/*
    Copyright (c) 1996-1997 Swiss Federal Institute of Technology, 
    Computer Engineering and Networks Laboratory. All rights reserved.

    Written by George Fankhauser <gfa@acm.org>. For more documentation
    please visit http://www.tik.ee.ethz.ch/~gfa.
    


    
    File:                  $Source: /usr/drwho/vault/cvs/topsy/MipsSim/PSXConsole.java,v $
    Author(s):             George Fankhauser
    Affiliation:           ETH Zuerich, TIK
    Version:               $Revision: 1.1 $
    Creation Date:         December 1999
    Last Date of Change:   $Date: 2000/05/08 18:47:51 $      by: $Author: gfa $
    
    
    $Log: PSXConsole.java,v $
    Revision 1.1  2000/05/08 18:47:51  gfa
    new playstation stuff...


*/

import java.io.*;
import java.util.*;
import MemoryRegion;


public class PSXConsole extends MemoryRegion {
	
	final int PSXADDRSIZE = 20;
	final int STATUS_REGISTER = 0x04;
	final int COMMAND_REGISTER = 0x08;
	final int TX_REGISTER = 0x0c;
	final int RX_REGISTER = TX_REGISTER;
	final int MODE_REGISTER = 0x10;
	
	final byte RECV_MASK = 0x01;
	final byte READY_TO_SEND = 0x04;
	 
	InputStream in = System.in;
	int subcycles = 0;
	
	public PSXConsole(int baseAddress) {
		from = baseAddress; 
		to = baseAddress+PSXADDRSIZE;
		memory = new byte[to-from+1];
	}
	
	// read
	byte readByte(int address) throws BusErrorException {
		int offset = address-from;
		
		if (offset == STATUS_REGISTER) {
		    // simulator is always ready to send...
		    return (byte)(memory[STATUS_REGISTER] | READY_TO_SEND); 
		}
		else if (offset == RX_REGISTER) {
		    memory[STATUS_REGISTER] &= ~RECV_MASK; // clear status
		    return memory[RX_REGISTER];
		}
		else if (offset == MODE_REGISTER) {
		    return memory[MODE_REGISTER];
		}
		return 0;
	}
	
	void writeByte(int address, byte data) throws BusErrorException {	
	    int offset = address-from;
	    
	    super.writeByte(address, data);
	    if (offset == TX_REGISTER) {
		System.out.write(data);
		System.out.flush();
	    }
	    else if (offset == MODE_REGISTER) {
	    }
	}
	
	// input on the psx?!
	void checkInterrupt(Processor p) throws IOException {

		try {
			if (in.available() > 0) {
			    memory[RX_REGISTER] = (byte)(in.read());
			    memory[STATUS_REGISTER] |= RECV_MASK; // set
			    //p.interrupt(xxx);
			}
		}
		catch (IOException e) {
			System.out.print(e.getClass().getName()+
						" ("+
e.getMessage()+")\n");
			System.out.println("PSXCon: couldn't read stdin");
		}
	}
}