/*
JPC: An x86 PC Hardware Emulator for a pure Java Virtual Machine
Release Version 2.4
A project from the Physics Dept, The University of Oxford
Copyright (C) 2007-2010 The University of Oxford
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:
jpc.sourceforge.net
or the developer website
sourceforge.net/projects/jpc/
Conceived and Developed by:
Rhys Newman, Ian Preston, Chris Dennis
End of licence header
*/
package org.jpc.emulator.motherboard;
import org.jpc.emulator.AbstractHardwareComponent;
/**
* This class holds the map between ioport addresses and <code>IODevice</code>
* objects. Unmapped ports are redirected to an unconnected inner class instance
* whose data lines float high, and on which writes fail silently.
* @author Chris Dennis
*/
public class IOPortHandler extends AbstractHardwareComponent implements IODevice
{
private static final int MAX_IOPORTS = 65536;
private static final IODevice defaultDevice = new UnconnectedIOPort();
private IODevice[] ioPortDevice;
/**
* Constructs a new <code>IOPortHandler</code> with an initially empty ioport
* mapping. All ioports map to the unconnected instance.
*/
public IOPortHandler()
{
ioPortDevice = new IODevice[MAX_IOPORTS];
for (int i = 0; i < ioPortDevice.length; i++)
ioPortDevice[i] = defaultDevice;
}
public int ioPortRead8(int address)
{
return ioPortDevice[address].ioPortRead8(address);
}
public int ioPortRead16(int address)
{
return ioPortDevice[address].ioPortRead16(address);
}
public int ioPortRead32(int address)
{
return ioPortDevice[address].ioPortRead32(address);
}
public void ioPortWrite8(int address, int data)
{
ioPortDevice[address].ioPortWrite8(address, data);
}
public void ioPortWrite16(int address, int data)
{
ioPortDevice[address].ioPortWrite16(address, data);
}
public void ioPortWrite32(int address, int data)
{
ioPortDevice[address].ioPortWrite32(address, data);
}
public int[] ioPortsRequested()
{
return null;
}
/**
* Map an <code>IODevice</code> device into this handler.
* <p>
* The range of ioports requested by this device are registered with the
* handler. Each individual port is registered only if that port is
* currently unconnected.
* @param device object to be mapped.
*/
public void registerIOPortCapable(IODevice device)
{
int[] portArray = device.ioPortsRequested();
if (portArray == null) return;
for (int port : portArray) {
if (ioPortDevice[port] == defaultDevice)
ioPortDevice[port] = device;
}
}
/**
* Unmap an <code>IODevice</code> device from this handler.
* <p>
* Ports are only unmapped from the handler if they are currently to the
* supplied object. References to other objects at the addresses claimed
* are not cleared.
* @param device object to be unmapped.
*/
public void deregisterIOPortCapable(IODevice device)
{
int[] portArray = device.ioPortsRequested();
for (int port : portArray) {
if (ioPortDevice[port] == device)
ioPortDevice[port] = defaultDevice;
}
}
public void reset()
{
ioPortDevice = new IODevice[MAX_IOPORTS];
for (int i = 0; i < ioPortDevice.length; i++)
ioPortDevice[i] = defaultDevice;
}
public String toString()
{
return "IOPort Bus";
}
private static class UnconnectedIOPort implements IODevice
{
public int ioPortRead8(int address)
{
return 0xff;
}
public int ioPortRead16(int address)
{
return 0xffff;
}
public int ioPortRead32(int address)
{
return 0xffffffff;
}
public void ioPortWrite8(int address, int data)
{
}
public void ioPortWrite16(int address, int data)
{
}
public void ioPortWrite32(int address, int data)
{
}
public int[] ioPortsRequested()
{
return null;
}
}
}