Class FastDisk

Object
  Disk
      FastDisk

All Implemented Interfaces:

Runnable

public class FastDisk

extends Disk

A new and improved Disk. You may not change this class.

This disk is so much faster than the previous model that read and write operations appear to finish in no time. Because disk is so fast, beginRead and beginWrite wait for the operation to finish rather than causing a CPU interrupt when they complete.

See Also:

Disk, Kernel

Nested Class Summary

Nested classes inherited from class Disk

Disk.DiskException

Field Summary

Fields inherited from class Disk

BLOCK_SIZE, busy, currentBlock, data, DISK_SIZE, readCount, targetBlock, writeCount

Constructor Summary

FastDisk(int size)
Creates a new FastDisk.

Method Summary

void	beginRead(int blockNumber, byte[] buffer) Deprecated. Do not use this method. Use read instead.
void	beginWrite(int blockNumber, byte[] buffer) Deprecated. Do not use this method. Use read instead.
void	read(int blockNumber, byte[] buffer) Performs a read operation.
void	write(int blockNumber, byte[] buffer) Performs a write operation.

Methods inherited from class Disk

delay, finishOperation, flush, run, waitForRequest

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FastDisk

public FastDisk(int size)

Creates a new FastDisk.

Parameters:

size - the total size of this disk, in blocks.

Method Detail

read

public void read(int blockNumber,
                 byte[] buffer)

Performs a read operation. When this method returns, the operation is complete.

Parameters:

blockNumber - The block number to read from.

buffer - a data area to hold the data read.

See Also:

Disk.beginRead(int, byte[])

write

public void write(int blockNumber,
                  byte[] buffer)

Performs a write operation. When this method returns, the operation is complete.

Parameters:

blockNumber - The block number to write to.

buffer - a data area to hold the data to be written.

See Also:

Disk.beginWrite(int, byte[])

beginRead

public void beginRead(int blockNumber,
                      byte[] buffer)

Deprecated. Do not use this method. Use read instead.

Starts a new read operation.

Overrides:

beginRead in class Disk

Parameters:

blockNumber - The block number to read from.

buffer - A data area to hold the data read. This array must be allocated by the caller and have length of at least BLOCK_SIZE. If it is larger, only the first BLOCK_SIZE bytes of the array will be modified.

beginWrite

public void beginWrite(int blockNumber,
                       byte[] buffer)

Deprecated. Do not use this method. Use read instead.

Starts a new write operation.

Overrides:

beginWrite in class Disk

Parameters:

blockNumber - The block number to write to.

buffer - A data area containing the data to be written. This array must be allocated by the caller and have length of at least BLOCK_SIZE. If it is larger, only the first BLOCK_SIZE bytes of the array will be sent to the disk.