Add the whispernet proxy.

chrome/browser/resources/whispernet_proxy/js/wrapper.js

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+

[xiyuan, 2014/07/31 19:22:23]

nit: 'use strict';

[rkc, 2014/07/31 23:12:53]

Done.

+/**
+ * Function to convert an array of bytes to a base64 string
+ * @param {string} bytes String containing the bytes we want to convert.

[xiyuan, 2014/07/31 19:22:23]

nit: Think |bytes| should be an Uint8Array (or we create a Uint8Array out of
it).

[rkc, 2014/07/31 23:12:53]

This is the form this comes to us from Nacl. It is less than ideal, but I'll
look into making this better.

[xiyuan, 2014/08/01 19:24:27]

Let's put a TODO for this. Ideally, nacl should send us an ArrayBuffer and we
could map that to a Uint8Array view here.

[rkc, 2014/08/01 21:21:12]

Done.

+ * @return {string} String containing the base64 representation.
+ */
+function bytesToBase64(bytes) {
+  var bstr = '';
+  for (var i = 0; i < bytes.length; ++i)
+    bstr += String.fromCharCode(bytes[i]);
+  return btoa(bstr);
+}
+
+/**
+ * Function to convert a string to an array of bytes.
+ * @param {string} str String to convert.
+ * @return {Array} Array containing the string.
+ */
+function stringToArray(str) {
+  var buffer = [];
+  for (var i = 0; i < str.length; ++i)
+    buffer[i] = str.charCodeAt(i);
+  return buffer;
+}
+
+/**
+ * Creates a whispernet encoder.
+ * @constructor
+ * @param {Object} params Dictionary of parameters used to initialize the
+ * whispernet encoder.
+ * @param {Object} whisperNacl The NaclBridge object to use to communicate with
+ * the whispernet wrapper.
+ */
+function WhisperEncoder(params, whisperNacl) {
+  params = params || {};
+  this.repetitions_ = params.repetitions || 3;
+
+  this.whisperNacl_ = whisperNacl;
+  this.whisperNacl_.addListener(this.onNaclMessage_.bind(this));
+
+  var symbolCoder = {};
+  symbolCoder.sample_rate = params.sampleRate || 48000.0;
+  symbolCoder.upsampling_factor = params.bitsPerSample || 16;
+  symbolCoder.desired_carrier_frequency = params.carrierFrequency || 18500.0;
+  symbolCoder.bits_per_symbol = 4;
+  symbolCoder.min_cycles_per_frame = 4;
+  symbolCoder.baseband_decimation_factor = 4;
+
+  var msg = {
+    type: 'initialize_encoder',
+    symbol_coder: symbolCoder,
+    encoder_params: {
+      bytes_per_token: 6,
+      include_parity_symbol: true,
+      single_sideband: true
+    }
+  };
+  this.whisperNacl_.send(JSON.stringify(msg));
+}
+
+/**
+ * Method to encode a token.
+ * @param {string} token Token to encode.
+ * @param {boolean} raw Whether we should return the encoded samples in raw
+ * format or as a Wave file.
+ */
+WhisperEncoder.prototype.encode = function(token, raw) {
+  var msg = {
+    type: 'encode_token',
+    // Trying to send the token in binary form to Nacl doesn't work correctly.
+    // We end up with the correct string + a bunch of extra characters. This is
+    // true of returning a binary string too; hence we communicate back and
+    // forth by converting the bytes into an array of integers.
+    token: stringToArray(token),
+    repetitions: this.repetitions_,
+    return_raw_samples: raw
+  };
+  this.whisperNacl_.send(JSON.stringify(msg));
+};
+
+/**
+ * Method to set the callback for encoded audio data received from the encoder
+ * when we finish encoding a token.
+ * @param {function(string, ArrayBuffer)} callback Callback which will receive
+ * the audio samples.
+ */
+WhisperEncoder.prototype.onAudioData = function(callback) {

[xiyuan, 2014/07/31 19:22:23]

nit: onAudioData -> setAudioDataCallback or some name more intuitive.

[rkc, 2014/07/31 23:12:53]

Done.

