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1   //******************************************************************************
2   //
3   // File:    ObjectMatrixBuf.java
4   // Package: edu.rit.mp.buf
5   // Unit:    Class edu.rit.mp.buf.ObjectMatrixBuf
6   //
7   // This Java source file is copyright (C) 2009 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
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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 edu.rit.mp.Buf;
43  import edu.rit.mp.ObjectBuf;
44  import edu.rit.pj.reduction.ObjectOp;
45  import edu.rit.pj.reduction.Op;
46  import edu.rit.util.Arrays;
47  import edu.rit.util.Range;
48  
49  /**
50   * Class ObjectMatrixBuf provides a buffer for a matrix of object items sent or
51   * received using the Message Protocol (MP). The matrix row and column strides
52   * may be 1 or greater than 1. While an instance of class ObjectMatrixBuf may be
53   * constructed directly, normally you will use a factory method in class
54   * {@linkplain edu.rit.mp.ObjectBuf ObjectBuf}. See that class for further
55   * information.
56   *
57   * @param <T> Data type of the objects in the buffer.
58   * @author Alan Kaminsky
59   * @version 23-Mar-2009
60   */
61  @SuppressWarnings("unchecked")
62  public class ObjectMatrixBuf<T>
63          extends ObjectBuf<T> {
64  
65  // Hidden data members.
66      T[][] myMatrix;
67      Range myRowRange;
68      Range myColRange;
69      int myLowerRow;
70      int myRowCount;
71      int myRowStride;
72      int myLowerCol;
73      int myColCount;
74      int myColStride;
75  
76  // Exported constructors.
77      /**
78       * Construct a new object matrix buffer. It is assumed that the rows and
79       * columns of <code>theMatrix</code> are allocated and that each row of
80       * <code>theMatrix</code> has the same number of columns.
81       *
82       * @param theMatrix Matrix.
83       * @param theRowRange Range of rows to include.
84       * @param theColRange Range of columns to include.
85       */
86      public ObjectMatrixBuf(T[][] theMatrix,
87              Range theRowRange,
88              Range theColRange) {
89          super(theRowRange.length() * theColRange.length());
90          myMatrix = theMatrix;
91          myRowRange = theRowRange;
92          myColRange = theColRange;
93          myLowerRow = theRowRange.lb();
94          myRowCount = theRowRange.length();
95          myRowStride = theRowRange.stride();
96          myLowerCol = theColRange.lb();
97          myColCount = theColRange.length();
98          myColStride = theColRange.stride();
99      }
100 
101 // Exported operations.
102     /**
103      * {@inheritDoc}
104      *
105      * Obtain the given item from this buffer.
106      * <P>
107      * The <code>get()</code> method must not block the calling thread; if it does,
108      * all message I/O in MP will be blocked.
109      */
110     public T get(int i) {
111         return myMatrix[i2r(i) * myRowStride + myLowerRow][i2c(i) * myColStride + myLowerCol];
112     }
113 
114     /**
115      * Store the given item in this buffer.
116      * <P>
117      * The <code>put()</code> method must not block the calling thread; if it does,
118      * all message I/O in MP will be blocked.
119      *
120      * @param i Item index in the range 0 .. <code>length()</code>-1.
121      * @param item Item to be stored at index <code>i</code>.
122      */
123     public void put(int i,
124             T item) {
125         myMatrix[i2r(i) * myRowStride + myLowerRow][i2c(i) * myColStride + myLowerCol] = item;
126         reset();
127     }
128 
129     /**
130      * {@inheritDoc}
131      *
132      * Copy items from the given buffer to this buffer. The number of items
133      * copied is this buffer's length or <code>theSrc</code>'s length, whichever is
134      * smaller. If <code>theSrc</code> is this buffer, the <code>copy()</code> method
135      * does nothing.
136      * @exception ClassCastException (unchecked exception) Thrown if
137      * <code>theSrc</code>'s item data type is not the same as this buffer's item
138      * data type.
139      */
140     public void copy(Buf theSrc) {
141         if (theSrc == this) {
142         } else if (theSrc instanceof ObjectMatrixBuf) {
143             ObjectMatrixBuf<T> src = (ObjectMatrixBuf<T>) theSrc;
144             Arrays.copy(src.myMatrix, src.myRowRange, src.myColRange,
145                     this.myMatrix, this.myRowRange, this.myColRange);
146             reset();
147         } else {
148             ObjectBuf.defaultCopy((ObjectBuf<T>) theSrc, this);
149             reset();
150         }
151     }
152 
153     /**
154      * {@inheritDoc}
155      *
156      * Create a buffer for performing parallel reduction using the given binary
157      * operation. The results of the reduction are placed into this buffer.
158      * @exception ClassCastException (unchecked exception) Thrown if this
159      * buffer's element data type and the given binary operation's argument data
160      * type are not the same.
161      */
162     public Buf getReductionBuf(Op op) {
163         return new ObjectMatrixReductionBuf<T>(myMatrix, myRowRange, myColRange, (ObjectOp<T>) op, this);
164     }
165 
166 // Hidden operations.
167     /**
168      * Convert the given buffer index to a row index.
169      */
170     int i2r(int i) {
171         return myColCount == 0 ? i : i / myColCount;
172     }
173 
174     /**
175      * Convert the given buffer index to a column index.
176      */
177     int i2c(int i) {
178         return myColCount == 0 ? 0 : i % myColCount;
179     }
180 
181 }