sound.js

"use strict";

function Sound() {
	var audio;

	var play_tone = {
		"freq": 0,
		"time": 0
	};

	var rtttl = {
		"address": 0,
		"position": 0,
		"startposition": 0,
		"loop": 0,
		"play": 0,
		"default_dur": 0,
		"default_oct": 0,
		"bpm": 0,
		"wholenote": 0,
		"str": '',
		"globalSound": 1
	};

	var notes = [
		0, 262, 277, 294, 311, 330, 349, 370, 392, 415, 440, 466, 494, 523, 554, 587, 622, 659, 698, 740, 784, 831, 880,
		932, 988, 1047, 1109, 1175, 1245, 1319, 1397, 1480, 1568, 1661, 1760, 1865, 1976, 2093, 2217, 2349, 2489, 2637,
		2794, 2960, 3136, 3322, 3520, 3729, 3951
	];

	function initAudio() {
		if (!audio){
			if(!(window.AudioContext || window.webkitAudioContext)){
				audio = {};
				document.getElementById("soundCheckbox").disabled = true;
				document.getElementById("soundCheckbox").checked = false;
				rtttl.globalSound = false;
			}
			else
				audio = new(window.AudioContext || window.webkitAudioContext)();
		}
	}

	function isdigit(str) {
		return /^\d+$/.test(str);
	}

	function isNumber(value) {
		return typeof value === 'number' && isFinite(value);
	}

	function tone(freq, delay) {
		if (rtttl.globalSound) {
			var attack = 10,
			gain = audio.createGain(),
			osc = audio.createOscillator();
			gain.connect(audio.destination);
			gain.gain.value = 0.1;
			osc.frequency.value = freq;
			osc.type = "square";
			osc.connect(gain);
			osc.start(0);
			setTimeout(function () {
				osc.stop(0);
				osc.disconnect(gain);
				gain.disconnect(audio.destination);
			}, delay);
		}
	}

	function addTone(f, t) {
		play_tone.freq = f;
		play_tone.time = t;
	}

	function loadRtttl() {
		var n,
		c,
		i;
		rtttl.default_dur = 4;
		rtttl.default_oct = 6;
		rtttl.bpm = 63;
		rtttl.startposition = 0;
		i = 0;
		c = cpu.readMem(rtttl.address + i);
		rtttl.str = '';
		while (c != 0) {
			rtttl.str += String.fromCharCode(c);
			c = cpu.readMem(rtttl.address + i);
			i++;
		}
		while (c != ':' && rtttl.startposition < rtttl.str.length) {
			// ignore name
			c = rtttl.str[rtttl.startposition];
			rtttl.startposition++;
		}
		c = rtttl.str[rtttl.startposition]; // skip ':'
		// get default duration
		if (c == 'd') {
			rtttl.startposition += 2; // skip "d="
			n = '';
			while (isdigit(rtttl.str[rtttl.startposition])) {
				n += rtttl.str[rtttl.startposition];
				rtttl.startposition++;
			}
			if (parseInt(n) > 0)
				rtttl.default_dur = parseInt(n);
			rtttl.startposition++; // skip comma
		}
		// get default octave
		c = rtttl.str[rtttl.startposition];
		if (c == 'o') {
			rtttl.startposition += 2; // skip "o="
			c = rtttl.str[rtttl.startposition];
			if (parseInt(c) >= 3 && parseInt(c) <= 7)
				rtttl.default_oct = parseInt(c);
			rtttl.startposition += 2;
		}
		// get BPM
		c = rtttl.str[rtttl.startposition];
		if (c == 'b') {
			rtttl.startposition += 2; // skip "b="
			n = '';
			while (isdigit(rtttl.str[rtttl.startposition])) {
				n += rtttl.str[rtttl.startposition];
				rtttl.startposition++;
			}
			if (parseInt(n) > 0)
				rtttl.bpm = parseInt(n);
		}
		// BPM usually expresses the number of quarter notes per minute
		rtttl.wholenote = (60 * 1000 / rtttl.bpm) * 4; // this is the time for whole note (in milliseconds)
		rtttl.startposition++;
		rtttl.position = 0;
		return 1;
	}

	function testEndRtttl() {
		if (rtttl.startposition + rtttl.position >= rtttl.str.length) {
			if (!rtttl.loop)
				rtttl.play = 0;
			rtttl.position = 0;
			return true;
		}
		return false;
	}

	function playRtttl() {
		var n,
		duration,
		note,
		scale,
		c;
		//play single tone
		if (play_tone.time) {
			tone(play_tone.freq, play_tone.time);
			n = play_tone.time;
			play_tone.time = 0;
			return n;
		}
		//player
		if (rtttl.play == 0)
			return 100;
		//first, get note duration, if available
		n = 0;
		if(testEndRtttl())
			return 100;
		c = rtttl.str[rtttl.startposition + rtttl.position];
		n = '';
		while (isdigit(rtttl.str[rtttl.startposition + rtttl.position])) {
			n += rtttl.str[rtttl.startposition + rtttl.position];
			rtttl.position++;
		}
		if (isNumber(parseInt(n)) && parseInt(n) != 0)
			duration = rtttl.wholenote / n;
		else
			duration = rtttl.wholenote / rtttl.default_dur; // we will need to check if we are a dotted note after
		//now get the note
		c = rtttl.str[rtttl.startposition + rtttl.position];
		note = 0;
		switch (c) {
		case 'c':
		case 'C':
			note = 1;
			break;
		case 'd':
		case 'D':
			note = 3;
			break;
		case 'e':
		case 'E':
			note = 5;
			break;
		case 'f':
		case 'F':
			note = 6;
			break;
		case 'g':
		case 'G':
			note = 8;
			break;
		case 'a':
		case 'A':
			note = 10;
			break;
		case 'b':
		case 'B':
			note = 12;
			break;
		case 'p':
		case 'P':
		default:
			note = 0;
		}
		if (!testEndRtttl())
			rtttl.position++;
		else{
			return 100;
		}
		c = rtttl.str[rtttl.startposition + rtttl.position];
		// now, get optional '#' sharp
		if (c == '#') {
			note++;
			if (!testEndRtttl())
				rtttl.position++;
			else
				return 100;
			c = rtttl.str[rtttl.startposition + rtttl.position];
		}
		// now, get optional '.' & ';' & '&' dotted note
		if (c == '.' || c == ';' || c == '&') {
			if(c == '.')
				duration += duration / 2;
			else if(c == ';')
				duration += duration;
			else 
				duration += (duration / 2) * 3;
			if (!testEndRtttl())
				rtttl.position++;
			else
				return 100;
			c = rtttl.str[rtttl.startposition + rtttl.position];
		}
		// now, get scale
		if (isdigit(c)) {
			scale = c - '0';
			if (!testEndRtttl())
				rtttl.position++;
			else
				return 100;
			c = rtttl.str[rtttl.startposition + rtttl.position];
		} else {
			scale = rtttl.default_oct;
		}
		if (c == ',')
			rtttl.position++; // skip comma for next note (or we may be at the end)
		// now play the note
		if (note) {
			tone(notes[(scale - 4) * 12 + note], duration);
		} else {
			//console.log("Pausing: " + duration);
		}
		return duration;
	}

	return {
		initAudio: initAudio,
		rtttl: rtttl,
		tone: tone,
		addTone: addTone,
		loadRtttl: loadRtttl,
		playRtttl: playRtttl
	};
}