1 //******************************************************************************
2 //
3 // File: EmptySigned16BitIntegerBuf.java
4 // Package: edu.rit.mp.buf
5 // Unit: Class edu.rit.mp.buf.EmptySigned16BitIntegerBuf
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.Signed16BitIntegerBuf;
46 import edu.rit.pj.reduction.IntegerOp;
47 import edu.rit.pj.reduction.Op;
48
49 /**
50 * Class EmptySigned16BitIntegerBuf provides a signed 16-bit integer buffer that
51 * contains no items for messages using the Message Protocol (MP). When a
52 * message is sent from an EmptySigned16BitIntegerBuf, the message item type is
53 * signed 16-bit <code>int</code> and the message length is 0. When a message is
54 * received into an EmptySigned16BitIntegerBuf, the message item type must be
55 * signed 16-bit <code>int</code>, but all items in the message are discarded.
56 *
57 * @author Alan Kaminsky
58 * @version 19-Nov-2007
59 */
60 public class EmptySigned16BitIntegerBuf
61 extends Signed16BitIntegerBuf {
62
63 // Exported constructors.
64 /**
65 * Construct a new empty signed 16-bit integer buffer.
66 */
67 public EmptySigned16BitIntegerBuf() {
68 super(0);
69 }
70
71 // Exported operations.
72 /**
73 * {@inheritDoc}
74 *
75 * Obtain the given item from this buffer.
76 * <P>
77 * The <code>get()</code> method must not block the calling thread; if it does,
78 * all message I/O in MP will be blocked.
79 */
80 public int get(int i) {
81 throw new IndexOutOfBoundsException();
82 }
83
84 /**
85 * {@inheritDoc}
86 *
87 * Store the given item in this buffer.
88 * <P>
89 * The <code>put()</code> method must not block the calling thread; if it does,
90 * all message I/O in MP will be blocked.
91 */
92 public void put(int i,
93 int item) {
94 throw new IndexOutOfBoundsException();
95 }
96
97 /**
98 * {@inheritDoc}
99 *
100 * Copy items from the given buffer to this buffer. The number of items
101 * copied is this buffer's length or <code>theSrc</code>'s length, whichever is
102 * smaller. If <code>theSrc</code> is this buffer, the <code>copy()</code> method
103 * does nothing.
104 * @exception ClassCastException (unchecked exception) Thrown if
105 * <code>theSrc</code>'s item data type is not the same as this buffer's item
106 * data type.
107 */
108 public void copy(Buf theSrc) {
109 }
110
111 /**
112 * {@inheritDoc}
113 *
114 * Create a buffer for performing parallel reduction using the given binary
115 * operation. The results of the reduction are placed into this buffer.
116 * <P>
117 * Operations performed on the returned reduction buffer have the same
118 * effect as operations performed on this buffer, except whenever a source
119 * item <I>S</I> is put into a destination item <I>D</I> in this buffer,
120 * <I>D</I> is set to <I>D op S</I>, that is, the reduction of <I>D</I> and
121 * <I>S</I> using the given binary operation (rather than just setting
122 * <I>D</I> to <I>S</I>).
123 * @exception ClassCastException (unchecked exception) Thrown if this
124 * buffer's element data type and the given binary operation's argument data
125 * type are not the same.
126 */
127 public Buf getReductionBuf(Op op) {
128 IntegerOp intop = (IntegerOp) op;
129 return this;
130 }
131
132 // Hidden operations.
133 /**
134 * {@inheritDoc}
135 *
136 * Send as many items as possible from this buffer to the given byte buffer.
137 * <P>
138 * The <code>sendItems()</code> method must not block the calling thread; if it
139 * does, all message I/O in MP will be blocked.
140 */
141 protected int sendItems(int i,
142 ByteBuffer buffer) {
143 return 0;
144 }
145
146 /**
147 * {@inheritDoc}
148 *
149 * Receive as many items as possible from the given byte buffer to this
150 * buffer.
151 * <P>
152 * The <code>receiveItems()</code> method must not block the calling thread; if
153 * it does, all message I/O in MP will be blocked.
154 */
155 protected int receiveItems(int i,
156 int num,
157 ByteBuffer buffer) {
158 return 0;
159 }
160
161 }