/*
 * AppleCommander - An Apple ][ image utility.
 * Copyright (C) 2003 by Robert Greene
 * robgreene at users.sourceforge.net
 *
 * This program is free software; you can redistribute it and/or modify it 
 * under the terms of the GNU General Public License as published by the 
 * Free Software Foundation; either version 2 of the License, or (at your 
 * option) any later version.
 *
 * This program 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 General Public License 
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along 
 * with this program; if not, write to the Free Software Foundation, Inc., 
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package com.webcodepro.applecommander.storage.physical;

import com.webcodepro.applecommander.storage.Disk;
import com.webcodepro.applecommander.storage.StorageBundle;
import com.webcodepro.applecommander.util.TextBundle;

/**
 * Supports disk images stored in ProDOS physical order.
 * <p> 
 * @author Rob Greene (RobGreene@users.sourceforge.net)
 */
public class ProdosOrder extends ImageOrder {
	private TextBundle textBundle = StorageBundle.getInstance();
	/**
	 * This table contains the block offset for a particular DOS sector.
	 */
	private static final int[] blockInterleave = { 
		0, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 7 
	};
	/**
	 * Defines the location within a block in which the DOS sector resides.
	 * (0 = 0-255 and 1 = 256-511.)
	 */
	private static final int[] blockOffsets = { 
		0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1 
	};

	/**
	 * Construct a ProdosOrder.
	 */
	public ProdosOrder(ByteArrayImageLayout diskImageManager) {
		super(diskImageManager);
	}
	
	/**
	 * Indicates that this device is block ordered.
	 */
	public boolean isBlockDevice() {
		return true;
	}
	
	/**
	 * Indicates that this device is track and sector ordered.
	 */
	public boolean isTrackAndSectorDevice() {
		return false;
	}

	/**
	 * Read the block from the disk image.
	 * Note: Defined in terms of reading sectors.
	 */
	public byte[] readBlock(int block) {
		return readBytes(block * Disk.BLOCK_SIZE, Disk.BLOCK_SIZE);
	}
	
	/**
	 * Write the block to the disk image.
	 * Note: Defined in terms of reading sectors.
	 */
	public void writeBlock(int block, byte[] data) {
		writeBytes(block * Disk.BLOCK_SIZE, data);
	}

	/**
	 * Retrieve the specified sector.
	 */
	public byte[] readSector(int track, int sector) throws IllegalArgumentException {
		int block = track * 8 + blockInterleave[sector];
		byte[] blockData = readBlock(block);
		int offset = blockOffsets[sector];
		byte[] sectorData = new byte[Disk.SECTOR_SIZE];
		System.arraycopy(blockData, offset * Disk.SECTOR_SIZE, 
			sectorData, 0, Disk.SECTOR_SIZE); 
		return sectorData;
	}
	
	/**
	 * Write the specified sector.
	 */
	public void writeSector(int track, int sector, byte[] bytes) throws IllegalArgumentException {
		int block = track * 8 + blockInterleave[sector];
		byte[] blockData = readBlock(block);
		int offset = blockOffsets[sector];
		System.arraycopy(bytes, 0, blockData, offset * Disk.SECTOR_SIZE, bytes.length);
		writeBlock(block, blockData);
	}

	/**
	 * Return the name of this image order.
	 */
	public String getName() {
		return textBundle.get("ProdosOrder.OrderName"); //$NON-NLS-1$ 
	}
}