1 files changed, 109 insertions, 0 deletions
diff --git a/src/main/java/com/jsyn/data/DoubleTable.java b/src/main/java/com/jsyn/data/DoubleTable.java
new file mode 100644
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+++ b/src/main/java/com/jsyn/data/DoubleTable.java
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+/*
+ * Copyright 2010 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.data;
+
+import com.jsyn.exceptions.ChannelMismatchException;
+
+/**
+ * Evaluate a Function by interpolating between the values in a table. This can be used for
+ * wavetable lookup or waveshaping.
+ *
+ * @author Phil Burk (C) 2010 Mobileer Inc
+ */
+public class DoubleTable implements Function {
+    private double[] table;
+
+    public DoubleTable(int numFrames) {
+        allocate(numFrames);
+    }
+
+    public DoubleTable(double[] data) {
+        allocate(data.length);
+        write(data);
+    }
+
+    public DoubleTable(ShortSample shortSample) {
+        if (shortSample.getChannelsPerFrame() != 1) {
+            throw new ChannelMismatchException("DoubleTable can only be built from mono samples.");
+        }
+        short[] buffer = new short[256];
+        int framesLeft = shortSample.getNumFrames();
+        allocate(framesLeft);
+        int cursor = 0;
+        while (framesLeft > 0) {
+            int numTransfer = framesLeft;
+            if (numTransfer > buffer.length) {
+                numTransfer = buffer.length;
+            }
+            shortSample.read(cursor, buffer, 0, numTransfer);
+            write(cursor, buffer, 0, numTransfer);
+            cursor += numTransfer;
+            framesLeft -= numTransfer;
+        }
+    }
+
+    public void allocate(int numFrames) {
+        table = new double[numFrames];
+    }
+
+    public int length() {
+        return table.length;
+    }
+
+    public void write(double[] data) {
+        write(0, data, 0, data.length);
+    }
+
+    public void write(int startFrame, short[] data, int startIndex, int numFrames) {
+        for (int i = 0; i < numFrames; i++) {
+            table[startFrame + i] = data[startIndex + i] * (1.0 / 32768.0);
+        }
+    }
+
+    public void write(int startFrame, double[] data, int startIndex, int numFrames) {
+        for (int i = 0; i < numFrames; i++) {
+            table[startFrame + i] = data[startIndex + i];
+        }
+    }
+
+    /**
+     * Treat the double array as a lookup table with a domain of -1.0 to 1.0. If the input is out of
+     * range then the output will clip to the end values.
+     *
+     * @param input
+     * @return interpolated value from table
+     */
+    @Override
+    public double evaluate(double input) {
+        double interp;
+        if (input < -1.0) {
+            interp = table[0];
+        } else if (input < 1.0) {
+            double fractionalIndex = (table.length - 1) * (input - (-1.0)) / 2.0;
+            // We don't need floor() because fractionalIndex >= 0.0
+            int index = (int) fractionalIndex;
+            double fraction = fractionalIndex - index;
+
+            double s1 = table[index];
+            double s2 = table[index + 1];
+            interp = ((s2 - s1) * fraction) + s1;
+        } else {
+            interp = table[table.length - 1];
+        }
+        return interp;
+    }
+}