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1   //******************************************************************************
2   //
3   // File:    Unsigned16BitIntegerArrayBuf.java
4   // Package: edu.rit.mp.buf
5   // Unit:    Class edu.rit.mp.buf.Unsigned16BitIntegerArrayBuf
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
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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.Unsigned16BitIntegerBuf;
46  import edu.rit.pj.reduction.IntegerOp;
47  import edu.rit.pj.reduction.Op;
48  import edu.rit.util.Arrays;
49  import edu.rit.util.Range;
50  
51  /**
52   * Class Unsigned16BitIntegerArrayBuf provides a buffer for an array of unsigned
53   * 16-bit integer items sent or received using the Message Protocol (MP). The
54   * array element stride may be 1 or greater than 1. While an instance of class
55   * Unsigned16BitIntegerArrayBuf may be constructed directly, normally you will
56   * use a factory method in class {@linkplain edu.rit.mp.Unsigned16BitIntegerBuf
57   * Unsigned16BitIntegerBuf}. See that class for further information.
58   *
59   * @author Alan Kaminsky
60   * @version 26-Oct-2007
61   */
62  public class Unsigned16BitIntegerArrayBuf
63          extends Unsigned16BitIntegerBuf {
64  
65  // Hidden data members.
66      int[] myArray;
67      Range myRange;
68      int myArrayOffset;
69      int myStride;
70  
71  // Exported constructors.
72      /**
73       * Construct a new unsigned 16-bit integer array buffer.
74       *
75       * @param theArray Array.
76       * @param theRange Range of array elements to include in the buffer.
77       */
78      public Unsigned16BitIntegerArrayBuf(int[] theArray,
79              Range theRange) {
80          super(theRange.length());
81          myArray = theArray;
82          myRange = theRange;
83          myArrayOffset = theRange.lb();
84          myStride = theRange.stride();
85      }
86  
87  // Exported operations.
88      /**
89       * {@inheritDoc}
90       *
91       * Obtain the given item from this buffer.
92       * <P>
93       * The <code>get()</code> method must not block the calling thread; if it does,
94       * all message I/O in MP will be blocked.
95       */
96      public int get(int i) {
97          return myArray[myArrayOffset + i * myStride];
98      }
99  
100     /**
101      * {@inheritDoc}
102      *
103      * Store the given item in this buffer.
104      * <P>
105      * The <code>put()</code> method must not block the calling thread; if it does,
106      * all message I/O in MP will be blocked.
107      */
108     public void put(int i,
109             int item) {
110         myArray[myArrayOffset + i * myStride] = item;
111     }
112 
113     /**
114      * {@inheritDoc}
115      *
116      * Copy items from the given buffer to this buffer. The number of items
117      * copied is this buffer's length or <code>theSrc</code>'s length, whichever is
118      * smaller. If <code>theSrc</code> is this buffer, the <code>copy()</code> method
119      * does nothing.
120      * @exception ClassCastException (unchecked exception) Thrown if
121      * <code>theSrc</code>'s item data type is not the same as this buffer's item
122      * data type.
123      */
124     public void copy(Buf theSrc) {
125         if (theSrc == this) {
126         } else if (theSrc instanceof Unsigned16BitIntegerArrayBuf) {
127             Unsigned16BitIntegerArrayBuf src
128                     = (Unsigned16BitIntegerArrayBuf) theSrc;
129             Arrays.copy(src.myArray, src.myRange, this.myArray, this.myRange);
130         } else {
131             Unsigned16BitIntegerBuf.defaultCopy((Unsigned16BitIntegerBuf) theSrc, this);
132         }
133     }
134 
135     /**
136      * {@inheritDoc}
137      *
138      * Create a buffer for performing parallel reduction using the given binary
139      * operation. The results of the reduction are placed into this buffer.
140      * @exception ClassCastException (unchecked exception) Thrown if this
141      * buffer's element data type and the given binary operation's argument data
142      * type are not the same.
143      */
144     public Buf getReductionBuf(Op op) {
145         return new Unsigned16BitIntegerArrayReductionBuf(myArray, myRange, (IntegerOp) op);
146     }
147 
148 // Hidden operations.
149     /**
150      * {@inheritDoc}
151      *
152      * Send as many items as possible from this buffer to the given byte buffer.
153      * <P>
154      * The <code>sendItems()</code> method must not block the calling thread; if it
155      * does, all message I/O in MP will be blocked.
156      */
157     protected int sendItems(int i,
158             ByteBuffer buffer) {
159         int index = i;
160         int off = myArrayOffset + i * myStride;
161         while (index < myLength && buffer.remaining() >= 2) {
162             buffer.putShort((short) myArray[off]);
163             ++index;
164             off += myStride;
165         }
166         return index - i;
167     }
168 
169     /**
170      * {@inheritDoc}
171      *
172      * Receive as many items as possible from the given byte buffer to this
173      * buffer.
174      * <P>
175      * The <code>receiveItems()</code> method must not block the calling thread; if
176      * it does, all message I/O in MP will be blocked.
177      */
178     protected int receiveItems(int i,
179             int num,
180             ByteBuffer buffer) {
181         int index = i;
182         int off = myArrayOffset + i * myStride;
183         int max = Math.min(i + num, myLength);
184         while (index < max && buffer.remaining() >= 2) {
185             myArray[off] = buffer.getShort() & 0xFFFF;
186             ++index;
187             off += myStride;
188         }
189         return index - i;
190     }
191 
192 }