Utility class for tracking trailing averages.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@2502 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/media/util/TrailingAverage.java

@@ -0,0 +1,63 @@
+//
+// $Id: TrailingAverage.java,v 1.1 2003/04/30 00:38:35 mdb Exp $
+
+package com.threerings.media.util;
+
+/**
+ * Used to compute a trailing average of a value.
+ */
+public class TrailingAverage
+{
+    /**
+     * Creates a trailing average instance with the default number of
+     * values used to compute the average (10).
+     */
+    public TrailingAverage ()
+    {
+        this(10);
+    }
+
+    /**
+     * Creates a trailing average instance with the specified number of
+     * values used to compute the average.
+     */
+    public TrailingAverage (int history)
+    {
+        _history = new int[history];
+    }
+
+    /**
+     * Records a new value.
+     */
+    public void record (int value)
+    {
+        _history[_index++%_history.length] = value;
+    }
+
+    /**
+     * Returns the current averaged value.
+     */
+    public int value ()
+    {
+        int end = Math.min(_history.length, _index);
+        int value = 0;
+        for (int ii = 0; ii < end; ii++) {
+            value += _history[ii];
+        }
+        return (end > 0) ? (value/end) : 0;
+    }
+
+    /**
+     * Returns the current trailing average value as a string.
+     */
+    public String toString ()
+    {
+        return Integer.toString(value());
+    }
+
+    /** The history of values. */
+    protected int[] _history;
+
+    /** The index where we will next record a value. */
+    protected int _index;
+}