Java Murmur Hash murmurhash3x8632(byte[] data, int offset, int len, int seed)

Description

This code is public domain.

License

Open Source License

Declaration

public static int murmurhash3x8632(byte[] data, int offset, int len,
        int seed) 

Method Source Code

//package com.java2s;
/*/* w ww.  j  a v a 2s  .  c o m*/
 * *****************************************************************************
 *      Cloud Foundry
 *      Copyright (c) [2009-2015] Pivotal Software, Inc. All Rights Reserved.
 *      This product is licensed to you under the Apache License, Version 2.0 (the "License").
 *      You may not use this product except in compliance with the License.
 *
 *      This product includes a number of subcomponents with
 *      separate copyright notices and license terms. Your use of these
 *      subcomponents is subject to the terms and conditions of the
 *      subcomponent's license, as noted in the LICENSE file.
 * *****************************************************************************
 */

public class Main {
    /**
     * This code is public domain.
     *
     *  The MurmurHash3 algorithm was created by Austin Appleby and put into the public domain.
     *  @see <a href="http://code.google.com/p/smhasher">http://code.google.com/p/smhasher</a>
     *  @see <a href="https://github.com/yonik/java_util/blob/master/src/util/hash/MurmurHash3.java">https://github.com/yonik/java_util/blob/master/src/util/hash/MurmurHash3.java</a>
     */
    public static int murmurhash3x8632(byte[] data, int offset, int len,
            int seed) {

        int c1 = 0xcc9e2d51;
        int c2 = 0x1b873593;

        int h1 = seed;
        int roundedEnd = offset + (len & 0xfffffffc); // round down to 4 byte block

        for (int i = offset; i < roundedEnd; i += 4) {
            // little endian load order
            int k1 = (data[i] & 0xff) | ((data[i + 1] & 0xff) << 8)
                    | ((data[i + 2] & 0xff) << 16) | (data[i + 3] << 24);
            k1 *= c1;
            k1 = (k1 << 15) | (k1 >>> 17); // ROTL32(k1,15);
            k1 *= c2;

            h1 ^= k1;
            h1 = (h1 << 13) | (h1 >>> 19); // ROTL32(h1,13);
            h1 = h1 * 5 + 0xe6546b64;
        }

        // tail
        int k1 = 0;

        switch (len & 0x03) {
        case 3:
            k1 = (data[roundedEnd + 2] & 0xff) << 16;
            // fallthrough
        case 2:
            k1 |= (data[roundedEnd + 1] & 0xff) << 8;
            // fallthrough
        case 1:
            k1 |= data[roundedEnd] & 0xff;
            k1 *= c1;
            k1 = (k1 << 15) | (k1 >>> 17); // ROTL32(k1,15);
            k1 *= c2;
            h1 ^= k1;
        default:
        }

        // finalization
        h1 ^= len;

        // fmix(h1);
        h1 ^= h1 >>> 16;
        h1 *= 0x85ebca6b;
        h1 ^= h1 >>> 13;
        h1 *= 0xc2b2ae35;
        h1 ^= h1 >>> 16;

        return h1;
    }
}

Related

1. murmurhash2_64(final byte[] data, int length, int seed)
2. murmurHash3(int k)
3. murmurHash3(int x)
4. murmurHash3(int x)
5. MurmurHash3_fmix(int k)
6. murmurMix(long h)
7. murmurRehash(final int hash)