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diff --git a/src/main/java/com/jsyn/unitgen/LinearRamp.java b/src/main/java/com/jsyn/unitgen/LinearRamp.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.UnitVariablePort;
+
+/**
+ * Output approaches Input linearly.
+ * <P>
+ * When you change the value of the input port, the ramp will start changing from its current output
+ * value toward the value of input. An internal phase value will go from 0.0 to 1.0 at a rate
+ * controlled by time. When the internal phase reaches 1.0, the output will equal input.
+ * <P>
+ *
+ * @author (C) 1997 Phil Burk, SoftSynth.com
+ * @see ExponentialRamp
+ * @see AsymptoticRamp
+ * @see ContinuousRamp
+ */
+public class LinearRamp extends UnitFilter {
+    /** Time in seconds to get to the input value. */
+    public UnitInputPort time;
+    public UnitVariablePort current;
+
+    private double source;
+    private double phase;
+    private double target;
+    private double timeHeld = 0.0;
+    private double rate = 1.0;
+
+    public LinearRamp() {
+        addPort(time = new UnitInputPort("Time"));
+        addPort(current = new UnitVariablePort("Current"));
+    }
+
+    @Override
+    public void generate(int start, int limit) {
+        double[] outputs = output.getValues();
+        double currentInput = input.getValues()[0];
+        double currentValue = current.getValue();
+
+        // If input has changed, start new segment.
+        // Equality check is OK because we set them exactly equal below.
+        if (currentInput != target)
+        {
+            source = currentValue;
+            phase = 0.0;
+            target = currentInput;
+        }
+
+        if (currentValue == target) {
+            // at end of ramp
+            for (int i = start; i < limit; i++) {
+                outputs[i] = currentValue;
+            }
+        } else {
+            // in middle of ramp
+            double currentTime = time.getValues()[0];
+            // Has time changed?
+            if (currentTime != timeHeld) {
+                rate = convertTimeToRate(currentTime);
+                timeHeld = currentTime;
+            }
+
+            for (int i = start; i < limit; i++) {
+                if (phase < 1.0) {
+                    /* Interpolate current. */
+                    currentValue = source + (phase * (target - source));
+                    phase += rate;
+                } else {
+                    currentValue = target;
+                }
+                outputs[i] = currentValue;
+            }
+        }
+
+        current.setValue(currentValue);
+    }
+}