1 //******************************************************************************
2 //
3 // File: SharedUnsigned8BitIntegerArrayBuf.java
4 // Package: edu.rit.mp.buf
5 // Unit: Class edu.rit.mp.buf.SharedUnsigned8BitIntegerArrayBuf
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.Unsigned8BitIntegerBuf;
46 import edu.rit.pj.reduction.IntegerOp;
47 import edu.rit.pj.reduction.Op;
48 import edu.rit.pj.reduction.SharedIntegerArray;
49 import edu.rit.util.Range;
50
51 /**
52 * Class SharedUnsigned8BitIntegerArrayBuf provides a buffer for a multiple
53 * thread safe array of unsigned 8-bit integer items sent or received using the
54 * Message Protocol (MP). The array element stride may be 1 or greater than 1.
55 * While an instance of class SharedUnsigned8BitIntegerArrayBuf may be
56 * constructed directly, normally you will use a factory method in class
57 * {@linkplain edu.rit.mp.Unsigned8BitIntegerBuf Unsigned8BitIntegerBuf}. See
58 * that class for further information.
59 *
60 * @author Alan Kaminsky
61 * @version 26-Oct-2007
62 */
63 public class SharedUnsigned8BitIntegerArrayBuf
64 extends Unsigned8BitIntegerBuf {
65
66 // Hidden data members.
67 SharedIntegerArray myArray;
68 Range myRange;
69 int myArrayOffset;
70 int myStride;
71
72 // Exported constructors.
73 /**
74 * Construct a new shared unsigned 8-bit integer array buffer.
75 *
76 * @param theArray Shared array.
77 * @param theRange Range of array elements to include in the buffer.
78 */
79 public SharedUnsigned8BitIntegerArrayBuf(SharedIntegerArray theArray,
80 Range theRange) {
81 super(theRange.length());
82 myArray = theArray;
83 myRange = theRange;
84 myArrayOffset = theRange.lb();
85 myStride = theRange.stride();
86 }
87
88 // Exported operations.
89 /**
90 * {@inheritDoc}
91 *
92 * Obtain the given item from this buffer.
93 * <P>
94 * The <code>get()</code> method must not block the calling thread; if it does,
95 * all message I/O in MP will be blocked.
96 */
97 public int get(int i) {
98 return myArray.get(myArrayOffset + i * myStride);
99 }
100
101 /**
102 * {@inheritDoc}
103 *
104 * Store the given item in this buffer.
105 * <P>
106 * The <code>put()</code> method must not block the calling thread; if it does,
107 * all message I/O in MP will be blocked.
108 */
109 public void put(int i,
110 int item) {
111 myArray.set(myArrayOffset + i * myStride, item);
112 }
113
114 /**
115 * {@inheritDoc}
116 *
117 * Create a buffer for performing parallel reduction using the given binary
118 * operation. The results of the reduction are placed into this buffer.
119 * @exception ClassCastException (unchecked exception) Thrown if this
120 * buffer's element data type and the given binary operation's argument data
121 * type are not the same.
122 */
123 public Buf getReductionBuf(Op op) {
124 return new SharedUnsigned8BitIntegerArrayReductionBuf(myArray, myRange, (IntegerOp) op);
125 }
126
127 // Hidden operations.
128 /**
129 * {@inheritDoc}
130 *
131 * Send as many items as possible from this buffer to the given byte buffer.
132 * <P>
133 * The <code>sendItems()</code> method must not block the calling thread; if it
134 * does, all message I/O in MP will be blocked.
135 */
136 protected int sendItems(int i,
137 ByteBuffer buffer) {
138 int index = i;
139 int off = myArrayOffset + i * myStride;
140 while (index < myLength && buffer.remaining() >= 1) {
141 buffer.put((byte) myArray.get(off));
142 ++index;
143 off += myStride;
144 }
145 return index - i;
146 }
147
148 /**
149 * {@inheritDoc}
150 *
151 * Receive as many items as possible from the given byte buffer to this
152 * buffer.
153 * <P>
154 * The <code>receiveItems()</code> method must not block the calling thread; if
155 * it does, all message I/O in MP will be blocked.
156 */
157 protected int receiveItems(int i,
158 int num,
159 ByteBuffer buffer) {
160 int index = i;
161 int off = myArrayOffset + i * myStride;
162 int max = Math.min(i + num, myLength);
163 while (index < max && buffer.remaining() >= 1) {
164 myArray.set(off, buffer.get() & 0xFF);
165 ++index;
166 off += myStride;
167 }
168 return index - i;
169 }
170
171 }