1 /*

     2  * Copyright (c) 2017, 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.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 package sun.jvm.hotspot.memory;

    26 

    27 public class AltHashing {

    28     public static long murmur3_32(long seed, byte[] data) {

    29       long h1 = seed;

    30       int len = data.length;

    31       int count = len;

    32 

    33       int offset = 0;

    34 

    35       // body

    36       while (count >= 4) {

    37           long k1 = (data[offset] & 0x0FF)

    38               | (data[offset + 1] & 0x0FF) << 8

    39               | (data[offset + 2] & 0x0FF) << 16

    40               | data[offset + 3] << 24;

    41 

    42           count -= 4;

    43           offset += 4;

    44 

    45           k1 *= 0xcc9e2d51;

    46           k1 = Integer.rotateLeft((int)k1, 15);

    47           k1 *= 0x1b873593;

    48           k1 &= 0xFFFFFFFFL;

    49 

    50           h1 ^= k1;

    51           h1 = Integer.rotateLeft((int)h1, 13);

    52           h1 = h1 * 5 + 0xe6546b64;

    53           h1 &= 0xFFFFFFFFL;

    54       }

    55 

    56       //tail

    57       if (count > 0) {

    58           long k1 = 0;

    59 

    60           switch (count) {

    61               case 3:

    62                   k1 ^= (data[offset + 2] & 0xff) << 16;

    63                   // fall through

    64               case 2:

    65                   k1 ^= (data[offset + 1] & 0xff) << 8;

    66                   // fall through

    67               case 1:

    68                   k1 ^= (data[offset] & 0xff);

    69                   // fall through

    70               default:

    71                   k1 *= 0xcc9e2d51;

    72                   k1 = Integer.rotateLeft((int)k1, 15);

    73                   k1 *= 0x1b873593;

    74                   k1 &= 0xFFFFFFFFL;

    75                   h1 ^= k1;

    76                   h1 &= 0xFFFFFFFFL;

    77           }

    78       }

    79 

    80       // finalization

    81       h1 ^= len;

    82 

    83       // finalization mix force all bits of a hash block to avalanche

    84       h1 ^= h1 >> 16;

    85       h1 *= 0x85ebca6b;

    86       h1 &= 0xFFFFFFFFL;

    87       h1 ^= h1 >> 13;

    88       h1 *= 0xc2b2ae35;

    89       h1 &= 0xFFFFFFFFL;

    90       h1 ^= h1 >> 16;

    91 

    92       return h1 & 0xFFFFFFFFL;

    93   }

    94 }