1 files changed, 61 insertions, 0 deletions
diff --git a/src/main/java/com/jsyn/unitgen/ZeroCrossingCounter.java b/src/main/java/com/jsyn/unitgen/ZeroCrossingCounter.java
new file mode 100644
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+++ b/src/main/java/com/jsyn/unitgen/ZeroCrossingCounter.java
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+/*
+ * Copyright 1997 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;
+
+/**
+ * Count zero crossings. Handy for unit tests.
+ * 
+ * @author (C) 1997-2011 Phil Burk, Mobileer Inc
+ */
+public class ZeroCrossingCounter extends UnitGenerator {
+    private static final double THRESHOLD = 0.0001;
+    public UnitInputPort input;
+    public UnitOutputPort output;
+
+    private long count;
+    private boolean armed;
+
+    /* Define Unit Ports used by connect() and set(). */
+    public ZeroCrossingCounter() {
+        addPort(input = new UnitInputPort("Input"));
+        addPort(output = new UnitOutputPort("Output"));
+    }
+
+    @Override
+    public void generate(int start, int limit) {
+        double[] inputs = input.getValues();
+        double[] outputs = output.getValues();
+
+        for (int i = start; i < limit; i++) {
+            double value = inputs[i];
+            if (value < -THRESHOLD) {
+                armed = true;
+            } else if (armed & (value > THRESHOLD)) {
+                ++count;
+                armed = false;
+            }
+            outputs[i] = value;
+        }
+    }
+
+    public long getCount() {
+        return count;
+    }
+}