1 /*
2  * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4  *
5  * This code is free software; you can redistribute it and/or modify it
6  * under the terms of the GNU General Public License version 2 only, as
7  * published by the Free Software Foundation.  Oracle designates this
8  * particular file as subject to the "Classpath" exception as provided
9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20  *
21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22  * or visit www.oracle.com if you need additional information or have any
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24  */
25 package sun.misc;
26 
27 import java.util.concurrent.ThreadLocalRandom;
28 
29 /**
30  * Hashing utilities.
31  *
32  * Little endian implementations of Murmur3 hashing.
33  */
34 public class Hashing {
35 
36     /**
37      * Static utility methods only.
38      */
Hashing()39     private Hashing() {
40         throw new Error("No instances");
41     }
42 
43     // Spread bits to regularize both segment and index locations,
44     // using variant of single-word Wang/Jenkins hash.
45     //
46     // Based on commit 1424a2a1a9fc53dc8b859a77c02c924.
singleWordWangJenkinsHash(Object k)47     public static int singleWordWangJenkinsHash(Object k) {
48         int h = k.hashCode();
49 
50         h += (h <<  15) ^ 0xffffcd7d;
51         h ^= (h >>> 10);
52         h += (h <<   3);
53         h ^= (h >>>  6);
54         h += (h <<   2) + (h << 14);
55         return h ^ (h >>> 16);
56     }
57 }
58