Added MurmurHash3 algorithm
melvin
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/*
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* JBoss, Home of Professional Open Source
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* Copyright 2011 Red Hat Inc. and/or its affiliates and other
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* contributors as indicated by the @author tags. All rights reserved.
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* See the copyright.txt in the distribution for a full listing of
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* individual contributors.
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*
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* This is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This software is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this software; if not, write to the Free
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* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
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*/
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package magic;
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/**
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* MurmurHash3 implementation in Java, based on Austin Appleby's <a href=
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* "https://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp"
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* >original in C</a>
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*
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* Only implementing x64 version, because this should always be faster on 64 bit
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* native processors, even 64 bit being ran with a 32 bit OS; this should also
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* be as fast or faster than the x86 version on some modern 32 bit processors.
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*
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* @author Patrick McFarland
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* @see <a href="http://sites.google.com/site/murmurhash/">MurmurHash website</a>
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* @see <a href="http://en.wikipedia.org/wiki/MurmurHash">MurmurHash entry on Wikipedia</a>
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* @since 5.0
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*/
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public class MurmurHash3 {
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static class State {
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long h1;
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long h2;
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long k1;
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long k2;
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long c1;
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long c2;
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}
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static long getblock(byte[] key, int i) {
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return
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(((long) key[i + 0] & 0x00000000000000FFL) << 0)
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| (((long) key[i + 1] & 0x00000000000000FFL) << 8)
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| (((long) key[i + 2] & 0x00000000000000FFL) << 16)
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| (((long) key[i + 3] & 0x00000000000000FFL) << 24)
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| (((long) key[i + 4] & 0x00000000000000FFL) << 32)
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| (((long) key[i + 5] & 0x00000000000000FFL) << 40)
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| (((long) key[i + 6] & 0x00000000000000FFL) << 48)
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| (((long) key[i + 7] & 0x00000000000000FFL) << 56);
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}
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static void bmix(State state) {
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state.k1 *= state.c1;
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state.k1 = (state.k1 << 23) | (state.k1 >>> 64 - 23);
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state.k1 *= state.c2;
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state.h1 ^= state.k1;
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state.h1 += state.h2;
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state.h2 = (state.h2 << 41) | (state.h2 >>> 64 - 41);
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state.k2 *= state.c2;
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state.k2 = (state.k2 << 23) | (state.k2 >>> 64 - 23);
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state.k2 *= state.c1;
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state.h2 ^= state.k2;
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state.h2 += state.h1;
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state.h1 = state.h1 * 3 + 0x52dce729;
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state.h2 = state.h2 * 3 + 0x38495ab5;
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state.c1 = state.c1 * 5 + 0x7b7d159c;
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state.c2 = state.c2 * 5 + 0x6bce6396;
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}
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static long fmix(long k) {
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k ^= k >>> 33;
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k *= 0xff51afd7ed558ccdL;
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k ^= k >>> 33;
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k *= 0xc4ceb9fe1a85ec53L;
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k ^= k >>> 33;
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return k;
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}
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/**
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* Hash a value using the x64 128 bit variant of MurmurHash3
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*
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* @param key value to hash
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* @param seed random value
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* @return 128 bit hashed key, in an array containing two longs
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*/
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public static long[] MurmurHash3_x64_128(final byte[] key, final int seed) {
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State state = new State();
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state.h1 = 0x9368e53c2f6af274L ^ seed;
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state.h2 = 0x586dcd208f7cd3fdL ^ seed;
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state.c1 = 0x87c37b91114253d5L;
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state.c2 = 0x4cf5ad432745937fL;
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for (int i = 0; i < key.length / 16; i++) {
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state.k1 = getblock(key, i * 2 * 8);
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state.k2 = getblock(key, (i * 2 + 1) * 8);
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bmix(state);
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}
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state.k1 = 0;
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state.k2 = 0;
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int tail = (key.length >>> 4) << 4;
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switch (key.length & 15) {
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case 15: state.k2 ^= (long) key[tail + 14] << 48;
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case 14: state.k2 ^= (long) key[tail + 13] << 40;
