import java.util.*;import java.io.*;class Disk {    // the size in bytes of each disk block    public final static int BLOCK_SIZE = 512;    // the number of disk blocks in the system    public final static int NUM_BLOCKS = 1000;    // the number of pointers in a disk block to other disk blocks    public final static int POINTERS_PER_BLOCK = (BLOCK_SIZE/4);    // the number of reads and writes to the file system    private int readCount = 0;	private int writeCount = 0;	// the file representing the simulated  disk	private File fileName;	private RandomAccessFile disk;	// read in the file representing the simulated disk	public Disk() {		try {			fileName = new File("DISK");			disk = new RandomAccessFile(fileName, "rw");		}		catch (IOException e) {			System.err.println ("Unable to start the disk");			System.exit(1);		}	}	private void seek(int blocknum) throws IOException {		if (blocknum < 0 || blocknum >= NUM_BLOCKS) 			throw new RuntimeException ("Attempt to read block " +					       blocknum + " is out of range");		disk.seek((long)(blocknum * BLOCK_SIZE));	}	/** 	 * read from blockNum into a byte buffer	 */	public void read(int blocknum, byte[] buffer) {		if (buffer.length != BLOCK_SIZE) 			throw new RuntimeException(				"Read: bad buffer size " + buffer.length);		try {			seek(blocknum);			disk.read(buffer);		}		catch (IOException e) {			System.err.println(e);			System.exit(1);		}		readCount++;	} 	public void read(int blocknum, SuperBlock block) {		try {			seek(blocknum);			block.size = disk.readInt();			block.iSize = disk.readInt();			block.freeList = disk.readInt();		}		catch (EOFException e) {			if (blocknum != 0) {				System.err.println(e);				System.exit(1);			}			block.size = block.iSize = block.freeList = 0;		}		catch (IOException e) {			System.err.println(e);			System.exit(1);		}		readCount++;	} 	public void read(int blocknum, InodeBlock block) {		try {			seek(blocknum);			for (int i=0; i<block.node.length; i++) {				block.node[i].flags = disk.readInt();				block.node[i].owner = disk.readInt();				//block.node[i].size = disk.readInt();				block.node[i].fileSize = disk.readInt();				for (int j=0; j<13; j++)					block.node[i].pointer[j] = disk.readInt();			}		}		catch (IOException e) {			System.err.println(e);			System.exit(1);		}		readCount++;	} 			public void read(int blocknum, IndirectBlock block) {		try {			seek(blocknum);			for (int i=0; i<block.pointer.length; i++)				block.pointer[i] = disk.readInt();		}		catch (IOException e) {			System.err.println(e);			System.exit(1);		}		readCount++;	} 		/** 	 * Write from the buffer to to blockNum 		 */	public void write(int blocknum, byte[] buffer) {		if (buffer.length != BLOCK_SIZE) 			throw new RuntimeException(				"Write: bad buffer size " + buffer.length);		try {			seek(blocknum);			disk.write(buffer);		}		catch (IOException e) {			System.err.println(e);			System.exit(1);		}		writeCount++;	}	public void write(int blocknum, SuperBlock block) {		try {			seek(blocknum);			disk.writeInt(block.size);			disk.writeInt(block.iSize);			disk.writeInt(block.freeList);		}		catch (IOException e) {			System.err.println(e);			System.exit(1);		}		writeCount++;	} 	public void write(int blocknum, InodeBlock block) {		try {			seek(blocknum);			for (int i=0; i<block.node.length; i++) {				disk.writeInt(block.node[i].flags);				//disk.writeInt(block.node[i].owner);				//disk.writeInt(block.node[i].size);				disk.writeInt(block.node[i].fileSize);				for (int j=0; j<13; j++)					disk.writeInt(block.node[i].pointer[j]);			}		}		catch (IOException e) {			System.err.println(e);			System.exit(1);		}		writeCount++;	} 			public void write(int blocknum, IndirectBlock block) {		try {			seek(blocknum);			for (int i=0; i<block.pointer.length; i++)				disk.writeInt(block.pointer[i]);		}		catch (IOException e) {			System.err.println(e);			System.exit(1);		}		writeCount++;	} 			public void stop(boolean removeFile) {		//System.out.println (toString());		System.out.println (generateStats());		if (removeFile)			fileName.delete();	}	public void stop() {		stop(true);	}	/**	 * Outputs statistics from the file system.	 */	//public String toString() {	public String generateStats() {		return ("DISK: Read count: " + readCount + " Write count: " + 			writeCount);	}}