

	/**

	 * Constructor

	 */

	TScmChecksum::TScmChecksum()

	: iLength(0)	

	, iSum(0)

	, iZeroCount(0)

		{	

		}

	/**

	 * ChecksumBlock - calculate checksum values for given data

	 * @param aData - the data to checksum

	 * @param aLen - the length of the data to checksum

	 * @return void

	 */

	void TScmChecksum::ChecksumBlock(const TUint8* aData, TUint aLen)

		{		

		/**

		 * 

		 * Note there is Symbian CRC implementation to be found in the following

		 * \src\cedar\generic\tools\e32tools\elf2e32\source\checksum.h

		 * \src\cedar\generic\tools\e32tools\elf2e32\source\checksum.cpp

		 * this however may be no good to us

		 * as we need to produce a single checksum even though the entire data may be

		 * read in different size blocks - and the entire data may not be available

		 * (the comm port requirement is for read only )

		 * If we do however want to use the CRC then this is the place to insert the code

		 */		

		if(!aData)

			{

			return;

			}

		for(TUint i=0;i<aLen;i++)

			{

			TUint8 val = *(aData+i);

			iLength++;

			if(val == 0)

				{

				iZeroCount++;

				}

			else

				{

				iSum += val;

				}			

			}		

		}

	/**

	 * ChecksumBlock - calculate checksum values for given data

	 * @param aData - descriptor containing the data to checksum

	 * @return void

	 */

	void TScmChecksum::ChecksumBlock(const TDesC8& aDes)

		{

		ChecksumBlock(aDes.Ptr(), aDes.Length());

		}

	/**

	 * ChecksumBlock - operator ==

	 * @param aOther - the TScmChecksum to compare too

	 * @return ETrue is objects match - otherwise EFalse

	 */

	TBool TScmChecksum::operator == (const TScmChecksum& aOther) const

		{

		return (iLength == aOther.iLength && iSum == aOther.iSum && iZeroCount == aOther.iZeroCount);

		}

	/**

	 * ChecksumBlock - operator !=

	 * @param aOther - the TScmChecksum to compare too

	 * @return EFalse if objects match - otherwise ETrue

	 */

	TBool TScmChecksum::operator != (const TScmChecksum& aOther) const

		{

		return !(*this == aOther);

		}

	/**

	 * GetSize 

	 * @return size of this object when streamed in bytes

	 */

	TInt TScmChecksum::GetSize() const

 		{

 		return 12;

 		}

	/**

	 * Serialize - writes this object to the supplied byte stream

	 * @param aItem -  aWriter - the TByteStreamWriter that will be written to

	 * @return One of the OS wide codes

	 */

	TInt TScmChecksum::Serialize(TByteStreamWriter& aWriter)

		{	

		TInt startPos = aWriter.CurrentPosition();

		aWriter.WriteInt(iLength);

		aWriter.WriteInt(iSum);

		aWriter.WriteInt(iZeroCount);

		TInt sizeWritten = aWriter.CurrentPosition() - startPos;

		if(sizeWritten != GetSize())

			{

			// error between actual size & real size in data

			CLTRACE("TScmChecksum serialization size error");	

			return KErrCorrupt;

			}

		return KErrNone;

		}

	/**

	 * Deserialize - read this objects state from the supplied byte stream

	 * @param aItem -  aReader - the TByteStreamReader that will be read from

	 * @return One of the OS wide codes

	 */

	TInt TScmChecksum::Deserialize(TByteStreamReader& aReader)

		{

		TInt startPos = aReader.CurrentPosition();

		// do we need a version check here - will it change ?

		iLength = aReader.ReadInt();	

		iSum = aReader.ReadInt();

		iZeroCount = aReader.ReadInt();	

		TInt sizeRead = aReader.CurrentPosition() - startPos;

		if(sizeRead != GetSize())

			{

			// error between actual size & real size in data

			CLTRACE("TScmChecksum Deserialization size error");	

			return KErrCorrupt;

			}

		return KErrCorrupt;

		}

	void TScmChecksum::Reset()

		{

		iLength = iSum = iZeroCount = 0;	

		}		

	}

//eof