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case 13: state.k2 ^= (long) key[tail + 12] << 32;
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case 12: state.k2 ^= (long) key[tail + 11] << 24;
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case 11: state.k2 ^= (long) key[tail + 10] << 16;
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case 10: state.k2 ^= (long) key[tail + 9] << 8;
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case 9: state.k2 ^= (long) key[tail + 8] << 0;
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case 8: state.k1 ^= (long) key[tail + 7] << 56;
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case 7: state.k1 ^= (long) key[tail + 6] << 48;
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case 6: state.k1 ^= (long) key[tail + 5] << 40;
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case 5: state.k1 ^= (long) key[tail + 4] << 32;
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case 4: state.k1 ^= (long) key[tail + 3] << 24;
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case 3: state.k1 ^= (long) key[tail + 2] << 16;
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case 2: state.k1 ^= (long) key[tail + 1] << 8;
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case 1: state.k1 ^= (long) key[tail + 0] << 0;
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bmix(state);
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}
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state.h2 ^= key.length;
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state.h1 += state.h2;
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state.h2 += state.h1;
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state.h1 = fmix(state.h1);
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state.h2 = fmix(state.h2);
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state.h1 += state.h2;
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state.h2 += state.h1;
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return new long[] { state.h1, state.h2 };
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}
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/**
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* Hash a value using the x64 64 bit variant of MurmurHash3
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*
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* @param key value to hash
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* @param seed random value
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* @return 64 bit hashed key
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*/
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public static long MurmurHash3_x64_64(final byte[] key, final int seed) {
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return MurmurHash3_x64_128(key, seed)[0];
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}
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/**
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* Hash a value using the x64 32 bit variant of MurmurHash3
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*
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* @param key value to hash
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* @param seed random value
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* @return 32 bit hashed key
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*/
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public static int MurmurHash3_x64_32(final byte[] key, final int seed) {
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return (int) (MurmurHash3_x64_128(key, seed)[0] >>> 32);
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}
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/**
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* Hash a value using the x64 128 bit variant of MurmurHash3
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*
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* @param key value to hash
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* @param seed random value
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* @return 128 bit hashed key, in an array containing two longs
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*/
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public static long[] MurmurHash3_x64_128(final long[] key, final int seed) {
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State state = new State();
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state.h1 = 0x9368e53c2f6af274L ^ seed;
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state.h2 = 0x586dcd208f7cd3fdL ^ seed;
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state.c1 = 0x87c37b91114253d5L;
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state.c2 = 0x4cf5ad432745937fL;
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for (int i = 0; i < key.length / 2; i++) {
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state.k1 = key[i * 2];
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state.k2 = key[i * 2 + 1];
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bmix(state);
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}
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long tail = key[key.length - 1];
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if (key.length % 2 != 0) {
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state.k1 ^= tail;
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bmix(state);
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}
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state.h2 ^= key.length * 8;
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state.h1 += state.h2;
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state.h2 += state.h1;
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state.h1 = fmix(state.h1);
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state.h2 = fmix(state.h2);
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state.h1 += state.h2;
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state.h2 += state.h1;
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return new long[] { state.h1, state.h2 };
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}
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/**
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* Hash a value using the x64 64 bit variant of MurmurHash3
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*
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* @param key value to hash
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* @param seed random value
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* @return 64 bit hashed key
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*/
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public static long MurmurHash3_x64_64(final long[] key, final int seed) {
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return MurmurHash3_x64_128(key, seed)[0];
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}
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/**
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* Hash a value using the x64 32 bit variant of MurmurHash3
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*
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* @param key value to hash
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* @param seed random value
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* @return 32 bit hashed key
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*/
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public static int MurmurHash3_x64_32(final long[] key, final int seed) {
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return (int) (MurmurHash3_x64_128(key, seed)[0] >>> 32);
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}
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public static long hash(long[] payload) {
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return MurmurHash3_x64_64(payload, 9001);
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}
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}
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