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/*
* Copyright 2013 Phil Burk, Mobileer Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.jsyn.unitgen;
import com.jsyn.data.Spectrum;
import com.jsyn.ports.UnitInputPort;
import com.jsyn.ports.UnitOutputPort;
import com.softsynth.math.FourierMath;
/**
* Periodically transform the complex input signal using an FFT to a complex spectral stream.
*
* @author Phil Burk (C) 2013 Mobileer Inc
* @version 016
* @see IFFT
*/
public abstract class FFTBase extends UnitGenerator {
public UnitInputPort inputReal;
public UnitInputPort inputImaginary;
public UnitOutputPort outputReal;
public UnitOutputPort outputImaginary;
protected double[] realInput;
protected double[] realOutput;
protected double[] imaginaryInput;
protected double[] imaginaryOutput;
protected int cursor;
protected FFTBase() {
addPort(inputReal = new UnitInputPort("InputReal"));
addPort(inputImaginary = new UnitInputPort("InputImaginary"));
addPort(outputReal = new UnitOutputPort("OutputReal"));
addPort(outputImaginary = new UnitOutputPort("OutputImaginary"));
setSize(Spectrum.DEFAULT_SIZE);
}
public void setSize(int size) {
realInput = new double[size];
realOutput = new double[size];
imaginaryInput = new double[size];
imaginaryOutput = new double[size];
cursor = 0;
}
public int getSize() {
return realInput.length;
}
@Override
public void generate(int start, int limit) {
double[] inputRs = inputReal.getValues();
double[] inputIs = inputImaginary.getValues();
double[] outputRs = outputReal.getValues();
double[] outputIs = outputImaginary.getValues();
for (int i = start; i < limit; i++) {
realInput[cursor] = inputRs[i];
imaginaryInput[cursor] = inputIs[i];
outputRs[i] = realOutput[cursor];
outputIs[i] = imaginaryOutput[cursor];
cursor += 1;
// When it is full, do the FFT.
if (cursor == realInput.length) {
// Copy to output buffer so we can do the FFT in place.
System.arraycopy(realInput, 0, realOutput, 0, realInput.length);
System.arraycopy(imaginaryInput, 0, imaginaryOutput, 0, imaginaryInput.length);
FourierMath.transform(getSign(), realOutput.length, realOutput, imaginaryOutput);
cursor = 0;
}
}
}
protected abstract int getSign();
}
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