diff -N HPSEcalDiscriminatorReadoutDriver.java
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ HPSEcalDiscriminatorReadoutDriver.java	2 Sep 2011 23:37:17 -0000	1.1
@@ -0,0 +1,100 @@

+package org.lcsim.hps.recon.ecal;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.lcsim.event.CalorimeterHit;
+import org.lcsim.geometry.IDDecoder;
+import org.lcsim.hps.util.ClockSingleton;
+import org.lcsim.hps.util.RingBuffer;
+
+/**
+ * Performs readout of ECal hits.
+ * Simulates time evolution of preamp output pulse.
+ * 
+ * @author Sho Uemura <[log in to unmask]>
+ * @version $Id: HPSEcalDiscriminatorReadoutDriver.java,v 1.1 2011/09/02 23:37:17 meeg Exp $
+ */
+public class HPSEcalDiscriminatorReadoutDriver extends HPSEcalReadoutDriver {
+
+    //buffer for deposited energy
+    Map<Long, RingBuffer> eDepMap = null;
+    //last time we saw a rising edge
+    Map<Long, Double> edgeTimeMap = null;
+    //length of ring buffer (in multiples of bunch spacing)
+    int bufferLength = 200;
+    //shaper time constant in ns
+    double t0 = 18.0;
+    //discriminator output pulse width in ns
+    double outputWidth = 32.0;
+    //output hit "energy" in GeV
+    double outputEnergy = 10.0;
+
+    public HPSEcalDiscriminatorReadoutDriver() {
+    }
+
+    public void setBufferLength(int bufferLength) {
+        this.bufferLength = bufferLength;
+        eDepMap = new HashMap<Long, RingBuffer>();
+    }
+
+    public List<HPSRawCalorimeterHit> readHits() {
+        IDDecoder dec = ecal.getIDDecoder();
+        List<HPSRawCalorimeterHit> hitList = new ArrayList<HPSRawCalorimeterHit>();
+        for (Long cellID : edgeTimeMap.keySet()) {
+            //if there's an output pulse, make a hit
+            if (ClockSingleton.getTime() - edgeTimeMap.get(cellID) < outputWidth) {
+                dec.setID(cellID);
+                hitList.add(new HPSRawCalorimeterHit(outputEnergy, dec.getPosition(), 0.0, cellID, hitType));
+            }
+        }
+        return hitList;
+    }
+
+    public void putHits(List<CalorimeterHit> hits) {
+        //fill the readout buffers
+        for (CalorimeterHit hit : hits) {
+            IDDecoder dec = ecal.getIDDecoder();
+            dec.setID(hit.getCellID());
+//            int ix = dec.getValue("ix");
+//            int iy = dec.getValue("iy");
+//            //temporary hack to disable crystals and flip X coordinate
+//            int side = dec.getValue("side");
+//            if (iy == 1 && ix * side >= -10 && ix * side <= -2)
+//                continue;
+
+            RingBuffer eDepBuffer = eDepMap.get(hit.getCellID());
+            if (eDepBuffer == null) {
+                eDepBuffer = new RingBuffer(bufferLength);
+                eDepMap.put(hit.getCellID(), eDepBuffer);
+            }
+            for (int i = 0; i < bufferLength; i++) {
+                eDepBuffer.addToCell(i, hit.getRawEnergy() * pulseAmplitude(i * ClockSingleton.getDt() - hit.getTime()));
+            }
+        }
+
+        //check for rising edges
+        for (Long cellID : eDepMap.keySet()) {
+            RingBuffer eDepBuffer = eDepMap.get(cellID);
+            //if there's a rising edge between now and the next time step, note the time
+            if ((eDepBuffer.currentValue() < threshold)
+                    && (eDepBuffer.getValue(1) > threshold))
+                edgeTimeMap.put(cellID, ClockSingleton.getTime());
+            eDepBuffer.step();
+        }
+    }
+
+    public void initReadout() {
+        //initialize buffers
+        eDepMap = new HashMap<Long, RingBuffer>();
+        edgeTimeMap = new HashMap<Long, Double>();
+    }
+
+    private double pulseAmplitude(double time) {
+        if (time < 0.0)
+            return 0.0;
+        return (time / t0) * Math.exp(1.0 - time / t0);
+    }
+}

\ No newline at end of file

diff -u -r1.11 -r1.12
--- HPSEcalReadoutDriver.java	30 Aug 2011 22:00:33 -0000	1.11
+++ HPSEcalReadoutDriver.java	2 Sep 2011 23:37:17 -0000	1.12
@@ -15,7 +15,7 @@

  * Performs readout of ECal hits.
  * 
  * @author Sho Uemura <[log in to unmask]>

- * @version $Id: HPSEcalReadoutDriver.java,v 1.11 2011/08/30 22:00:33 meeg Exp $

+ * @version $Id: HPSEcalReadoutDriver.java,v 1.12 2011/09/02 23:37:17 meeg Exp $

  */
 public abstract class HPSEcalReadoutDriver extends Driver {
 

@@ -99,6 +99,7 @@

     public abstract List<HPSRawCalorimeterHit> readHits();
 
     //add deposited energy to buffers

+    //must be run every event, even if the list is empty

     public abstract void putHits(List<CalorimeterHit> hits);
 
     //initialize buffers

diff -u -r1.2 -r1.3
--- RingBuffer.java	24 Aug 2011 21:30:14 -0000	1.2
+++ RingBuffer.java	2 Sep 2011 23:37:17 -0000	1.3
@@ -4,7 +4,7 @@

  * Ring buffer for storing ECal (and possibly SVT) samples for trigger and readout
  *
  * @author Sho Uemura <[log in to unmask]>

- * @version $Id: RingBuffer.java,v 1.2 2011/08/24 21:30:14 meeg Exp $

+ * @version $Id: RingBuffer.java,v 1.3 2011/09/02 23:37:17 meeg Exp $

  */
 public class RingBuffer {
 

@@ -25,6 +25,11 @@

     public double currentValue() {
         return array[ptr];
     }

+    
+    //return content of specified cell (pos=0 for current cell)
+    public double getValue(int pos) {
+        return array[(ptr+pos)%size];
+    }

      
     /**
      * Clear value at current cell and step to the next one