Dave Hoover
02899d1083
git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@6407 542714f4-19e9-0310-aa3c-eee0fc999fb1
92 lines
2.4 KiB
Java
92 lines
2.4 KiB
Java
//
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// $Id$
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//
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// Narya library - tools for developing networked games
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// Copyright (C) 2002-2011 Three Rings Design, Inc., All Rights Reserved
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// http://code.google.com/p/narya/
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//
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// This library is free software; you can redistribute it and/or modify it
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// under the terms of the GNU Lesser General Public License as published
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// by the Free Software Foundation; either version 2.1 of the License, or
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// (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package com.threerings.io;
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import java.io.IOException;
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/**
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* Used to keep track of which entries in an array are null and which are
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* not. <em>Note:</em> only arrays up to 262,144 elements in length can be
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* handled by this class.
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*/
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public class ArrayMask
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{
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/**
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* Creates an array mask suitable for unserializing.
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*/
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public ArrayMask ()
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{
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}
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/**
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* Creates an array mask for an array of the specified length.
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*/
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public ArrayMask (int length)
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{
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int mlength = length/8;
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if (length % 8 != 0) {
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mlength++;
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}
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_mask = new byte[mlength];
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}
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/**
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* Sets the bit indicating that the specified array index is non-null.
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*/
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public void set (int index)
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{
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_mask[index/8] |= (1 << (index%8));
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}
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/**
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* Returns true if the specified array index should be non-null.
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*/
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public boolean isSet (int index)
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{
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return (_mask[index/8] & (1 << (index%8))) != 0;
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}
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/**
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* Writes this mask to the specified output stream.
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*/
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public void writeTo (ObjectOutputStream out)
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throws IOException
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{
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out.writeShort(_mask.length);
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out.write(_mask);
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}
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/**
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* Reads this mask from the specified input stream.
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*/
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public void readFrom (ObjectInputStream in)
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throws IOException
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{
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int length = in.readShort();
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_mask = new byte[length];
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in.read(_mask);
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}
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/** A byte array with bits for every entry in the source array. */
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protected byte[] _mask;
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}
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