1 //******************************************************************************
2 //
3 // File: SharedUnsigned16BitIntegerReductionBuf.java
4 // Package: edu.rit.mp.buf
5 // Unit: Class edu.rit.mp.buf.SharedUnsigned16BitIntegerReductionBuf
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
37 // Web at http://www.gnu.org/licenses/gpl.html.
38 //
39 //******************************************************************************
40 package edu.rit.mp.buf;
41
42 import java.nio.ByteBuffer;
43
44 import edu.rit.mp.Buf;
45 import edu.rit.pj.reduction.IntegerOp;
46 import edu.rit.pj.reduction.Op;
47 import edu.rit.pj.reduction.SharedInteger;
48
49 /**
50 * Class SharedUnsigned16BitIntegerReductionBuf provides a reduction buffer for
51 * class {@linkplain SharedUnsigned16BitIntegerBuf}.
52 *
53 * @author Alan Kaminsky
54 * @version 26-Oct-2007
55 */
56 class SharedUnsigned16BitIntegerReductionBuf
57 extends SharedUnsigned16BitIntegerBuf {
58
59 // Hidden data members.
60 IntegerOp myOp;
61
62 // Exported constructors.
63 /**
64 * Construct a new shared unsigned 16-bit integer reduction buffer.
65 *
66 * @param item SharedInteger object that wraps the item.
67 * @param op Binary operation.
68 * @exception NullPointerException (unchecked exception) Thrown if
69 * <code>op</code> is null.
70 */
71 public SharedUnsigned16BitIntegerReductionBuf(SharedInteger item,
72 IntegerOp op) {
73 super(item);
74 if (op == null) {
75 throw new NullPointerException("SharedUnsigned16BitIntegerReductionBuf(): op is null");
76 }
77 myOp = op;
78 }
79
80 // Exported operations.
81 /**
82 * {@inheritDoc}
83 *
84 * Store the given item in this buffer.
85 * <P>
86 * The <code>put()</code> method must not block the calling thread; if it does,
87 * all message I/O in MP will be blocked.
88 */
89 public void put(int i,
90 int item) {
91 myItem.reduce(item, myOp);
92 }
93
94 /**
95 * {@inheritDoc}
96 *
97 * Create a buffer for performing parallel reduction using the given binary
98 * operation. The results of the reduction are placed into this buffer.
99 * @exception ClassCastException (unchecked exception) Thrown if this
100 * buffer's element data type and the given binary operation's argument data
101 * type are not the same.
102 */
103 public Buf getReductionBuf(Op op) {
104 throw new UnsupportedOperationException();
105 }
106
107 // Hidden operations.
108 /**
109 * {@inheritDoc}
110 *
111 * Receive as many items as possible from the given byte buffer to this
112 * buffer.
113 * <P>
114 * The <code>receiveItems()</code> method must not block the calling thread; if
115 * it does, all message I/O in MP will be blocked.
116 */
117 protected int receiveItems(int i,
118 int num,
119 ByteBuffer buffer) {
120 if (num >= 1 && buffer.remaining() >= 2) {
121 myItem.reduce(buffer.getShort() & 0xFFFF, myOp);
122 return 1;
123 } else {
124 return 0;
125 }
126 }
127
128 }