ioresourceimpl.java

来自「纯java操作系统jnode,安装简单和操作简单的个人使用的Java操作系统」· Java 代码 · 共 148 行

/*
 * $Id: IOResourceImpl.java,v 1.1 2003/11/25 11:41:17 epr Exp $
 */
package org.jnode.vm;

import org.jnode.system.IOResource;
import org.jnode.system.ResourceNotFreeException;
import org.jnode.system.ResourceOwner;
import org.jnode.util.NumberUtils;


/**
 * Default implementation of IOResource.
 * 
 * @author Ewout Prangsma ([e-mail])
 */
final class IOResourceImpl extends Region implements IOResource {

	/** The first port of this resource */
	private int startPort;
	/** The length of the port region */
	private int length;
	/** Has this resource been released? */
	private boolean released;
	/** The list of active IOResource's */
	private static Region resources;

	/**
	 * Create a new instance
	 * @param owner
	 * @param startPort
	 * @param length
	 */
	private IOResourceImpl(ResourceOwner owner, int startPort, int length) {
		super(owner);
		this.startPort = startPort;
		this.length = length;
		this.released = false;
	}

	/**
	 * Claim a range of IO ports
	 * @param owner
	 * @param startPort
	 * @param length
	 * @return The claimed resource
	 * @throws ResourceNotFreeException
	 */
	protected static synchronized IOResource claimIOResource(ResourceOwner owner, int startPort, int length) 
	throws ResourceNotFreeException {
		final IOResourceImpl res = new IOResourceImpl(owner, startPort, length);
		if (isFree(resources, res)) {
			resources = add(resources, res);
			return res;
		} else {
			final Object curOwner = get(resources, res).getOwner();
			throw new ResourceNotFreeException("port " + NumberUtils.hex(startPort) + "-" + NumberUtils.hex(startPort+length-1) + " is owned by " + curOwner);
		}
	}

	/**
	 * Returns the length.
	 * @return int
	 */
	public int getLength() {
		return length;
	}

	/**
	 * Returns the startPort.
	 * @return int
	 */
	public int getStartPort() {
		return startPort;
	}

	public int inPortByte(int portNr) {
		testPort(portNr, 1);
		return Unsafe.inPortByte(portNr);
	}

	public int inPortWord(int portNr) {
		testPort(portNr, 2);
		return Unsafe.inPortWord(portNr);
	}

	public int inPortDword(int portNr) {
		testPort(portNr, 4);
		return Unsafe.inPortDword(portNr);
	}

	public void outPortByte(int portNr, int value) {
		testPort(portNr, 1);
		Unsafe.outPortByte(portNr, value);
	}

	public void outPortWord(int portNr, int value) {
		testPort(portNr, 2);
		Unsafe.outPortWord(portNr, value);
	}

	public void outPortDword(int portNr, int value) {
		testPort(portNr, 4);
		Unsafe.outPortDword(portNr, value);
	}

	/**
	 * Compare to regions.
	 * @param otherRegion
	 * @return a negative integer, zero, or a positive integer as 
	 *   this object is less than, equal to, or greater than the 
	 *   specified region. If the regions overlap, 0 is returned.
	 */
	public int compareTo(Region otherRegion) {
		final IOResourceImpl other = (IOResourceImpl)otherRegion;
		if (this.startPort + this.length <= other.startPort) {
			return -1;
		} else if (this.startPort >= other.startPort + other.length) {
			return 1;
		} else {
			return 0;
		}

	}

	/**
	 * Give up this resource. After this method has been called, the resource
	 * cannot be used anymore.
	 */
	public void release() {
		if (!this.released) {
			this.released = true;
			synchronized (getClass()) {
				resources = remove(resources, this);
			}
		}
	}

	private void testPort(int portNr, int size) {
		if (released) {
			throw new IndexOutOfBoundsException("Resource is released");
		}
		if ((portNr < startPort) || ((portNr + size) > (startPort + length))) {
			throw new IndexOutOfBoundsException();
		}
	}
}