/*
 * 	6502 Based Virtual Computer
 *	Copyright (C) 2011  Scott C. Duensing <scott@jaegertech.com>
 *	
 *	This program is free software; you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License as published by
 *	the Free Software Foundation; either version 2 of the License, or
 *	(at your option) any later version.
 *	
 *	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.
 */

// Our Clock object.
function clock() {

	// --- Private variables.

	// Memory location for clock value.
	var MEMORY            = null;
	var MEMORY_START      = 0;
	var CLOCK_ADDRESS     = 0;

	// Clock values.
	var MILLISECONDS  = 0;
	var CLOCK         = 0;
	var CLOCK_RUNNING = true;

	
	// --- Private methods.
	
	var clockTick = function() {
		if (CLOCK_RUNNING) {
			MEMORY.writeByte(CLOCK_ADDRESS, CLOCK++);
			if (CLOCK > 255) CLOCK = 0;
		}
		setTimeout(function(){
			clockTick();
		}, MILLISECONDS);
	};
	
	
	// --- Public methods.

	// Attach clock to DOM.
	this.attach = function(newMemory, newStartPosition, newMilliseconds) {
		MEMORY       = newMemory;
		MEMORY_START = newStartPosition;
		CLOCK_ADDRESS = MEMORY_START;
		MILLISECONDS  = newMilliseconds;
		clockTick();
	};

	// Deserialize clock state.
	this.deserialize = function(state) {
		CLOCK = state.C;
		CLOCK_RUNNING = state.R;
	};
	
	// Pause the clock.
	this.pause = function() {
		console.log("Pausing Clock.");
		CLOCK_RUNNING = false;
	};

	// Start the clock.
	this.run = function() {
		console.log("Starting Clock.");
		CLOCK_RUNNING = true;
	};
	
	// Serialize clock state.
	this.serialize = function() {
		var state = {
			C: CLOCK,
			R: CLOCK_RUNNING
		};
		return state;
	};
}