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1   //******************************************************************************
2   //
3   // File:    BooleanItemReductionBuf.java
4   // Package: edu.rit.mp.buf
5   // Unit:    Class edu.rit.mp.buf.BooleanItemReductionBuf
6   //
7   // This Java source file is copyright (C) 2007 by Alan Kaminsky. All rights
8   // reserved. For further information, contact the author, Alan Kaminsky, at
9   // ark@cs.rit.edu.
10  //
11  // This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
12  // software; you can redistribute it and/or modify it under the terms of the GNU
13  // General Public License as published by the Free Software Foundation; either
14  // version 3 of the License, or (at your option) any later version.
15  //
16  // PJ is distributed in the hope that it will be useful, but WITHOUT ANY
17  // WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
18  // A PARTICULAR PURPOSE. See the GNU General Public License for more details.
19  //
20  // Linking this library statically or dynamically with other modules is making a
21  // combined work based on this library. Thus, the terms and conditions of the GNU
22  // General Public License cover the whole combination.
23  //
24  // As a special exception, the copyright holders of this library give you
25  // permission to link this library with independent modules to produce an
26  // executable, regardless of the license terms of these independent modules, and
27  // to copy and distribute the resulting executable under terms of your choice,
28  // provided that you also meet, for each linked independent module, the terms
29  // and conditions of the license of that module. An independent module is a module
30  // which is not derived from or based on this library. If you modify this library,
31  // you may extend this exception to your version of the library, but you are not
32  // obligated to do so. If you do not wish to do so, delete this exception
33  // statement from your version.
34  //
35  // A copy of the GNU General Public License is provided in the file gpl.txt. You
36  // may also obtain a copy of the GNU General Public License on the World Wide
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38  //
39  //******************************************************************************
40  package edu.rit.mp.buf;
41  
42  import java.nio.ByteBuffer;
43  
44  import edu.rit.mp.BooleanBuf;
45  import edu.rit.mp.Buf;
46  import edu.rit.pj.reduction.BooleanOp;
47  import edu.rit.pj.reduction.Op;
48  
49  /**
50   * Class BooleanItemReductionBuf provides a reduction buffer for class
51   * {@linkplain BooleanItemBuf}.
52   *
53   * @author Alan Kaminsky
54   * @version 25-Oct-2007
55   */
56  class BooleanItemReductionBuf
57          extends BooleanBuf {
58  
59  // Hidden data members.
60      BooleanItemBuf myBuf;
61      BooleanOp myOp;
62  
63  // Exported constructors.
64      /**
65       * Construct a new Boolean item reduction buffer.
66       *
67       * @param buf Buffer containing the item.
68       * @param op Binary operation.
69       * @exception NullPointerException (unchecked exception) Thrown if
70       * <code>op</code> is null.
71       */
72      public BooleanItemReductionBuf(BooleanItemBuf buf,
73              BooleanOp op) {
74          super(1);
75          if (op == null) {
76              throw new NullPointerException("BooleanItemReductionBuf(): op is null");
77          }
78          myBuf = buf;
79          myOp = op;
80      }
81  
82  // Exported operations.
83      /**
84       * {@inheritDoc}
85       *
86       * Obtain the given item from this buffer.
87       * <P>
88       * The <code>get()</code> method must not block the calling thread; if it does,
89       * all message I/O in MP will be blocked.
90       */
91      public boolean get(int i) {
92          return myBuf.item;
93      }
94  
95      /**
96       * {@inheritDoc}
97       *
98       * Store the given item in this buffer. The item at index <code>i</code> in this
99       * buffer is combined with the given <code>item</code> using the binary
100      * operation.
101      * <P>
102      * The <code>put()</code> method must not block the calling thread; if it does,
103      * all message I/O in MP will be blocked.
104      */
105     public void put(int i,
106             boolean item) {
107         myBuf.item = myOp.op(myBuf.item, item);
108     }
109 
110     /**
111      * {@inheritDoc}
112      *
113      * Create a buffer for performing parallel reduction using the given binary
114      * operation. The results of the reduction are placed into this buffer.
115      * @exception ClassCastException (unchecked exception) Thrown if this
116      * buffer's element data type and the given binary operation's argument data
117      * type are not the same.
118      */
119     public Buf getReductionBuf(Op op) {
120         throw new UnsupportedOperationException();
121     }
122 
123 // Hidden operations.
124     /**
125      * {@inheritDoc}
126      *
127      * Send as many items as possible from this buffer to the given byte buffer.
128      * <P>
129      * The <code>sendItems()</code> method must not block the calling thread; if it
130      * does, all message I/O in MP will be blocked.
131      */
132     protected int sendItems(int i,
133             ByteBuffer buffer) {
134         if (buffer.remaining() >= 1) {
135             buffer.put(myBuf.item ? (byte) 1 : (byte) 0);
136             return 1;
137         } else {
138             return 0;
139         }
140     }
141 
142     /**
143      * {@inheritDoc}
144      *
145      * Receive as many items as possible from the given byte buffer to this
146      * buffer. As the items are received, they are combined with the items in
147      * this buffer using the binary operation.
148      * <P>
149      * The <code>receiveItems()</code> method must not block the calling thread; if
150      * it does, all message I/O in MP will be blocked.
151      */
152     protected int receiveItems(int i,
153             int num,
154             ByteBuffer buffer) {
155         if (num >= 1 && buffer.remaining() >= 1) {
156             myBuf.item = myOp.op(myBuf.item, buffer.get() != 0);
157             return 1;
158         } else {
159             return 0;
160         }
161     }
162 
163 }