1 //******************************************************************************
2 //
3 // File: ByteArrayReductionBuf.java
4 // Package: edu.rit.mp.buf
5 // Unit: Class edu.rit.mp.buf.ByteArrayReductionBuf
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.ByteBuf;
46 import edu.rit.pj.reduction.ByteOp;
47 import edu.rit.pj.reduction.Op;
48 import edu.rit.pj.reduction.ReduceArrays;
49 import edu.rit.util.Range;
50
51 /**
52 * Class ByteArrayReductionBuf provides a reduction buffer for class {@linkplain
53 * ByteArrayBuf}.
54 *
55 * @author Alan Kaminsky
56 * @version 25-Oct-2007
57 */
58 class ByteArrayReductionBuf
59 extends ByteArrayBuf {
60
61 // Hidden data members.
62 ByteOp myOp;
63
64 // Exported constructors.
65 /**
66 * Construct a new byte array reduction buffer.
67 *
68 * @param theArray Array.
69 * @param theRange Range of array elements to include in the buffer.
70 * @param op Binary operation.
71 * @exception NullPointerException (unchecked exception) Thrown if
72 * <code>op</code> is null.
73 */
74 public ByteArrayReductionBuf(byte[] theArray,
75 Range theRange,
76 ByteOp op) {
77 super(theArray, theRange);
78 if (op == null) {
79 throw new NullPointerException("ByteArrayReductionBuf(): op is null");
80 }
81 myOp = op;
82 }
83
84 // Exported operations.
85 /**
86 * {@inheritDoc}
87 *
88 * Store the given item in this buffer.
89 * <P>
90 * The <code>put()</code> method must not block the calling thread; if it does,
91 * all message I/O in MP will be blocked.
92 */
93 public void put(int i,
94 byte item) {
95 int off = myArrayOffset + i * myStride;
96 myArray[off] = myOp.op(myArray[off], item);
97 }
98
99 /**
100 * {@inheritDoc}
101 *
102 * Copy items from the given buffer to this buffer. The number of items
103 * copied is this buffer's length or <code>theSrc</code>'s length, whichever is
104 * smaller. If <code>theSrc</code> is this buffer, the <code>copy()</code> method
105 * does nothing.
106 * @exception ClassCastException (unchecked exception) Thrown if
107 * <code>theSrc</code>'s item data type is not the same as this buffer's item
108 * data type.
109 */
110 public void copy(Buf theSrc) {
111 if (theSrc == this) {
112 } else if (theSrc instanceof ByteArrayBuf) {
113 ByteArrayBuf src = (ByteArrayBuf) theSrc;
114 ReduceArrays.reduce(src.myArray, src.myRange, this.myArray, this.myRange, myOp);
115 } else {
116 ByteBuf.defaultCopy((ByteBuf) theSrc, this);
117 }
118 }
119
120 /**
121 * {@inheritDoc}
122 *
123 * Create a buffer for performing parallel reduction using the given binary
124 * operation. The results of the reduction are placed into this buffer.
125 * @exception ClassCastException (unchecked exception) Thrown if this
126 * buffer's element data type and the given binary operation's argument data
127 * type are not the same.
128 */
129 public Buf getReductionBuf(Op op) {
130 throw new UnsupportedOperationException();
131 }
132
133 // Hidden operations.
134 /**
135 * {@inheritDoc}
136 *
137 * Receive as many items as possible from the given byte buffer to this
138 * buffer.
139 * <P>
140 * The <code>receiveItems()</code> method must not block the calling thread; if
141 * it does, all message I/O in MP will be blocked.
142 */
143 protected int receiveItems(int i,
144 int num,
145 ByteBuffer buffer) {
146 int index = i;
147 int off = myArrayOffset + i * myStride;
148 int max = Math.min(i + num, myLength);
149 while (index < max && buffer.remaining() >= 1) {
150 myArray[off] = myOp.op(myArray[off], buffer.get());
151 ++index;
152 off += myStride;
153 }
154 return index - i;
155 }
156
157 }