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1   //******************************************************************************
2   //
3   // File:    Signed16BitIntegerMatrixReductionBuf.java
4   // Package: edu.rit.mp.buf
5   // Unit:    Class edu.rit.mp.buf.Signed16BitIntegerMatrixReductionBuf
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
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21  // combined work based on this library. Thus, the terms and conditions of the GNU
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39  //******************************************************************************
40  package edu.rit.mp.buf;
41  
42  import java.nio.ByteBuffer;
43  import java.nio.ShortBuffer;
44  
45  import edu.rit.mp.Buf;
46  import edu.rit.mp.Signed16BitIntegerBuf;
47  import edu.rit.pj.reduction.IntegerOp;
48  import edu.rit.pj.reduction.Op;
49  import edu.rit.pj.reduction.ReduceArrays;
50  import edu.rit.util.Range;
51  
52  /**
53   * Class Signed16BitIntegerMatrixReductionBuf provides a reduction buffer for
54   * class {@linkplain Signed16BitIntegerMatrixBuf}.
55   *
56   * @author Alan Kaminsky
57   * @version 05-Apr-2009
58   */
59  class Signed16BitIntegerMatrixReductionBuf
60          extends Signed16BitIntegerMatrixBuf {
61  
62  // Hidden data members.
63      IntegerOp myOp;
64  
65  // Exported constructors.
66      /**
67       * Construct a new signed 16-bit integer matrix reduction buffer. It is
68       * assumed that the rows and columns of <code>theMatrix</code> are allocated and
69       * that each row of <code>theMatrix</code> has the same number of columns.
70       *
71       * @param theMatrix Matrix.
72       * @param theRowRange Range of rows to include.
73       * @param theColRange Range of columns to include.
74       * @param op Binary operation.
75       * @exception NullPointerException (unchecked exception) Thrown if
76       * <code>op</code> is null.
77       */
78      public Signed16BitIntegerMatrixReductionBuf(int[][] theMatrix,
79              Range theRowRange,
80              Range theColRange,
81              IntegerOp op) {
82          super(theMatrix, theRowRange, theColRange);
83          if (op == null) {
84              throw new NullPointerException("Signed16BitIntegerMatrixReductionBuf(): op is null");
85          }
86          myOp = op;
87      }
88  
89  // Exported operations.
90      /**
91       * {@inheritDoc}
92       *
93       * Store the given item in this buffer.
94       * <P>
95       * The <code>put()</code> method must not block the calling thread; if it does,
96       * all message I/O in MP will be blocked.
97       */
98      public void put(int i,
99              int item) {
100         int row = (i / myColCount) * myRowStride + myLowerRow;
101         int col = (i % myColCount) * myColStride + myLowerCol;
102         myMatrix[row][col] = myOp.op(myMatrix[row][col], item);
103     }
104 
105     /**
106      * {@inheritDoc}
107      *
108      * Copy items from the given buffer to this buffer. The number of items
109      * copied is this buffer's length or <code>theSrc</code>'s length, whichever is
110      * smaller. If <code>theSrc</code> is this buffer, the <code>copy()</code> method
111      * does nothing.
112      * @exception ClassCastException (unchecked exception) Thrown if
113      * <code>theSrc</code>'s item data type is not the same as this buffer's item
114      * data type.
115      */
116     public void copy(Buf theSrc) {
117         if (theSrc == this) {
118         } else if (theSrc instanceof Signed16BitIntegerMatrixBuf) {
119             Signed16BitIntegerMatrixBuf src
120                     = (Signed16BitIntegerMatrixBuf) theSrc;
121             ReduceArrays.reduce(src.myMatrix, src.myRowRange, src.myColRange,
122                     this.myMatrix, this.myRowRange, this.myColRange,
123                     myOp);
124         } else {
125             Signed16BitIntegerBuf.defaultCopy((Signed16BitIntegerBuf) theSrc, this);
126         }
127     }
128 
129     /**
130      * {@inheritDoc}
131      *
132      * Create a buffer for performing parallel reduction using the given binary
133      * operation. The results of the reduction are placed into this buffer.
134      * @exception ClassCastException (unchecked exception) Thrown if this
135      * buffer's element data type and the given binary operation's argument data
136      * type are not the same.
137      */
138     public Buf getReductionBuf(Op op) {
139         throw new UnsupportedOperationException();
140     }
141 
142 // Hidden operations.
143     /**
144      * {@inheritDoc}
145      *
146      * Receive as many items as possible from the given byte buffer to this
147      * buffer.
148      * <P>
149      * The <code>receiveItems()</code> method must not block the calling thread; if
150      * it does, all message I/O in MP will be blocked.
151      */
152     protected int receiveItems(int i,
153             int num,
154             ByteBuffer buffer) {
155         ShortBuffer shortbuffer = buffer.asShortBuffer();
156         num = Math.min(num, shortbuffer.remaining());
157         int n = 0;
158         int r = i2r(i);
159         int row = r * myRowStride + myLowerRow;
160         int c = i2c(i);
161         int col = c * myColStride + myLowerCol;
162         int ncols = Math.min(myColCount - c, num);
163         while (r < myRowCount && ncols > 0) {
164             int[] myMatrix_row = myMatrix[row];
165             for (c = 0; c < ncols; ++c) {
166                 myMatrix_row[col]
167                         = myOp.op(myMatrix_row[col], shortbuffer.get());
168                 col += myColStride;
169             }
170             num -= ncols;
171             n += ncols;
172             ++r;
173             row += myRowStride;
174             col = myLowerCol;
175             ncols = Math.min(myColCount, num);
176         }
177         buffer.position(buffer.position() + 2 * n);
178         return n;
179     }
180 
181 }