1 //******************************************************************************
2 //
3 // File: SharedSigned8BitIntegerBuf.java
4 // Package: edu.rit.mp.buf
5 // Unit: Class edu.rit.mp.buf.SharedSigned8BitIntegerBuf
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.mp.Signed8BitIntegerBuf;
46 import edu.rit.pj.reduction.IntegerOp;
47 import edu.rit.pj.reduction.Op;
48 import edu.rit.pj.reduction.SharedInteger;
49
50 /**
51 * Class SharedSigned8BitIntegerBuf provides a buffer for a shared signed 8-bit
52 * integer item sent or received using the Message Protocol (MP). While an
53 * instance of class SharedSigned8BitIntegerBuf may be constructed directly,
54 * normally you will use a factory method in class {@linkplain
55 * edu.rit.mp.Signed8BitIntegerBuf Signed8BitIntegerBuf}. See that class for
56 * further information.
57 *
58 * @author Alan Kaminsky
59 * @version 26-Oct-2007
60 */
61 public class SharedSigned8BitIntegerBuf
62 extends Signed8BitIntegerBuf {
63
64 // Hidden data members.
65 SharedInteger myItem;
66
67 // Exported constructors.
68 /**
69 * Construct a new shared signed 8-bit integer buffer.
70 *
71 * @param item SharedInteger object that wraps the item.
72 */
73 public SharedSigned8BitIntegerBuf(SharedInteger item) {
74 super(1);
75 myItem = item;
76 }
77
78 // Exported operations.
79 /**
80 * {@inheritDoc}
81 *
82 * Obtain the given item from this buffer.
83 * <P>
84 * The <code>get()</code> method must not block the calling thread; if it does,
85 * all message I/O in MP will be blocked.
86 */
87 public int get(int i) {
88 return myItem.get();
89 }
90
91 /**
92 * {@inheritDoc}
93 *
94 * Store the given item in this buffer.
95 * <P>
96 * The <code>put()</code> method must not block the calling thread; if it does,
97 * all message I/O in MP will be blocked.
98 */
99 public void put(int i,
100 int item) {
101 myItem.set(item);
102 }
103
104 /**
105 * {@inheritDoc}
106 *
107 * Create a buffer for performing parallel reduction using the given binary
108 * operation. The results of the reduction are placed into this buffer.
109 * @exception ClassCastException (unchecked exception) Thrown if this
110 * buffer's element data type and the given binary operation's argument data
111 * type are not the same.
112 */
113 public Buf getReductionBuf(Op op) {
114 return new SharedSigned8BitIntegerReductionBuf(myItem, (IntegerOp) op);
115 }
116
117 // Hidden operations.
118 /**
119 * {@inheritDoc}
120 *
121 * Send as many items as possible from this buffer to the given byte buffer.
122 * <P>
123 * The <code>sendItems()</code> method must not block the calling thread; if it
124 * does, all message I/O in MP will be blocked.
125 */
126 protected int sendItems(int i,
127 ByteBuffer buffer) {
128 if (buffer.remaining() >= 1) {
129 buffer.put((byte) myItem.get());
130 return 1;
131 } else {
132 return 0;
133 }
134 }
135
136 /**
137 * {@inheritDoc}
138 *
139 * Receive as many items as possible from the given byte buffer to this
140 * buffer.
141 * <P>
142 * The <code>receiveItems()</code> method must not block the calling thread; if
143 * it does, all message I/O in MP will be blocked.
144 */
145 protected int receiveItems(int i,
146 int num,
147 ByteBuffer buffer) {
148 if (num >= 1 && buffer.remaining() >= 1) {
149 myItem.set(buffer.get());
150 return 1;
151 } else {
152 return 0;
153 }
154 }
155
156 }