// **********************************************************************
//
// <copyright>
//
// BBN Technologies
// 10 Moulton Street
// Cambridge, MA 02138
// (617) 873-8000
//
// Copyright (C) BBNT Solutions LLC. All rights reserved.
//
// </copyright>
// **********************************************************************
//
// $Source: /cvs/distapps/openmap/src/openmap/com/bbn/openmap/layer/vpf/DcwVariableLengthIndexFile.java,v $
// $RCSfile: DcwVariableLengthIndexFile.java,v $
// $Revision: 1.2.2.2 $
// $Date: 2005/08/09 21:17:51 $
// $Author: dietrick $
//
// **********************************************************************
package com.bbn.openmap.layer.vpf;
import java.io.IOException;
import com.bbn.openmap.io.FormatException;
import com.bbn.openmap.io.BinaryFile;
import com.bbn.openmap.io.BinaryBufferedFile;
/**
* Read in a VPF variable length index file, and allows access to
* individual records.
*/
public class DcwVariableLengthIndexFile {
/** holds all the offset,size pairs */
final private int offsettable[];
/** the number of records */
final private int recordCount;
/** the end of the file offset */
final private int endOfFileOffset;
/**
* Construct a new index file.
*
* @param filename the name of the file to read in.
* @param msbfirst the byte order of the file to be read.
* @exception FormatException some error was encountered in trying
* to read the file.
*/
public DcwVariableLengthIndexFile(String filename, boolean msbfirst)
throws FormatException, IOException {
this(new BinaryBufferedFile(filename), msbfirst);
}
/**
* Construct a new index file.
*
* @param inputstream BinaryBufferedFile handle.
* @param msbfirst the byte order of the file to be read.
* @exception FormatException some error was encountered in trying
* to read the file.
*/
public DcwVariableLengthIndexFile(BinaryFile inputstream, boolean msbfirst)
throws FormatException {
try {
inputstream.byteOrder(msbfirst);
recordCount = inputstream.readInteger();
/*int HeaderLength = */inputstream.readInteger();
offsettable = new int[recordCount * 2];
inputstream.readIntegerArray(offsettable, 0, recordCount * 2);
endOfFileOffset = offsettable[offsettable.length - 2]
+ offsettable[offsettable.length - 1];
inputstream.close();
// com.bbn.openmap.util.Debug.output("VLI.init(): number
// of entries(" + recordCount +
// ") HeaderLength(" + HeaderLength + ")");
} catch (IOException i) {
throw new FormatException("IOException with "
+ inputstream.getName() + ": " + i.getMessage());
}
}
/**
* get the offset byte offset of the record in the associated
* table file. If recordNumber is greater than the number of
* records, this returns the offset of the end-of-file.
*
* @param recordNumber the record to retrieve the offset for
*/
public int recordOffset(int recordNumber) {
return (recordCount < recordNumber) ? endOfFileOffset
: offsettable[(recordNumber - 1) * 2];
}
/**
* get the size of the record in the associated table file If
* recordNumber is greater than the number of records, this
* returns a record size of 0.
*
* @param recordNumber the record to retrieve the offset for
*/
public int recordSize(int recordNumber) {
return (recordCount < recordNumber) ? 0
: offsettable[(recordNumber - 1) * 2 + 1];
}
/** get the number of records in the index file */
public int getRecordCount() {
return recordCount;
}
/** close the associated input file */
public void close() {}
}