// Copyright (c) -2016 The Regents of the University of California.
// All rights reserved.
//
// Permission is hereby granted, without written agreement and without
// license or royalty fees, to use, copy, modify, and distribute this
// software and its documentation for any purpose, provided that the above
// copyright notice and the following two paragraphs appear in all copies
// of this software.
//
// IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
// ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
// THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
// PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
// CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
// ENHANCEMENTS, OR MODIFICATIONS.
//
/** This accessor returns an array of FFT coefficients, corresponding to the input signal.
*
* @accessor services/FFT
* @author Ilge Akkaya
* @version $$Id$$
* @input {array<number>} signalIn Input signal array
* @output {array<{'real':'number', 'imag': 'number'}>} fftOutput An array of FFT coefficients, each being a record with real and imaginary parts.
*/
// Stop extra messages from jslint and jshint. Note that there should
// be no space between the / and the * and global. See
// https://chess.eecs.berkeley.edu/ptexternal/wiki/Main/JSHint */
/*globals addInputHandler, exports, get, input, output, removeInputHandler, require, send */
/*jshint globalstrict: true*/
'use strict';
exports.setup = function () {
this.input('signalIn');
this.output('fftOutput');
};
var dspEngine = null;
var dsp = require("dsp");
var handle = null;
var processSignal = function () {
var signalValue = this.get('signalIn');
var fftLength = signalValue.length;
var fftResult = dspEngine.fft(signalValue);
var outputArray = [];
// parse the fft coefficients as record tokens with
// real and imaginary parts
for (var j = 0; j < fftLength; j += 1) {
var trial = {};
trial.real = fftResult.real[j];
trial.imag = fftResult.imag[j];
outputArray[j] = trial;
}
this.send('fftOutput', outputArray);
};
exports.initialize = function () {
handle = this.addInputHandler('signalIn', processSignal);
var n = 0;
dspEngine = new dsp.Signal();
};
exports.wrapup = function () {
this.removeInputHandler('signalIn', handle);
};