| /* 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., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| 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; |
| } |
| } |