1 files changed, 72 insertions, 0 deletions
diff --git a/src/main/java/com/jsyn/unitgen/LatchZeroCrossing.java b/src/main/java/com/jsyn/unitgen/LatchZeroCrossing.java
new file mode 100644
index 0000000..9e6c011
--- /dev/null
+++ b/src/main/java/com/jsyn/unitgen/LatchZeroCrossing.java
@@ -0,0 +1,72 @@
+/*
+ * 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.unitgen;
+
+import com.jsyn.ports.UnitInputPort;
+import com.jsyn.ports.UnitOutputPort;
+
+/**
+ * Latches when input crosses zero.
+ * <P>
+ * Pass a value unchanged if gate true, otherwise pass input unchanged until input crosses zero then
+ * output zero. This can be used to turn off a sound at a zero crossing so there is no pop.
+ * <P>
+ * 
+ * @author (C) 2010 Phil Burk, Mobileer Inc
+ * @see Latch
+ * @see Minimum
+ */
+public class LatchZeroCrossing extends UnitGenerator {
+    public UnitInputPort input;
+    public UnitInputPort gate;
+    public UnitOutputPort output;
+    private double held;
+    private boolean crossed;
+
+    /* Define Unit Ports used by connect() and set(). */
+    public LatchZeroCrossing() {
+        addPort(input = new UnitInputPort("Input"));
+        addPort(gate = new UnitInputPort("Gate", 1.0));
+        addPort(output = new UnitOutputPort("Output"));
+    }
+
+    @Override
+    public void generate(int start, int limit) {
+        double[] inputs = input.getValues();
+        double[] gates = gate.getValues();
+        double[] outputs = output.getValues();
+
+        for (int i = start; i < limit; i++) {
+            double current = inputs[i];
+            if (gates[i] > 0.0) {
+                held = current;
+                crossed = false;
+            } else {
+                // If we haven't already seen a zero crossing then look for one.
+                if (!crossed) {
+                    if ((held * current) <= 0.0) {
+                        held = 0.0;
+                        crossed = true;
+                    } else {
+                        held = current;
+                    }
+                }
+            }
+            outputs[i] = held;
+        }
+    }
+}