+  this.audioDataCallback_ = callback;
+};
+
+/**
+ * Method to handle messages from the whispernet NaCl wrapper.
+ * @param {Event} e Event from the whispernet wrapper.
+ * @private
+ */
+WhisperEncoder.prototype.onNaclMessage_ = function(e) {
+  var msg = e.data;
+  if (msg.type == 'encode_token_response') {
+    this.audioDataCallback_(bytesToBase64(msg.token), msg.samples);
+  }
+};
+
+/**
+ * Creates a whispernet decoder.
+ * @constructor
+ * @param {Object} params Dictionary of parameters used to initialize the
+ * whispernet decoder.
+ * @param {Object} whisperNacl The NaclBridge object to use to communicate with
+ * the whispernet wrapper.
+ */
+function WhisperDecoder(params, whisperNacl) {
+  params = params || {};
+
+  this.whisperNacl_ = whisperNacl;
+  this.whisperNacl_.addListener(this.onNaclMessage_.bind(this));
+
+  var msg = {
+    type: 'initialize_decoder',
+    num_channels: params.channels,
+    symbol_coder: {
+      sample_rate: params.sampleRate || 48000.0,
+      upsampling_factor: params.bitsPerSample || 16,
+      desired_carrier_frequency: params.carrierFrequency || 18500.0,
+      bits_per_symbol: 4,
+      min_cycles_per_frame: 4,
+      baseband_decimation_factor: 4
+    },
+    decoder_params: {
+      bytes_per_token: 6,
+      include_parity_symbol: true,
+      max_candidates: 1,
+      broadcaster_stopped_threshold_in_seconds: 10
+    },
+    acquisition_params: {
+      max_buffer_duration_in_seconds: 3
+    }
+  };
+  this.whisperNacl_.send(JSON.stringify(msg));
+}
+
+/**
+ * Method to request the decoder to wipe its internal buffer.
+ */
+WhisperDecoder.prototype.wipeDecoder = function() {
+  var msg = {
+    type: 'wipe_decode_buffer'
+  };
+  this.whisperNacl_.send(JSON.stringify(msg));
+};
+
+/**
+ * Method to request the decoder to detect a broadcast.
+ */
+WhisperDecoder.prototype.detectBroadcast = function() {
+  var msg = {
+    type: 'detect_broadcast'
+  };
+  this.whisperNacl_.send(JSON.stringify(msg));
+};
+
+/**
+ * Method to request the decoder to process samples.
+ * @param {ArrayBuffer} samples Array of samples to process.
+ */
+WhisperDecoder.prototype.processSamples = function(samples) {
+  // For sample processing, the Nacl module doesn't expect any frills in the
+  // message, just send the samples directly.
+  this.whisperNacl_.send(samples);
+};
+
+/**
+ * Method to set the callback for decoded tokens received from the decoder.
+ * @param {function(!Array.string)} callback Callback to receive the list of
+ * decoded tokens.
+ */
+WhisperDecoder.prototype.onReceive = function(callback) {

[xiyuan, 2014/07/31 19:22:23]

similar here. onReceive -> setReceiveCallback.

[rkc, 2014/07/31 23:12:53]

Done.

+  this.tokenCallback_ = callback;
+};
+
+/**
+ * Method to set the callback for receiving the detect callback status received
+ * from the decoder.
+ * @param {function()} callback Callback to set to receive the detect broadcast
+ * status.
+ */
+WhisperDecoder.prototype.onDetectBroadcast = function(callback) {
+  this.detectBroadcastCallback_ = callback;
+};
+
+/**
+ * Method to handle messages from the whispernet NaCl wrapper.
+ * @param {Event} e Event from the whispernet wrapper.
+ * @private
+ */
+WhisperDecoder.prototype.onNaclMessage_ = function(e) {
+  var msg = e.data;
+  if (msg.type == 'decode_tokens_response') {
+    this.handleCandidates_(JSON.parse(msg.tokens));
+  } else if (msg.type == 'detect_broadcast_response') {
+    this.detectBroadcastCallback_(msg.detected);
+  }
+};
+
+/**
+ * Method to receive tokens from the decoder and process and forward them to the
+ * token callback registered with us.
+ * @param {!Array.string} candidates Array of token candidates.
+ * @private
+ */
+WhisperDecoder.prototype.handleCandidates_ = function(candidates) {
+  if (!this.tokenCallback_ || !candidates || candidates.length == 0)
+    return;
+
+  var returnCandidates = [];
+  for (var i = 0; i < candidates.length; ++i)
+    returnCandidates[i] = bytesToBase64(candidates[i]);
+  this.tokenCallback_(returnCandidates);
+};