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diff --git a/src/main/java/com/jsyn/unitgen/PinkNoise.java b/src/main/java/com/jsyn/unitgen/PinkNoise.java
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+/*
+ * Copyright 2009 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.ports.UnitInputPort;
+import com.jsyn.ports.UnitOutputPort;
+import com.jsyn.util.PseudoRandom;
+
+/**
+ * Random output with 3dB per octave rolloff providing a soft natural noise sound. Generated using
+ * Gardner method. Optimization suggested by James McCartney uses a tree to select which random
+ * value to replace.
+ * 
+ * <pre>
+ *  x x x x x x x x x x x x x x x x 
+ *  x   x   x   x   x   x   x   x   
+ *  x       x       x       x       
+ *  x               x               
+ *  x
+ * </pre>
+ * 
+ * Tree is generated by counting trailing zeros in an increasing index. When the index is zero, no
+ * random number is selected. Author: Phil Burk (C) 1996 SoftSynth.com.
+ */
+
+public class PinkNoise extends UnitGenerator implements UnitSource {
+
+    public UnitInputPort amplitude;
+    public UnitOutputPort output;
+
+    private final int NUM_ROWS = 16;
+    private final int RANDOM_BITS = 24;
+    private final int RANDOM_SHIFT = 32 - RANDOM_BITS;
+
+    private PseudoRandom randomNum;
+    protected double prevNoise, currNoise;
+
+    private long[] rows = new long[NUM_ROWS]; // NEXT RANDOM UNSIGNED 32
+    private double scalar; // used to scale within range of -1.0 to +1.0
+    private int runningSum; // used to optimize summing of generators
+    private int index; // incremented with each sample
+    private int indexMask; // index wrapped and ANDing with this mask
+
+    /* Define Unit Ports used by connect() and set(). */
+    public PinkNoise() {
+        addPort(amplitude = new UnitInputPort("Amplitude", UnitOscillator.DEFAULT_AMPLITUDE));
+        addPort(output = new UnitOutputPort("Output"));
+
+        randomNum = new PseudoRandom();
+
+        // set up for N rows of generators
+        index = 0;
+        indexMask = (1 << NUM_ROWS) - 1;
+
+        // Calculate maximum possible signed random value. Extra 1 for white
+        // noise always added.
+        int pmax = (NUM_ROWS + 1) * (1 << (RANDOM_BITS - 1));
+        scalar = 1.0 / pmax;
+
+        // initialize rows
+        for (int i = 0; i < NUM_ROWS; i++) {
+            rows[i] = 0;
+        }
+
+        runningSum = 0;
+    }
+
+    @Override
+    public void generate(int start, int limit) {
+        double[] amplitudes = amplitude.getValues();
+        double[] outputs = output.getValues();
+
+        for (int i = start; i < limit; i++) {
+            outputs[i] = generatePinkNoise() * amplitudes[i];
+        }
+    }
+
+    public double generatePinkNoise() {
+        index = (index + 1) & indexMask;
+
+        // If index is zero, don't update any random values.
+        if (index != 0) {
+            // Determine how many trailing zeros in PinkIndex.
+            // This algorithm will hang of n==0 so test first
+            int numZeros = 0;
+            int n = index;
+
+            while ((n & 1) == 0) {
+                n = n >> 1;
+                numZeros++;
+            }
+
+            // Replace the indexed ROWS random value.
+            // Subtract and add back to RunningSum instead of adding all the
+            // random values together. Only one changes each time.
+            runningSum -= rows[numZeros];
+            int newRandom = randomNum.nextRandomInteger() >> RANDOM_SHIFT;
+            runningSum += newRandom;
+            rows[numZeros] = newRandom;
+        }
+
+        // Add extra white noise value.
+        int newRandom = randomNum.nextRandomInteger() >> RANDOM_SHIFT;
+        int sum = runningSum + newRandom;
+
+        // Scale to range of -1.0 to 0.9999.
+        return scalar * sum;
+    }
+
+    @Override
+    public UnitOutputPort getOutput() {
+        return output;
+    }
+}