timer.java

JPC: x86 PC Hardware Emulator. 牛津大学开发的一个纯JAVA的x86系统结构硬件模拟器。

/*
    JPC: A x86 PC Hardware Emulator for a pure Java Virtual Machine
    Release Version 2.0

    A project from the Physics Dept, The University of Oxford

    Copyright (C) 2007 Isis Innovation Limited

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License version 2 as published by
    the Free Software Foundation.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
    Details (including contact information) can be found at: 

    www.physics.ox.ac.uk/jpc
*/

package org.jpc.emulator;

import org.jpc.support.*;
import java.io.*;

public class Timer implements ComparableObject
{
    private long expireTime;
    private HardwareComponent callback;
    private boolean enabled;

    private Clock myOwner;

    public Timer(HardwareComponent object, Clock parent)
    {
	myOwner = parent;
	callback = object;
	enabled = false;
    }

    public void dumpState(DataOutput output) throws IOException
    {
        output.writeLong(expireTime);
        output.writeBoolean(enabled);
    }

    public void loadState(DataInput input) throws IOException
    {
        setExpiry(input.readLong());
        setStatus(input.readBoolean());
    }

    public boolean enabled()
    {
	return enabled;
    }

    public void setStatus(boolean status)
    {
	enabled = status;
	myOwner.update(this);
    }

    public void setExpiry(long time)
    {
	expireTime = time;
	this.setStatus(true);
    }

    public boolean check(long time)
    {
	return this.enabled && (time >= expireTime);
    }

    public void runCallback()
    {
	callback.timerCallback();
    }

    public long getExpiry()
    {
	return expireTime;
    }

    public int compareTo(Object o)
    {
        if (!(o instanceof Timer))
            return -1;

	if (this.enabled()) 
        {
	    if (!((Timer)o).enabled())
		return -1;
	    else if (((Timer) this).getExpiry() - ((Timer) o).getExpiry() < 0)
		return -1;
	    else if (((Timer) this).getExpiry() - ((Timer) o).getExpiry() > 0)
		return 1;
	    else
		return 0;
	} 
        else 
	    return 1; //stick disabled timers at end of list
    }


}