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1   //******************************************************************************
2   //
3   // File:    LongArrayBuf_1.java
4   // Package: edu.rit.mp.buf
5   // Unit:    Class edu.rit.mp.buf.LongArrayBuf_1
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
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38  //
39  //******************************************************************************
40  package edu.rit.mp.buf;
41  
42  import java.nio.ByteBuffer;
43  import java.nio.LongBuffer;
44  
45  import edu.rit.mp.Buf;
46  import edu.rit.pj.reduction.LongOp;
47  import edu.rit.pj.reduction.Op;
48  import edu.rit.util.Range;
49  
50  /**
51   * Class LongArrayBuf_1 provides a buffer for an array of long items sent or
52   * received using the Message Protocol (MP). The array element stride must be 1.
53   * While an instance of class LongArrayBuf may be constructed directly, normally
54   * you will use a factory method in class {@linkplain
55   * edu.rit.mp.LongBuf LongBuf}. See that class for further information.
56   *
57   * @author Alan Kaminsky
58   * @version 25-Oct-2007
59   */
60  public class LongArrayBuf_1
61          extends LongArrayBuf {
62  
63  // Exported constructors.
64      /**
65       * Construct a new long array buffer.
66       *
67       * @param theArray Array.
68       * @param theRange Range of array elements to include in the buffer. The
69       * stride is assumed to be 1.
70       */
71      public LongArrayBuf_1(long[] theArray,
72              Range theRange) {
73          super(theArray, theRange);
74      }
75  
76  // Exported operations.
77      /**
78       * {@inheritDoc}
79       *
80       * Obtain the given item from this buffer.
81       * <P>
82       * The <code>get()</code> method must not block the calling thread; if it does,
83       * all message I/O in MP will be blocked.
84       */
85      public long get(int i) {
86          return myArray[myArrayOffset + i];
87      }
88  
89      /**
90       * {@inheritDoc}
91       *
92       * Store the given item in this buffer.
93       * <P>
94       * The <code>put()</code> method must not block the calling thread; if it does,
95       * all message I/O in MP will be blocked.
96       */
97      public void put(int i,
98              long item) {
99          myArray[myArrayOffset + i] = item;
100     }
101 
102     /**
103      * {@inheritDoc}
104      *
105      * Create a buffer for performing parallel reduction using the given binary
106      * operation. The results of the reduction are placed into this buffer.
107      * @exception ClassCastException (unchecked exception) Thrown if this
108      * buffer's element data type and the given binary operation's argument data
109      * type are not the same.
110      */
111     public Buf getReductionBuf(Op op) {
112         return new LongArrayReductionBuf_1(myArray, myRange, (LongOp) op);
113     }
114 
115 // Hidden operations.
116     /**
117      * {@inheritDoc}
118      *
119      * Send as many items as possible from this buffer to the given byte buffer.
120      * <P>
121      * The <code>sendItems()</code> method must not block the calling thread; if it
122      * does, all message I/O in MP will be blocked.
123      */
124     protected int sendItems(int i,
125             ByteBuffer buffer) {
126         LongBuffer longbuffer = buffer.asLongBuffer();
127         int n = Math.min(myLength - i, longbuffer.remaining());
128         longbuffer.put(myArray, myArrayOffset + i, n);
129         buffer.position(buffer.position() + 8 * n);
130         return n;
131     }
132 
133     /**
134      * {@inheritDoc}
135      *
136      * Receive as many items as possible from the given byte buffer to this
137      * buffer.
138      * <P>
139      * The <code>receiveItems()</code> method must not block the calling thread; if
140      * it does, all message I/O in MP will be blocked.
141      */
142     protected int receiveItems(int i,
143             int num,
144             ByteBuffer buffer) {
145         LongBuffer longbuffer = buffer.asLongBuffer();
146         int n = Math.min(num, Math.min(myLength - i, longbuffer.remaining()));
147         longbuffer.get(myArray, myArrayOffset + i, n);
148         buffer.position(buffer.position() + 8 * n);
149         return n;
150     }
151 
152 }