1 /*

     2 * Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

     5 * under the terms of the License "Eclipse Public License v1.0"

     6 * which accompanies this distribution, and is available

     7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description: 

    15 * Cluster class used to allocate cluster numbers for directory entries 

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

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

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

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

    20 * @internalComponent

    21 * @released

    22 *

    23 */

    24 

    25 

    26 #include "cluster.h"

    27 

    28 

    29 //Initialize the Static CCluster instance pointer

    30 CCluster* CCluster::iClusterInstance = NULL;

    31 

    32 /**

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

    34 

    35 @internalComponent

    36 @released

    37 

    38 @param aClusterSize - single cluster size in Bytes

    39 @param aTotalNumberOfClusters - Maximum number of clusters

    40 @return - returns the instance of CCluster class

    41 */

    42 

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

    44 {

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

    46     {  

    47 		// create sole instance

    48 		iClusterInstance = new CCluster(aClusterSize, aTotalNumberOfClusters);

    49     }

    50     return iClusterInstance; // address of sole instance

    51 }

    52 

    53 /**

    54 Destructor: Clears the clusters per entry map

    55 

    56 @internalComponent

    57 @released

    58 */

    59 CCluster::~CCluster ()

    60 {

    61 	iClustersPerEntry.clear();

    62 	iClusterInstance = NULL;

    63 }

    64 

    65 

    66 /**

    67 Constructor Receives inputs from dirregion Class and initializes the class variables

    68 

    69 @internalComponent

    70 @released

    71 

    72 @param aClusterSize - Size of every Cluster

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

    74 */

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

    76 				   :iClusterSize(aClusterSize),iTotalNumberOfClusters(aTotalNumberOfClusters)

    77 {

    78 	iRootClusterNumber = KRootClusterNumber;

    79 	iCurrentClusterNumber = iRootClusterNumber;

    80 }

    81 

    82 /**

    83 Function to return the current cluster number

    84 

    85 @internalComponent

    86 @released

    87 

    88 @return - returns the current cluster number

    89 */

    90 unsigned int CCluster::GetCurrentClusterNumber() const

    91 {

    92 	return iCurrentClusterNumber;

    93 }

    94 

    95 /** 

    96 Function to decrement the current cluster number

    97 

    98 @internalComponent

    99 @released

   100 */

   101 void CCluster::DecrementCurrentClusterNumber()

   102 {

   103 	--iCurrentClusterNumber;

   104 }

   105 

   106 /**

   107 Function to get the High word of Current cluster number

   108 

   109 @internalComponent

   110 @released

   111 

   112 @return - returns the 16 bit HIGH word

   113 */

   114 unsigned short int CCluster::GetHighWordClusterNumber() const

   115 {

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

   117 }

   118 

   119 /**

   120 Function to get the Low word of Current cluster number

   121 

   122 @internalComponent

   123 @released

   124 

   125 @return - returns the 16 bit LOW word

   126 */

   127 unsigned short int CCluster::GetLowWordClusterNumber() const

   128 {

   129 	return (unsigned short)(iCurrentClusterNumber & KHighWordMask);

   130 }

   131 

   132 

   133 /**

   134 Function responsible to 

   135 1. Increment the current Cluster Number 

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

   137 number of available clusters.

   138 

   139 @internalComponent

   140 @released

   141 */

   142 void CCluster::UpdateNextAvailableClusterNumber()

   143 {

   144 	if(iCurrentClusterNumber >= iTotalNumberOfClusters)

   145 	{

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

   147 	}

   148 	++iCurrentClusterNumber;

   149 }

   150 

   151 /**

   152 Function to Return the cluster size

   153 

   154 @internalComponent

   155 @released

   156 

   157 @return the cluster size

   158 */

   159 unsigned int CCluster::GetClusterSize() const

   160 {

   161 	return iClusterSize;

   162 }

   163 

   164 /**

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

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

   167 

   168 @internalComponent

   169 @released

   170 

   171 @param aStartingClusterNumber - Cluster number where the data starts

   172 @param aPairClusterNumber - Cluster number where the data extends

   173 */

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

   175 {

   176 	iClustersPerEntry.insert(std::make_pair(aStartingClusterNumber,aPairClusterNumber));

   177 }

   178 

   179 /**

   180 Function to get Clusters per Entry MAP container.

   181 

   182 @internalComponent

   183 @released

   184 

   185 @return - returns the CLusters per entry container

   186 */

   187 

   188 TClustersPerEntryMap* CCluster::GetClustersPerEntryMap()

   189 {

   190 	return &iClustersPerEntry;

   191 }