packet.java

Java Op Processor java vhdl processor

/*
 * Copyright (c) Martin Schoeberl, [e-mail]
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Martin Schoeberl
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

/*
*   Changelog:
*		2002-11-11	use LinkLayer info to mix Slip and Ethernet packets
*/

package ejip;

import util.Dbg;

/**
*	Packet buffer handling for a minimalistic TCP/IP stack.
*
*/
public class Packet {

	public final static int MAX = 1500;		// maximum Packet length in bytes
	public final static int MAXW = 1500/4;	// maximum Packet length in word
	public final static int MAXLLH = 7;		// 7 16 bit words for ethernet
	private final static int CNT = 8;		// size of packet pool

	/** interface source/destination */
	public LinkLayer interf;
	/** place for link layer data */
	public int[] llh;
	/** ip datagram */
	public int[] buf;
	/** length in bytes */
	public int len;
	/** usage of packet */
	private int status;
	public final static int FREE = 0;
	public final static int ALLOC = 1;
	public final static int SND = 2;
	public final static int RCV = 3;

	private static Object monitor;

	//	no direct construction
	private Packet() {
		llh = new int[MAXLLH];
		buf = new int[MAXW];
		len = 0;
		status = FREE;
		interf = null;
	}

	private static boolean initOk;
	private static Packet[] packets;

	// a small race condition on init
	public static void init() {

		if (initOk) return;
		monitor = new Object();

		synchronized (monitor) {
			initOk = true;
			packets = new Packet[CNT];
			for (int i=0; i<CNT; ++i) {
				packets[i] = new Packet();
			}
		}
	}

private static void dbg() {

	synchronized (monitor) {
		Dbg.wr('|');
		for (int i=0; i<CNT; ++i) {
			Dbg.wr('0'+packets[i].status);
		}
		Dbg.wr('|');
	}
}


/**
*	Request a packet of a given type from the pool and set new type.
*/
	public static Packet getPacket(int type, int newType) {

		int i;
		Packet p;

		if (!initOk) {
			init();
		}
		synchronized (monitor) {
			for (i=0; i<CNT; ++i) {
				if (packets[i].status==type) {
					break;
				}
			}
			if (i==CNT) {
if (type==FREE) Dbg.wr('!');
				return null;
			}
			packets[i].status = newType;
			p = packets[i];
		}
// dbg();
		return p;
	}

/**
*	Request a packet of a given type from the pool and set new type and source.
*/
	public static Packet getPacket(int type, int newType, LinkLayer s) {

		int i;
		Packet p;

		if (!initOk) {
			init();
		}
		synchronized (monitor) {
			for (i=0; i<CNT; ++i) {
				if (packets[i].status==type) {
					break;
				}
			}
			if (i==CNT) {
if (type==FREE) Dbg.wr('!');
				return null;
			}
			packets[i].status = newType;
			packets[i].interf = s;
			p = packets[i];
		}
// dbg();
		return p;
	}

/**
*	Request a packet of a given type and source from the pool and set new type.
*/
	public static Packet getPacket(LinkLayer s, int type, int newType) {

		int i;
		Packet p;

		if (!initOk) {
			init();
		}
		synchronized (monitor) {
			for (i=0; i<CNT; ++i) {
				if (packets[i].status==type && packets[i].interf==s) {
					break;
				}
			}
			if (i==CNT) {
				return null;
			}
			packets[i].status = newType;
			p = packets[i];
		}
// dbg();
		return p;
	}

	public void setStatus(int v) {

		synchronized (monitor) {
			status = v;
		}
// dbg();
	}

	public int getStatus() {
		return status;
	}

	public LinkLayer getLinkLayer() {
		return interf;
	}
}