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diff --git a/src/com/jsyn/unitgen/FFTBase.java b/src/com/jsyn/unitgen/FFTBase.java
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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();
+}