1 //****************************************************************************** 2 // 3 // File: EmptyUnsigned16BitIntegerBuf.java 4 // Package: edu.rit.mp.buf 5 // Unit: Class edu.rit.mp.buf.EmptyUnsigned16BitIntegerBuf 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.Unsigned16BitIntegerBuf; 46 import edu.rit.pj.reduction.IntegerOp; 47 import edu.rit.pj.reduction.Op; 48 49 /** 50 * Class EmptyUnsigned16BitIntegerBuf provides an unsigned 16-bit integer buffer 51 * that contains no items for messages using the Message Protocol (MP). When a 52 * message is sent from an EmptyUnsigned16BitIntegerBuf, the message item type 53 * is unsigned 16-bit <code>int</code> and the message length is 0. When a message 54 * is received into an EmptyUnsigned16BitIntegerBuf, the message item type must 55 * be unsigned 16-bit <code>int</code>, but all items in the message are discarded. 56 * 57 * @author Alan Kaminsky 58 * @version 19-Nov-2007 59 */ 60 public class EmptyUnsigned16BitIntegerBuf 61 extends Unsigned16BitIntegerBuf { 62 63 // Exported constructors. 64 /** 65 * Construct a new empty unsigned 16-bit integer buffer. 66 */ 67 public EmptyUnsigned16BitIntegerBuf() { 68 super(0); 69 } 70 71 // Exported operations. 72 /** 73 * {@inheritDoc} 74 * 75 * Obtain the given item from this buffer. 76 * <P> 77 * The <code>get()</code> method must not block the calling thread; if it does, 78 * all message I/O in MP will be blocked. 79 */ 80 public int get(int i) { 81 throw new IndexOutOfBoundsException(); 82 } 83 84 /** 85 * {@inheritDoc} 86 * 87 * Store the given item in this buffer. 88 * <P> 89 * The <code>put()</code> method must not block the calling thread; if it does, 90 * all message I/O in MP will be blocked. 91 */ 92 public void put(int i, 93 int item) { 94 throw new IndexOutOfBoundsException(); 95 } 96 97 /** 98 * {@inheritDoc} 99 * 100 * Copy items from the given buffer to this buffer. The number of items 101 * copied is this buffer's length or <code>theSrc</code>'s length, whichever is 102 * smaller. If <code>theSrc</code> is this buffer, the <code>copy()</code> method 103 * does nothing. 104 * @exception ClassCastException (unchecked exception) Thrown if 105 * <code>theSrc</code>'s item data type is not the same as this buffer's item 106 * data type. 107 */ 108 public void copy(Buf theSrc) { 109 } 110 111 /** 112 * {@inheritDoc} 113 * 114 * Create a buffer for performing parallel reduction using the given binary 115 * operation. The results of the reduction are placed into this buffer. 116 * <P> 117 * Operations performed on the returned reduction buffer have the same 118 * effect as operations performed on this buffer, except whenever a source 119 * item <I>S</I> is put into a destination item <I>D</I> in this buffer, 120 * <I>D</I> is set to <I>D op S</I>, that is, the reduction of <I>D</I> and 121 * <I>S</I> using the given binary operation (rather than just setting 122 * <I>D</I> to <I>S</I>). 123 * @exception ClassCastException (unchecked exception) Thrown if this 124 * buffer's element data type and the given binary operation's argument data 125 * type are not the same. 126 */ 127 public Buf getReductionBuf(Op op) { 128 IntegerOp intop = (IntegerOp) op; 129 return this; 130 } 131 132 // Hidden operations. 133 /** 134 * {@inheritDoc} 135 * 136 * Send as many items as possible from this buffer to the given byte buffer. 137 * <P> 138 * The <code>sendItems()</code> method must not block the calling thread; if it 139 * does, all message I/O in MP will be blocked. 140 */ 141 protected int sendItems(int i, 142 ByteBuffer buffer) { 143 return 0; 144 } 145 146 /** 147 * {@inheritDoc} 148 * 149 * Receive as many items as possible from the given byte buffer to this 150 * buffer. 151 * <P> 152 * The <code>receiveItems()</code> method must not block the calling thread; if 153 * it does, all message I/O in MP will be blocked. 154 */ 155 protected int receiveItems(int i, 156 int num, 157 ByteBuffer buffer) { 158 return 0; 159 } 160 161 }