Java Hash Calculate hash64(final byte[] data, int length)

Description

hash

License

Apache License

Declaration

public static long hash64(final byte[] data, int length) 

Method Source Code

//package com.java2s;
/**/*from  ww  w. j a  v a2  s  . c  o m*/
 * Copyright (C) 2014-2015 LinkedIn Corp. (pinot-core@linkedin.com)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

public class Main {
    public static long hash64(final byte[] data, int length) {
        // Default seed is 0xe17a1465.
        return hash64(data, length, 0xe17a1465);
    }

    public static long hash64(final byte[] data, int length, int seed) {
        final long m = 0xc6a4a7935bd1e995L;
        final int r = 47;

        long h = (seed & 0xffffffffl) ^ (length * m);

        int length8 = length / 8;

        for (int i = 0; i < length8; i++) {
            final int i8 = i * 8;
            long k = ((long) data[i8 + 0] & 0xff) + (((long) data[i8 + 1] & 0xff) << 8)
                    + (((long) data[i8 + 2] & 0xff) << 16) + (((long) data[i8 + 3] & 0xff) << 24)
                    + (((long) data[i8 + 4] & 0xff) << 32) + (((long) data[i8 + 5] & 0xff) << 40)
                    + (((long) data[i8 + 6] & 0xff) << 48) + (((long) data[i8 + 7] & 0xff) << 56);

            k *= m;
            k ^= k >>> r;
            k *= m;

            h ^= k;
            h *= m;
        }

        switch (length % 8) {
        case 7:
            h ^= (long) (data[(length & ~7) + 6] & 0xff) << 48;
        case 6:
            h ^= (long) (data[(length & ~7) + 5] & 0xff) << 40;
        case 5:
            h ^= (long) (data[(length & ~7) + 4] & 0xff) << 32;
        case 4:
            h ^= (long) (data[(length & ~7) + 3] & 0xff) << 24;
        case 3:
            h ^= (long) (data[(length & ~7) + 2] & 0xff) << 16;
        case 2:
            h ^= (long) (data[(length & ~7) + 1] & 0xff) << 8;
        case 1:
            h ^= (long) (data[length & ~7] & 0xff);
            h *= m;
        }
        ;

        h ^= h >>> r;
        h *= m;
        h ^= h >>> r;
        return h;
    }
}

Related

1. hash1(Object a)
2. hash16(int hash)
3. hash3(int hash, Object x, Object y, Object z)
4. Hash32(byte[] v, int iStart, int iLength)
5. hash32shiftmult(int k)
6. hash64To32(long lg)
7. hash64to32(long v)
8. hashAdd(final int left, final int right)
9. hashAll(Object[] array)