Initial commit.
This commit is contained in:
Ian Gulliver
309
metatron.js
Normal file
309
metatron.js
Normal file
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navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia;
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window.AudioContext = window.AudioContext || window.webkitAudioContext || window.mozAudioContext;
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var metatron = {};
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metatron.FREQS = [
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[ 1209, 1336, 1477, 1633, 2200, ],
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[ 697, 770, 852, 941 ],
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];
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metatron.POSSIBLE_VALUES = 1;
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metatron.FREQS.forEach(function(freqSet) {
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metatron.POSSIBLE_VALUES *= freqSet.length;
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});
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metatron.MARK_SECONDS = 0.2;
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metatron.FFT_SIZE = 2048;
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metatron.CYCLE_THRESHOLD = 4;
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metatron.CYCLES_PER_MARK = 8;
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metatron.checksum = function(str) {
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var checksum = 0;
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for (var i = 0; i < str.length; i++) {
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checksum ^= str.charCodeAt(i);
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}
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return checksum;
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};
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metatron.Generator = function(tag) {
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this.context_ = new AudioContext();
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this.tag_ = tag;
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};
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metatron.Generator.prototype.addPair_ = function(index, value) {
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var startOffset = metatron.MARK_SECONDS * index;
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metatron.FREQS.forEach(function(choices) {
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var freq = choices[value % choices.length];
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value = Math.floor(value / choices.length);
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var osc = this.context_.createOscillator();
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osc.frequency.value = freq;
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osc.connect(this.context_.destination);
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osc.start(this.context_.currentTime + startOffset);
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osc.stop(this.context_.currentTime + startOffset + metatron.MARK_SECONDS);
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}.bind(this));
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};
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metatron.Generator.prototype.playValue_ = function(value) {
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// Make sure we always change values.
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value += 1;
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this.lastValue_ = (this.lastValue_ + value) % metatron.POSSIBLE_VALUES;
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this.addPair_(this.indexOffset_++, this.lastValue_);
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};
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metatron.Generator.prototype.playRaw_ = function(str) {
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for (var i = 0; i < str.length; i++) {
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var chr = str.charCodeAt(i);
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// Big endian nibbles
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this.playValue_(chr >> 4);
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this.playValue_(chr % 16);
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}
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};
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metatron.Generator.prototype.play = function(str) {
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this.lastValue_ = 0;
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this.indexOffset_ = 0;
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// Resync the listener to the base value.
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this.playValue_(0);
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this.playRaw_(this.tag_);
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this.playRaw_(String.fromCharCode(str.length));
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this.playRaw_(str);
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this.playRaw_(String.fromCharCode(metatron.checksum(str)));
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};
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metatron.Listener = function(tag) {
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this.context_ = new AudioContext();
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this.activeValue_ = null;
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this.newValue_ = null;
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this.votes_ = 0;
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this.lastValue_ = 0;
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this.state_ = metatron.Listener.STATE_.WAIT_TAG;
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this.tag_ = [];
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for (var i = 0; i < tag.length; i++) {
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var chr = tag.charCodeAt(i);
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this.tag_.push(chr >> 4);
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this.tag_.push(chr % 16);
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}
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this.tagBuffer_ = [];
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navigator.getUserMedia({
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"audio": {
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"mandatory": {
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"googEchoCancellation": "false",
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"googAutoGainControl": "false",
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"googNoiseSuppression": "false",
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"googHighpassFilter": "false",
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},
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"optional": []
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}
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},
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function(stream) {
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var sampleRate = this.context_.sampleRate;
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this.analyser_ = this.context_.createAnalyser();
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this.analyser_.fftSize = metatron.FFT_SIZE;
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this.analyser_.smoothingTimeConstant = 0.0;
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this.bufSize_ = this.analyser_.frequencyBinCount;
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this.buffer_ = new Uint8Array(this.bufSize_);
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var streamSource = this.context_.createMediaStreamSource(stream);
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streamSource.connect(this.analyser_);
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var hzPerBucket = sampleRate / metatron.FFT_SIZE;
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this.fftIndices_ = [];
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metatron.FREQS.forEach(function(freqSet) {
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freqSet.forEach(function(freq) {
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this.fftIndices_.push({
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index: Math.round(freq / hzPerBucket),
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freq: freq,
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});
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}.bind(this));
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}.bind(this));
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var interval = metatron.MARK_SECONDS / metatron.CYCLES_PER_MARK * 1000;
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console.log('Poll interval:', interval, 'ms');
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window.setInterval(this.analyse_.bind(this), interval);
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}.bind(this),
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function(error) {
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}.bind(this));
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};
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metatron.Listener.STATE_ = {
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WAIT_TAG: 1,
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WAIT_LENGTH: 2,
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WAIT_CONTENTS: 3,
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WAIT_CHECKSUM: 4,
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};
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metatron.Listener.prototype.currentValue_ = function() {
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this.analyser_.getByteFrequencyData(this.buffer_);
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var values = [];
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var minValue = 255;
