com.spikeify.MurmurHash3 Maven / Gradle / Ivy
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package com.spikeify;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
/**
* An incremental hasher implementing Murmur3 hash function
*
* From: https://code.google.com/p/cumulusrdf/source/browse/trunk/src/edu/kit/aifb/cumulus/store/MurmurHash3.java?r=122
*/
public class MurmurHash3 {
private final long SEED;
private final State state;
private int keyLen;
private byte[] key = new byte[16]; // buffer
public MurmurHash3(long seed) {
this.SEED = seed;
state = new State();
state.h1 = 0x9368e53c2f6af274L ^ SEED;
state.h2 = 0x586dcd208f7cd3fdL ^ SEED;
state.c1 = 0x87c37b91114253d5L;
state.c2 = 0x4cf5ad432745937fL;
}
public MurmurHash3() {
this(0);
}
static class State {
long h1;
long h2;
long k1;
long k2;
long c1;
long c2;
}
public MurmurHash3 add(final short data) {
add((byte) (data & 0x00FF));
add((byte) ((data & 0xFF00) << 8));
return this;
}
public MurmurHash3 add(final long data) {
byte[] bytes = new byte[]{
(byte) (data >> 56),
(byte) (data >> 48),
(byte) (data >> 40),
(byte) (data >> 32),
(byte) (data >> 24),
(byte) (data >> 16),
(byte) (data >> 8),
(byte) data
};
add(bytes);
return this;
}
public synchronized MurmurHash3 add(byte byteData) {
key[keyLen++ % 16] = byteData;
if (keyLen % 16 == 0) {
state.k1 = getblock(0);
state.k2 = getblock(8);
bmix(state);
}
return this;
}
public synchronized MurmurHash3 add(byte[] byteArray) {
for (byte byteData : byteArray) {
key[keyLen++ % 16] = byteData;
if (keyLen % 16 == 0) {
state.k1 = getblock(0);
state.k2 = getblock(8);
bmix(state);
}
}
return this;
}
public long[] hash() {
state.k1 = 0;
state.k2 = 0;
// int tail = (keyLen >>> 4) << 4;
int tail = 0;
switch (keyLen & 15) {
case 15:
state.k2 ^= (long) key[tail + 14] << 48;
case 14:
state.k2 ^= (long) key[tail + 13] << 40;
case 13:
state.k2 ^= (long) key[tail + 12] << 32;
case 12:
state.k2 ^= (long) key[tail + 11] << 24;
case 11:
state.k2 ^= (long) key[tail + 10] << 16;
case 10:
state.k2 ^= (long) key[tail + 9] << 8;
case 9:
state.k2 ^= (long) key[tail + 8];
case 8:
state.k1 ^= (long) key[tail + 7] << 56;
case 7:
state.k1 ^= (long) key[tail + 6] << 48;
case 6:
state.k1 ^= (long) key[tail + 5] << 40;
case 5:
state.k1 ^= (long) key[tail + 4] << 32;
case 4:
state.k1 ^= (long) key[tail + 3] << 24;
case 3:
state.k1 ^= (long) key[tail + 2] << 16;
case 2:
state.k1 ^= (long) key[tail + 1] << 8;
case 1:
state.k1 ^= (long) key[tail];
bmix(state);
}
state.h2 ^= keyLen;
state.h1 += state.h2;
state.h2 += state.h1;
state.h1 = fmix(state.h1);
state.h2 = fmix(state.h2);
state.h1 += state.h2;
state.h2 += state.h1;
return new long[]{state.h1, state.h2};
}
private static void bmix(State state) {
state.k1 *= state.c1;
state.k1 = (state.k1 << 23) | (state.k1 >>> 64 - 23);
state.k1 *= state.c2;
state.h1 ^= state.k1;
state.h1 += state.h2;
state.h2 = (state.h2 << 41) | (state.h2 >>> 64 - 41);
state.k2 *= state.c2;
state.k2 = (state.k2 << 23) | (state.k2 >>> 64 - 23);
state.k2 *= state.c1;
state.h2 ^= state.k2;
state.h2 += state.h1;
state.h1 = state.h1 * 3 + 0x52dce729;
state.h2 = state.h2 * 3 + 0x38495ab5;
state.c1 = state.c1 * 5 + 0x7b7d159c;
state.c2 = state.c2 * 5 + 0x6bce6396;
}
private static long fmix(long k) {
k ^= k >>> 33;
k *= 0xff51afd7ed558ccdL;
k ^= k >>> 33;
k *= 0xc4ceb9fe1a85ec53L;
k ^= k >>> 33;
return k;
}
private long getblock(int i) {
return
(((long) key[i] & 0x00000000000000FFL))
| (((long) key[i + 1] & 0x00000000000000FFL) << 8)
| (((long) key[i + 2] & 0x00000000000000FFL) << 16)
| (((long) key[i + 3] & 0x00000000000000FFL) << 24)
| (((long) key[i + 4] & 0x00000000000000FFL) << 32)
| (((long) key[i + 5] & 0x00000000000000FFL) << 40)
| (((long) key[i + 6] & 0x00000000000000FFL) << 48)
| (((long) key[i + 7] & 0x00000000000000FFL) << 56);
}
}