//
// Copyright (C) 2006 United States Government as represented by the
// Administrator of the National Aeronautics and Space Administration
// (NASA). All Rights Reserved.
//
// This software is distributed under the NASA Open Source Agreement
// (NOSA), version 1.3. The NOSA has been approved by the Open Source
// Initiative. See the file NOSA-1.3-JPF at the top of the distribution
// directory tree for the complete NOSA document.
//
// THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
// KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
// LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
// SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
// A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
// THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
// DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
//
package gov.nasa.jpf.util;
/**
* object to compute complex hash values that can be accumulated and
* delegated (to aggregates etc.)
* used to obtain hashcodes for states
*/
public class HashData {
private static final int poly = 0x88888EEF;
private int m = -1;
public void reset() {
m = -1;
}
public int getValue () {
return (m >>> 4) ^ (m & 15);
}
public void add (int value) {
if (m < 0) {
m += m;
m ^= poly;
} else {
m += m;
}
m ^= value;
}
public void add (long value){
add((int)(value ^ (value >>> 32)));
}
public void add (Object o) {
if (o != null) {
add(o.hashCode());
}
}
public void add (boolean b) {
// a clear case of '42', but that's the "official" boolean hashing
add(b ? 1231 : 1237);
}
}