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this.fftIndices_.forEach(function(index) {
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minValue = Math.min(minValue, this.buffer_[index.index]);
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}.bind(this));
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this.fftIndices_.forEach(function(index) {
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values.push({
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freq: index.freq,
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value: this.buffer_[index.index] - minValue,
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});
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}.bind(this));
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values.sort(function(a, b) {
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return b.value - a.value;
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});
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var activeValues = values.slice(0, metatron.FREQS.length);
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var outputValue = 0;
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var error = false;
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activeValues.forEach(function(value) {
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var multiplier = 1, found = 0;
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metatron.FREQS.forEach(function(freqSet) {
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var index = freqSet.indexOf(value.freq);
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if (index >= 0) {
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found++;
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outputValue += index * multiplier;
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}
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multiplier *= freqSet.length;
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}.bind(this));
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if (found != 1) {
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error = true;
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console.log('Wrong number of tones matched:', found, activeValues);
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}
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}.bind(this));
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if (error) {
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return null;
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}
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return outputValue;
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};
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metatron.Listener.prototype.analyse_ = function() {
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var newValue = this.currentValue_();
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if (newValue === null) {
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return;
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}
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if (newValue === this.activeValue_) {
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this.votes_ = 0;
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this.newValue_ = null;
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return;
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}
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if (newValue === this.newValue_) {
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if (++this.votes_ == metatron.CYCLE_THRESHOLD) {
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this.onValue_(this.newValue_);
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this.activeValue_ = this.newValue_;
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this.newValue_ = null;
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this.votes_ = 0;
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}
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return;
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}
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this.newValue_ = newValue;
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this.votes_ = 1;
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};
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metatron.Listener.prototype.onValue_ = function(value) {
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var realValue = value;
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if (this.lastValue_ >= realValue) {
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realValue += metatron.POSSIBLE_VALUES;
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}
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realValue = realValue - this.lastValue_ - 1;
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this.lastValue_ = value;
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console.log(realValue);
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switch (this.state_) {
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case metatron.Listener.STATE_.WAIT_TAG:
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this.tagBuffer_.push(realValue);
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if (this.tagBuffer_.length > this.tag_.length) {
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this.tagBuffer_.shift();
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}
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if (this.tag_.equals(this.tagBuffer_)) {
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console.log('tag seen!');
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this.state_ = metatron.Listener.STATE_.WAIT_LENGTH;
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this.lengthBuffer_ = [];
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}
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break;
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case metatron.Listener.STATE_.WAIT_LENGTH:
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this.lengthBuffer_.push(realValue);
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if (this.lengthBuffer_.length == 2) {
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this.length_ = 0;
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this.lengthBuffer_.forEach(function(part) {
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this.length_ <<= 4;
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this.length_ += part;
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}.bind(this));
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this.contentsParts_ = [];
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this.state_ = metatron.Listener.STATE_.WAIT_CONTENTS;
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}
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break;
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case metatron.Listener.STATE_.WAIT_CONTENTS:
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this.contentsParts_.push(realValue);
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if (this.contentsParts_.length == this.length_ * 2) {
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var chrs = [];
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for (i = 0; i < this.contentsParts_.length; i += 2) {
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chrs.push(String.fromCharCode((this.contentsParts_[i] << 4)
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+ this.contentsParts_[i + 1]));
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}
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this.contents_ = chrs.join('');
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this.checksumParts_ = [];
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this.state_ = metatron.Listener.STATE_.WAIT_CHECKSUM;
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}
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break;
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case metatron.Listener.STATE_.WAIT_CHECKSUM:
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this.checksumParts_.push(realValue);
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if (this.checksumParts_.length == 2) {
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var checksum = 0;
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this.checksumParts_.forEach(function(part) {
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checksum <<= 4;
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checksum += part;
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}.bind(this));
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if (checksum == metatron.checksum(this.contents_)) {
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console.log('checksum match');
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document.getElementById('value').textContent = this.contents_;
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} else {
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console.log('corrupted message');
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}
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this.state_ = metatron.Listener.STATE_.WAIT_TAG;
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}
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break;
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}
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};
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Array.prototype.equals = function(other) {
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if (this.length != other.length) {
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return false;
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}
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for (var i = 0; i < this.length; i++) {
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if (this[i] != other[i]) {
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return false;
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}
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}
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return true;
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};
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