From 580fea450ec0982d0bd8be589f00566267e7b0d1 Mon Sep 17 00:00:00 2001
From: Phil Burk <philburk@mobileer.com>
Date: Tue, 2 Aug 2016 07:52:17 -0700
Subject: Instruments: add better synth, pitch control

---
 src/com/jsyn/unitgen/PowerOfTwo.java | 79 ++++++++++++++++++++----------------
 1 file changed, 44 insertions(+), 35 deletions(-)

(limited to 'src/com/jsyn/unitgen/PowerOfTwo.java')

diff --git a/src/com/jsyn/unitgen/PowerOfTwo.java b/src/com/jsyn/unitgen/PowerOfTwo.java
index 5f1b4cd..5916860 100644
--- a/src/com/jsyn/unitgen/PowerOfTwo.java
+++ b/src/com/jsyn/unitgen/PowerOfTwo.java
@@ -4,9 +4,9 @@
  * 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.
@@ -22,18 +22,23 @@ import com.jsyn.ports.UnitOutputPort;
 /**
  * output = (2.0^input) This is useful for converting a pitch modulation value into a frequency
  * scaler. An input value of +1.0 will output 2.0 for an octave increase. An input value of -1.0
- * will output 0.5 for an octave decrease. This implementation uses a table lookup to optimize for
+ * will output 0.5 for an octave decrease.
+ *
+ * This implementation uses a table lookup to optimize for
  * speed. It is accurate enough for tuning. It also checks to see if the current input value is the
  * same as the previous input value. If so then it reuses the previous computed value.
- * 
+ *
  * @author Phil Burk (C) 2010 Mobileer Inc
  */
 public class PowerOfTwo extends UnitGenerator {
+    /**
+     * Offset in octaves.
+     */
     public UnitInputPort input;
     public UnitOutputPort output;
 
     private static double[] table;
-    private static final int NUM_VALUES = 1024;
+    private static final int NUM_VALUES = 2048;
     // Cached computation.
     private double lastInput = 0.0;
     private double lastOutput = 1.0;
@@ -61,39 +66,43 @@ public class PowerOfTwo extends UnitGenerator {
         double[] inputs = input.getValues();
         double[] outputs = output.getValues();
 
-        if (true) {
-            for (int i = start; i < limit; i++) {
-                double in = inputs[i];
-                // Can we reuse a previously computed value?
-                if (in == lastInput) {
-                    outputs[i] = lastOutput;
-                } else {
-                    int octave = (int) Math.floor(in);
-                    double normal = in - octave;
-                    // Do table lookup.
-                    double findex = normal * NUM_VALUES;
-                    int index = (int) findex;
-                    double fraction = findex - index;
-                    double value = table[index] + (fraction * (table[index + 1] - table[index]));
+        for (int i = start; i < limit; i++) {
+            double in = inputs[i];
+            // Can we reuse a previously computed value?
+            if (in == lastInput) {
+                outputs[i] = lastOutput;
+            } else {
+                lastInput = in;
+                double adjustedInput = adjustInput(in);
+                int octave = (int) Math.floor(adjustedInput);
+                double normal = adjustedInput - octave;
+                // Do table lookup.
+                double findex = normal * NUM_VALUES;
+                int index = (int) findex;
+                double fraction = findex - index;
+                double value = table[index] + (fraction * (table[index + 1] - table[index]));
 
-                    // Adjust for octave.
-                    while (octave > 0) {
-                        octave -= 1;
-                        value *= 2.0;
-                    }
-                    while (octave < 0) {
-                        octave += 1;
-                        value *= 0.5;
-                    }
-                    outputs[i] = value;
-                    lastInput = in;
-                    lastOutput = value;
+                // Adjust for octave.
+                while (octave > 0) {
+                    octave -= 1;
+                    value *= 2.0;
                 }
-            }
-        } else {
-            for (int i = start; i < limit; i++) {
-                outputs[i] = Math.pow(2.0, inputs[i]);
+                while (octave < 0) {
+                    octave += 1;
+                    value *= 0.5;
+                }
+                double adjustedOutput = adjustOutput(value);
+                outputs[i] = adjustedOutput;
+                lastOutput = adjustedOutput;
             }
         }
     }
+
+    public double adjustInput(double in) {
+        return in;
+    }
+
+    public double adjustOutput(double out) {
+        return out;
+    }
 }
-- 
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