Class Disk

java.lang.Object
   |
   +----Disk

public class Disk

extends Object

implements Runnable

You may not change this class.

This disk is slow and ornery. It contains a number of blocks, all BLOCK_SIZE bytes long. All operations occur on individual blocks. You can't modify any more or any less data at a time.

To read or write from the disk, call beginRead() or beginWrite(). Both of these functions will start the action and return immediately. When the action has been completed, a call to Kernel.interrupt() will occur to let you know the Disk is ready for more.

It may take a while for the disk to seek from one block to another. Seek time is proportional to the difference in block number.

Warning: Don't call beginRead() or beginWrite() while the disk is busy! If you don't treat the Disk gently, the system will crash! (Just like a real machine!)

Author:

Douglas Thain (thain@cs.wisc.edu)

See Also:

Kernel

BLOCK_SIZE

Disk(int)

Create a new Disk.

beginRead(int, byte[])

Start a new read operation.

beginWrite(int, byte[])

Start a new write operation.

getSize()

Get the size of the disk

run()

Do not call this function.

 public static final int BLOCK_SIZE

 public Disk(int b)

Create a new Disk.

Parameters:

b - The number of blocks on the disk.

 public int getSize()

Get the size of the disk

Returns:

The number of blocks in this disk.

 public synchronized void beginRead(int b,
                                    byte d[])

Start a new read operation.

Parameters:

b - The block number to read from.

d - The data area to write to.

 public synchronized void beginWrite(int b,
                                     byte d[])

Start a new write operation.

Parameters:

b - The block to write to.

d - The data area to read from.

 public void run()

Do not call this function.