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/*
* Copyright (C) 2003-2009 JNode.org
* 2009,2010 Matthias Treydte <mt@waldheinz.de>
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; If not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package de.waldheinz.fs.fat;
/**
* Enumerates the different entry sizes of 12, 16 and 32 bits for the different
* FAT flavours.
*
* @author Ewout Prangsma <epr at jnode.org>
* @author Matthias Treydte <waldheinz at gmail.com>
*/
public enum FatType {
/**
* Represents a 12-bit file allocation table.
*/
FAT12((1 << 12) - 16, 0xFFFL, 1.5f, "FAT12 ") { //NOI18N
@Override
long readEntry(byte[] data, int index) {
final int idx = (int) (index * 1.5);
final int b1 = data[idx] & 0xFF;
final int b2 = data[idx + 1] & 0xFF;
final int v = (b2 << 8) | b1;
if ((index % 2) == 0) {
return v & 0xFFF;
} else {
return v >> 4;
}
}
@Override
void writeEntry(byte[] data, int index, long entry) {
final int idx = (int) (index * 1.5);
if ((index % 2) == 0) {
data[idx] = (byte) (entry & 0xFF);
data[idx + 1] = (byte) ((entry >> 8) & 0x0F);
} else {
data[idx] |= (byte) ((entry & 0x0F) << 4);
data[idx + 1] = (byte) ((entry >> 4) & 0xFF);
}
}
},
/**
* Represents a 16-bit file allocation table.
*/
FAT16((1 << 16) - 16, 0xFFFFL, 2.0f, "FAT16 ") { //NOI18N
@Override
long readEntry(byte[] data, int index) {
final int idx = index << 1;
final int b1 = data[idx] & 0xFF;
final int b2 = data[idx + 1] & 0xFF;
return (b2 << 8) | b1;
}
@Override
void writeEntry(byte[] data, int index, long entry) {
final int idx = index << 1;
data[idx] = (byte) (entry & 0xFF);
data[idx + 1] = (byte) ((entry >> 8) & 0xFF);
}
},
/**
* Represents a 32-bit file allocation table.
*/
FAT32((1 << 28) - 16, 0xFFFFFFFFL, 4.0f, "FAT32 ") { //NOI18N
@Override
long readEntry(byte[] data, int index) {
final int idx = index * 4;
final long l1 = data[idx] & 0xFF;
final long l2 = data[idx + 1] & 0xFF;
final long l3 = data[idx + 2] & 0xFF;
final long l4 = data[idx + 3] & 0xFF;
return (l4 << 24) | (l3 << 16) | (l2 << 8) | l1;
}
@Override
void writeEntry(byte[] data, int index, long entry) {
final int idx = index << 2;
data[idx] = (byte) (entry & 0xFF);
data[idx + 1] = (byte) ((entry >> 8) & 0xFF);
data[idx + 2] = (byte) ((entry >> 16) & 0xFF);
data[idx + 3] = (byte) ((entry >> 24) & 0xFF);
}
};
private final long minReservedEntry;
private final long maxReservedEntry;
private final long eofCluster;
private final long eofMarker;
private final long bitMask;
private final int maxClusters;
private final String label;
private final float entrySize;
private FatType(int maxClusters,
long bitMask, float entrySize, String label) {
this.minReservedEntry = (0xFFFFFF0L & bitMask);
this.maxReservedEntry = (0xFFFFFF6L & bitMask);
this.eofCluster = (0xFFFFFF8L & bitMask);
this.eofMarker = (0xFFFFFFFL & bitMask);
this.entrySize = entrySize;
this.label = label;
this.maxClusters = maxClusters;
this.bitMask = bitMask;
}
abstract long readEntry(byte[] data, int index);
abstract void writeEntry(byte[] data, int index, long entry);
/**
* Returns the maximum number of clusters this file system can address.
*
* @return the maximum cluster count supported
*/
long maxClusters() {
return this.maxClusters;
}
/**
* Returns the human-readable FAT name string as written to the
* {@link com.meetwise.fs.BootSector}.
*
* @return the boot sector label for this FAT type
*/
String getLabel() {
return this.label;
}
boolean isReservedCluster(long entry) {
return ((entry >= minReservedEntry) && (entry <= maxReservedEntry));
}
boolean isEofCluster(long entry) {
return (entry >= eofCluster);
}
long getEofMarker() {
return eofMarker;
}
float getEntrySize() {
return entrySize;
}
long getBitMask() {
return bitMask;
}
}
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