/**
* Copyright 2016 LinkedIn Corp. All rights reserved.
*
* 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.
*/
package com.github.ambry.utils;
import java.nio.ByteBuffer;
/**
* This is a very fast, non-cryptographic hash suitable for general hash-based
* lookup. See http://murmurhash.googlepages.com/ for more details.
*
* hash32() and hash64() are MurmurHash 2.0.
* hash3_x64_128() is MurmurHash 3.0.
*
* <p>
* The C version of MurmurHash 2.0 found at that site was ported to Java by
* Andrzej Bialecki (ab at getopt org).
* </p>
*/
public class MurmurHash {
public static int hash32(ByteBuffer data, int offset, int length, int seed) {
int m = 0x5bd1e995;
int r = 24;
int h = seed ^ length;
int len_4 = length >> 2;
for (int i = 0; i < len_4; i++) {
int i_4 = i << 2;
int k = data.get(offset + i_4 + 3);
k = k << 8;
k = k | (data.get(offset + i_4 + 2) & 0xff);
k = k << 8;
k = k | (data.get(offset + i_4 + 1) & 0xff);
k = k << 8;
k = k | (data.get(offset + i_4 + 0) & 0xff);
k *= m;
k ^= k >>> r;
k *= m;
h *= m;
h ^= k;
}
// avoid calculating modulo
int len_m = len_4 << 2;
int left = length - len_m;
if (left != 0) {
if (left >= 3) {
h ^= (int) data.get(offset + length - 3) << 16;
}
if (left >= 2) {
h ^= (int) data.get(offset + length - 2) << 8;
}
if (left >= 1) {
h ^= (int) data.get(offset + length - 1);
}
h *= m;
}
h ^= h >>> 13;
h *= m;
h ^= h >>> 15;
return h;
}
public static long hash2_64(ByteBuffer key, int offset, int length, long seed) {
long m64 = 0xc6a4a7935bd1e995L;
int r64 = 47;
long h64 = (seed & 0xffffffffL) ^ (m64 * length);
int lenLongs = length >> 3;
for (int i = 0; i < lenLongs; ++i) {
int i_8 = i << 3;
long k64 = ((long) key.get(offset + i_8 + 0) & 0xff) + (((long) key.get(offset + i_8 + 1) & 0xff) << 8) + (
((long) key.get(offset + i_8 + 2) & 0xff) << 16) + (((long) key.get(offset + i_8 + 3) & 0xff) << 24) + (
((long) key.get(offset + i_8 + 4) & 0xff) << 32) + (((long) key.get(offset + i_8 + 5) & 0xff) << 40) + (
((long) key.get(offset + i_8 + 6) & 0xff) << 48) + (((long) key.get(offset + i_8 + 7) & 0xff) << 56);
k64 *= m64;
k64 ^= k64 >>> r64;
k64 *= m64;
h64 ^= k64;
h64 *= m64;
}
int rem = length & 0x7;
switch (rem) {
case 0:
break;
case 7:
h64 ^= (long) key.get(offset + length - rem + 6) << 48;
case 6:
h64 ^= (long) key.get(offset + length - rem + 5) << 40;
case 5:
h64 ^= (long) key.get(offset + length - rem + 4) << 32;
case 4:
h64 ^= (long) key.get(offset + length - rem + 3) << 24;
case 3:
h64 ^= (long) key.get(offset + length - rem + 2) << 16;
case 2:
h64 ^= (long) key.get(offset + length - rem + 1) << 8;
case 1:
h64 ^= (long) key.get(offset + length - rem);
h64 *= m64;
}
h64 ^= h64 >>> r64;
h64 *= m64;
h64 ^= h64 >>> r64;
return h64;
}
protected static long getblock(ByteBuffer key, int offset, int index) {
int i_8 = index << 3;
int blockOffset = offset + i_8;
return ((long) key.get(blockOffset + 0) & 0xff) + (((long) key.get(blockOffset + 1) & 0xff) << 8) + (
((long) key.get(blockOffset + 2) & 0xff) << 16) + (((long) key.get(blockOffset + 3) & 0xff) << 24) + (
((long) key.get(blockOffset + 4) & 0xff) << 32) + (((long) key.get(blockOffset + 5) & 0xff) << 40) + (
((long) key.get(blockOffset + 6) & 0xff) << 48) + (((long) key.get(blockOffset + 7) & 0xff) << 56);
}
protected static long rotl64(long v, int n) {
return ((v << n) | (v >>> (64 - n)));
}
protected static long fmix(long k) {
k ^= k >>> 33;
k *= 0xff51afd7ed558ccdL;
k ^= k >>> 33;
k *= 0xc4ceb9fe1a85ec53L;
k ^= k >>> 33;
return k;
}
public static long[] hash3_x64_128(ByteBuffer key, int offset, int length, long seed) {
final int nblocks = length >> 4; // Process as 128-bit blocks.
long h1 = seed;
long h2 = seed;
long c1 = 0x87c37b91114253d5L;
long c2 = 0x4cf5ad432745937fL;
//----------
// body
for (int i = 0; i < nblocks; i++) {
long k1 = getblock(key, offset, i * 2 + 0);
long k2 = getblock(key, offset, i * 2 + 1);
k1 *= c1;
k1 = rotl64(k1, 31);
k1 *= c2;
h1 ^= k1;
h1 = rotl64(h1, 27);
h1 += h2;
h1 = h1 * 5 + 0x52dce729;
k2 *= c2;
k2 = rotl64(k2, 33);
k2 *= c1;
h2 ^= k2;
h2 = rotl64(h2, 31);
h2 += h1;
h2 = h2 * 5 + 0x38495ab5;
}
//----------
// tail
// Advance offset to the unprocessed tail of the data.
offset += nblocks * 16;
long k1 = 0;
long k2 = 0;
switch (length & 15) {
case 15:
k2 ^= ((long) key.get(offset + 14)) << 48;
case 14:
k2 ^= ((long) key.get(offset + 13)) << 40;
case 13:
k2 ^= ((long) key.get(offset + 12)) << 32;
case 12:
k2 ^= ((long) key.get(offset + 11)) << 24;
case 11:
k2 ^= ((long) key.get(offset + 10)) << 16;
case 10:
k2 ^= ((long) key.get(offset + 9)) << 8;
case 9:
k2 ^= ((long) key.get(offset + 8)) << 0;
k2 *= c2;
k2 = rotl64(k2, 33);
k2 *= c1;
h2 ^= k2;
case 8:
k1 ^= ((long) key.get(offset + 7)) << 56;
case 7:
k1 ^= ((long) key.get(offset + 6)) << 48;
case 6:
k1 ^= ((long) key.get(offset + 5)) << 40;
case 5:
k1 ^= ((long) key.get(offset + 4)) << 32;
case 4:
k1 ^= ((long) key.get(offset + 3)) << 24;
case 3:
k1 ^= ((long) key.get(offset + 2)) << 16;
case 2:
k1 ^= ((long) key.get(offset + 1)) << 8;
case 1:
k1 ^= ((long) key.get(offset));
k1 *= c1;
k1 = rotl64(k1, 31);
k1 *= c2;
h1 ^= k1;
}
;
//----------
// finalization
h1 ^= length;
h2 ^= length;
h1 += h2;
h2 += h1;
h1 = fmix(h1);
h2 = fmix(h2);
h1 += h2;
h2 += h1;
return (new long[]{h1, h2});
}
}