/*

* Copyright (c) 2006-2009 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: 

* Cluster class used to allocate cluster numbers for directory entries 

* and while writing file contents. And it is responsible to create the 

* MAP of content starting cluster to ending cluster which can be used 

* to generate FAT table. Since the cluster number is unique all over the

* filesystem component, this class is designed as singleton class.

* @internalComponent

* @released

*

*/

#include "cluster.h"

//Initialize the Static CCluster instance pointer

CCluster* CCluster::iClusterInstance = NULL;

/**

Static function which is used to instantiate and return the address of CCluster class.

@internalComponent

@released

@param aClusterSize - single cluster size in Bytes

@param aTotalNumberOfClusters - Maximum number of clusters

@return - returns the instance of CCluster class

*/

CCluster* CCluster::Instance(unsigned int aClusterSize,unsigned int aTotalNumberOfClusters) 

{

	if (iClusterInstance == NULL)  // is it the first call?

    {  

		// create sole instance

		iClusterInstance = new CCluster(aClusterSize, aTotalNumberOfClusters);

    }

    return iClusterInstance; // address of sole instance

}

/**

Destructor: Clears the clusters per entry map

@internalComponent

@released

*/

CCluster::~CCluster ()

{

	iClustersPerEntry.clear();

	iClusterInstance = NULL;

}

/**

Constructor Receives inputs from dirregion Class and initializes the class variables

@internalComponent

@released

@param aClusterSize - Size of every Cluster

@param aTotalNumberOfClusters - maximum number of clusters allowed for current FAT image

*/

CCluster::CCluster(unsigned int aClusterSize, unsigned int aTotalNumberOfClusters)

				   :iClusterSize(aClusterSize),iTotalNumberOfClusters(aTotalNumberOfClusters)

{

	iRootClusterNumber = KRootClusterNumber;

	iCurrentClusterNumber = iRootClusterNumber;

}

/**

Function to return the current cluster number

@internalComponent

@released

@return - returns the current cluster number

*/

unsigned int CCluster::GetCurrentClusterNumber() const

{

	return iCurrentClusterNumber;

}

/** 

Function to decrement the current cluster number

@internalComponent

@released

*/

void CCluster::DecrementCurrentClusterNumber()

{

	--iCurrentClusterNumber;

}

/**

Function to get the High word of Current cluster number

@internalComponent

@released

@return - returns the 16 bit HIGH word

*/

unsigned short int CCluster::GetHighWordClusterNumber() const

{

	return (unsigned short)(iCurrentClusterNumber >> KBitShift16);

}

/**

Function to get the Low word of Current cluster number

@internalComponent

@released

@return - returns the 16 bit LOW word

*/

unsigned short int CCluster::GetLowWordClusterNumber() const

{

	return (unsigned short)(iCurrentClusterNumber & KHighWordMask);

}

/**

Function responsible to 

1. Increment the current Cluster Number 

2. Throw the error "image size too big" if the allocated clusters count exceeds total

number of available clusters.

@internalComponent

@released

*/

void CCluster::UpdateNextAvailableClusterNumber()

{

	if(iCurrentClusterNumber >= iTotalNumberOfClusters)

	{

    	throw ErrorHandler(IMAGESIZETOOBIG,"Occupied number of clusters count exceeded than available clusters",__FILE__,__LINE__);

	}

	++iCurrentClusterNumber;

}

/**

Function to Return the cluster size

@internalComponent

@released

@return the cluster size

*/

unsigned int CCluster::GetClusterSize() const

{

	return iClusterSize;

}

/**

Function Creates mapping between starting cluster number (where data starts) and 

the sub sequent cluster numbers (where the data extends).

@internalComponent

@released

@param aStartingClusterNumber - Cluster number where the data starts

@param aPairClusterNumber - Cluster number where the data extends

*/

void CCluster::CreateMap(unsigned int aStartingClusterNumber,unsigned int aPairClusterNumber)

{

	iClustersPerEntry.insert(make_pair(aStartingClusterNumber,aPairClusterNumber));

}

/**

Function to get Clusters per Entry MAP container.

@internalComponent

@released

@return - returns the CLusters per entry container

*/

TClustersPerEntryMap* CCluster::GetClustersPerEntryMap()

{

	return &iClustersPerEntry;

}