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function MorseNode(ac, rate) { | |
// ac is an audio context. | |
this._oscillator = ac.createOscillator(); | |
this._gain = ac.createGain(); | |
this._gain.gain.value = 0; | |
this._oscillator.frequency.value = 750; | |
this._oscillator.connect(this._gain); | |
if(rate == undefined) | |
rate = 20; | |
this._dot = 1.2 / rate; // formula from Wikipedia. | |
this._oscillator.start(0); | |
} | |
MorseNode.prototype.connect = function(target) { | |
return this._gain.connect(target); | |
} | |
MorseNode.prototype.MORSE = { | |
"A": ".-", | |
"B": "-...", | |
"C": "-.-.", | |
"D": "-..", | |
"E": ".", | |
"F": "..-.", | |
"G": "--.", | |
"H": "....", | |
"I": "..", | |
"J": ".---", | |
"K": "-.-", | |
"L": ".-..", | |
"M": "--", | |
"N": "-.", | |
"O": "---", | |
"P": ".--.", | |
"Q": "--.-", | |
"R": ".-.", | |
"S": "...", | |
"T": "-", | |
"U": "..-", | |
"W": ".--", | |
"X": "-..-", | |
"Y": "-.--", | |
"Z": "--..", | |
"1": ".----", | |
"2": "..---", | |
"3": "...--", | |
"4": "....-", | |
"5": ".....", | |
"6": "-....", | |
"7": "--...", | |
"8": "---..", | |
"9": "----.", | |
"0": "-----" | |
}; | |
MorseNode.prototype.playChar = function(t, c) { | |
for(var i = 0; i < c.length; i++) { | |
switch(c[i]) { | |
case '.': | |
this._gain.gain.setValueAtTime(1.0, t); | |
t += this._dot; | |
this._gain.gain.setValueAtTime(0.0, t); | |
break; | |
case '-': | |
this._gain.gain.setValueAtTime(1.0, t); | |
t += 3 * this._dot; | |
this._gain.gain.setValueAtTime(0.0, t); | |
break; | |
} | |
t += this._dot; | |
} | |
return t; | |
} | |
MorseNode.prototype.playString = function(t, w) { | |
w = w.toUpperCase(); | |
for(var i = 0; i < w.length; i++) { | |
if(w[i] == ' ') { | |
t += 3 * this._dot; // 3 dots from before, three here, and | |
// 1 from the ending letter before. | |
} | |
else if(this.MORSE[w[i]] != undefined) { | |
t = this.playChar(t, this.MORSE[w[i]]); | |
t += 2 * this._dot; | |
} | |
} | |
return t; | |
} |
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