src/main/java/com/loomcom/symon/devices/Via6522.java

/*
 * Copyright (c) 2016 Seth J. Morabito <web@loomcom.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package com.loomcom.symon.devices;

import com.loomcom.symon.exceptions.MemoryAccessException;
import com.loomcom.symon.exceptions.MemoryRangeException;

/**
 * Very basic implementation of a MOS 6522 VIA.
 *
 * TODO: Implement timers as threads.
 */
public class Via6522 extends Pia {
	public static final int VIA_SIZE = 16;

	enum Register {
		ORB, ORA, DDRB, DDRA, T1C_L, T1C_H, T1L_L, T1L_H, T2C_L, T2C_H, SR, ACR, PCR, IFR, IER, ORA_H
	}

	public Via6522(int address) throws MemoryRangeException {
		super(address, address + VIA_SIZE - 1, "MOS 6522 VIA");
	}

	@Override
	public void write(int address, int data) throws MemoryAccessException {
		Register[] registers = Register.values();

		if (address >= registers.length) {
			throw new MemoryAccessException("Unknown register: " + address);
		}

		Register r = registers[address];

		switch (r) {
		case ORA:
		case ORB:
		case DDRA:
		case DDRB:
		case T1C_L:
		case T1C_H:
		case T1L_L:
		case T1L_H:
		case T2C_L:
		case T2C_H:
		case SR:
		case ACR:
		case PCR:
		case IFR:
		case IER:
		case ORA_H:
		default:
		}
	}

	@Override
	public int read(int address) throws MemoryAccessException {
		Register[] registers = Register.values();

		if (address >= registers.length) {
			throw new MemoryAccessException("Unknown register: " + address);
		}

		Register r = registers[address];

		switch (r) {
		case ORA:
		case ORB:
		case DDRA:
		case DDRB:
		case T1C_L:
		case T1C_H:
		case T1L_L:
		case T1L_H:
		case T2C_L:
		case T2C_H:
		case SR:
		case ACR:
		case PCR:
		case IFR:
		case IER:
		case ORA_H:
		default:
		}

		return 0;
	}
}