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diff --git a/libjava/gnu/java/awt/BitMaskExtent.java b/libjava/gnu/java/awt/BitMaskExtent.java
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+++ b/libjava/gnu/java/awt/BitMaskExtent.java
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+/* Copyright (C) 2000, 2002  Free Software Foundation
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+02111-1307 USA.
+
+As a special exception, if you link this library with other files to
+produce an executable, this library does not by itself cause the
+resulting executable to be covered by the GNU General Public License.
+This exception does not however invalidate any other reasons why the
+executable file might be covered by the GNU General Public License. */
+
+package gnu.java.awt;
+
+/** 
+ * Simple transparent utility class that can be used to perform bit
+ * mask extent calculations.
+ */
+public final class BitMaskExtent
+{
+  /** The number of the least significant bit of the bit mask extent. */
+  public byte leastSignificantBit;
+
+  /** The number of bits in the bit mask extent. */
+  public byte bitWidth;
+  
+  /**
+   * Set the bit mask. This will calculate and set the leastSignificantBit
+   * and bitWidth fields.
+   *
+   * @see #leastSignificantBit
+   * @see #bitWidth
+   */
+  public void setMask(long mask)
+  {
+    leastSignificantBit = 0;
+    bitWidth = 0;
+    if (mask == 0) return;
+    long shiftMask = mask;
+    for (; (shiftMask&1) == 0; shiftMask >>>=1) leastSignificantBit++;
+    for (; (shiftMask&1) != 0; shiftMask >>>=1) bitWidth++;
+    
+    if (shiftMask != 0)
+      throw new IllegalArgumentException("mask must be continuous");
+  }
+  
+  /** 
+   * Calculate the bit mask based on the values of the
+   * leastSignificantBit and bitWidth fields.
+   */
+  public long toMask()
+  {
+    return ((1<<bitWidth)-1) << leastSignificantBit;
+  }  
+}