nachos.machine
Class Packet

java.lang.Object
  |
  +--nachos.machine.Packet

public class Packet

extends Object

A link-layer packet.

See Also:

NetworkLink

Field Summary

byte[]	contents The contents of this packet, excluding the link-layer header.
int	dstLink The address of the destination link of this packet.
static int	headerLength The number of bytes in a link-layer packet header.
static int	linkAddressLimit The upper limit on Nachos link addresses.
static int	maxContentsLength The maximum number of content bytes (not including the header).
static int	maxPacketLength The maximum length, in bytes, of a packet that can be sent or received on the network.
byte[]	packetBytes This packet, as an array of bytes that can be sent on a network.
int	srcLink The address of the source link of this packet.

Constructor Summary

Packet(byte[] packetBytes)
Allocate a new packet using the specified array of bytes received from the network.

Packet(int dstLink, int srcLink, byte[] contents)
Allocate a new packet to be sent, using the specified parameters.

Methods inherited from class java.lang.Object

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

Field Detail

packetBytes

public byte[] packetBytes

This packet, as an array of bytes that can be sent on a network.

dstLink

public int dstLink

The address of the destination link of this packet.

srcLink

public int srcLink

The address of the source link of this packet.

contents

public byte[] contents

The contents of this packet, excluding the link-layer header.

headerLength

public static final int headerLength

The number of bytes in a link-layer packet header. The header is formatted as follows:

offset	size	value
0	1	network ID (collision detecting)
1	1	destination link address
2	1	source link address
3	1	length of contents

maxPacketLength

public static final int maxPacketLength

The maximum length, in bytes, of a packet that can be sent or received on the network.

maxContentsLength

public static final int maxContentsLength

The maximum number of content bytes (not including the header). Note that this is just maxPacketLength - headerLength.

linkAddressLimit

public static final int linkAddressLimit

The upper limit on Nachos link addresses. All link addresses fall between 0 and linkAddressLimit - 1.

Constructor Detail

Packet

public Packet(int dstLink,
              int srcLink,
              byte[] contents)
       throws MalformedPacketException

Allocate a new packet to be sent, using the specified parameters.

Parameters:

dstLink - the destination link address.

srcLink - the source link address.

contents - the contents of the packet.

Packet

public Packet(byte[] packetBytes)
       throws MalformedPacketException

Allocate a new packet using the specified array of bytes received from the network.

Parameters:

packetBytes - the bytes making up this packet.