1 /** 2 * JDBM LICENSE v1.00 3 * 4 * Redistribution and use of this software and associated documentation 5 * ("Software"), with or without modification, are permitted provided 6 * that the following conditions are met: 7 * 8 * 1. Redistributions of source code must retain copyright 9 * statements and notices. Redistributions must also contain a 10 * copy of this document. 11 * 12 * 2. Redistributions in binary form must reproduce the 13 * above copyright notice, this list of conditions and the 14 * following disclaimer in the documentation and/or other 15 * materials provided with the distribution. 16 * 17 * 3. The name "JDBM" must not be used to endorse or promote 18 * products derived from this Software without prior written 19 * permission of Cees de Groot. For written permission, 20 * please contact cg@cdegroot.com. 21 * 22 * 4. Products derived from this Software may not be called "JDBM" 23 * nor may "JDBM" appear in their names without prior written 24 * permission of Cees de Groot. 25 * 26 * 5. Due credit should be given to the JDBM Project 27 * (http://jdbm.sourceforge.net/). 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE JDBM PROJECT AND CONTRIBUTORS 30 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT 31 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 32 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 33 * CEES DE GROOT OR ANY CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 34 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 35 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 36 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 38 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 39 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 40 * OF THE POSSIBILITY OF SUCH DAMAGE. 41 * 42 * Copyright 2000 (C) Cees de Groot. All Rights Reserved. 43 * Contributions are Copyright (C) 2000 by their associated contributors. 44 * 45 * $Id: PhysicalRowId.java,v 1.1 2000/05/06 00:00:31 boisvert Exp $ 46 */ 47 48 package jdbm.recman; 49 50 /** 51 * A physical rowid is nothing else than a pointer to a physical location 52 * in a file - a (block, offset) tuple. 53 * <P> 54 * <B>Note</B>: The fact that the offset is modelled as a short limits 55 * the block size to 32k. 56 */ 57 class PhysicalRowId { 58 // offsets 59 private static final short O_BLOCK = 0; // long block 60 private static final short O_OFFSET = Magic.SZ_LONG; // short offset 61 static final int SIZE = O_OFFSET + Magic.SZ_SHORT; 62 63 // my block and the position within the block 64 BlockIo block; 65 short pos; 66 67 /** 68 * Constructs a physical rowid from the indicated data starting at 69 * the indicated position. 70 */ 71 PhysicalRowId(BlockIo block, short pos) { 72 this.block = block; 73 this.pos = pos; 74 } 75 76 /** Returns the block number */ 77 long getBlock() { 78 return block.readLong(pos + O_BLOCK); 79 } 80 81 /** Sets the block number */ 82 void setBlock(long value) { 83 block.writeLong(pos + O_BLOCK, value); 84 } 85 86 /** Returns the offset */ 87 short getOffset() { 88 return block.readShort(pos + O_OFFSET); 89 } 90 91 /** Sets the offset */ 92 void setOffset(short value) { 93 block.writeShort(pos + O_OFFSET, value); 94 } 95 }