org.fuzzydb.util.BitUtils Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of org.fuzzydb.util Show documentation

Contains classes not specific to fuzzydb implementation which could be used in any implementation of fuzzy matching, or as general utility classes such as those in the geo package.

The newest version!

/******************************************************************************
 * Copyright (c) 2004-2008 Whirlwind Match Limited. All rights reserved.
 *
 * This is open source software; you can use, redistribute and/or modify
 * it under the terms of the Open Software Licence v 3.0 as published by the 
 * Open Source Initiative.
 *
 * You should have received a copy of the Open Software Licence along with this
 * application. if not, contact the Open Source Initiative (www.opensource.org)
 *****************************************************************************/
package org.fuzzydb.util;


public class BitUtils {

	/**
	 * Get the indexes of the values
	 */
	public static short[] bitFieldToIndexArray(long bitfield) {
		int entries = countBitsSet( bitfield );
		short[] vals = new short[entries];
		int currEntry = 0;
		for (short i = 0; i < Long.SIZE; i++) {
			if ((bitfield & 0x01) != 0){
				vals[currEntry++] = i;
			}
			bitfield >>>= 1;
		}
		return vals;
	}

	/**
	 * Get the indexes of the values
	 */
	public static short[] bitFieldToIndexArray(int bitfield) {
		int entries = countBitsSet( bitfield );
		short[] vals = new short[entries];
		int currEntry = 0;
		for (short i = 0; i < Long.SIZE; i++) {
			if ((bitfield & 0x01) != 0){
				vals[currEntry++] = i;
			}
			bitfield >>>= 1;
		}
		return vals;
	}

	// NOTE: Diff version for Int, as otherwise will get top bits filled on cast from int -> long
	public static int countBitsSet(int bitfield) {
		int count = 0;
		for (short i = 0; i < Integer.SIZE; i++) {
			if ((bitfield & 0x01) != 0){
				count++;
			}
			bitfield >>>= 1;
		}
		return count;
	}

	public static int countBitsSet(long bitfield) {
		int count = 0;
		for (short i = 0; i < Long.SIZE; i++) {
			if ((bitfield & 0x01) != 0){
				count++;
			}
			bitfield >>>= 1;
		}
		return count;
	}

	/**
	 * Encode a set of shorts into a bitfield as a long
	 */
	public static long indexArrayToLongBits(short[] values) {
		long bitfield = 0;
		for (int i = 0; i < values.length; i++) {
			bitfield |= 0x01 << values[i];
		}
		return bitfield;
	}

	public static int indexArrayToIntBits(short[] values) {
		int bitfield = 0;
		for (int i = 0; i < values.length; i++) {
			bitfield |= 0x01 << values[i];
		}
		return bitfield;
	}

}