Java tutorial
/* * 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. */ package org.apache.bookkeeper.common.hash; import io.netty.buffer.ByteBuf; /** * Murmur3 is successor to Murmur2 fast non-crytographic hash algorithms. * * Murmur3 32 and 128 bit variants. * 32-bit Java port of https://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp#94 * 128-bit Java port of https://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp#255 * * This is a public domain code with no copyrights. * From homepage of MurmurHash (https://code.google.com/p/smhasher/), * "All MurmurHash versions are public domain software, and the author disclaims all copyright * to their code." */ public class Murmur3 { // Constants for 32 bit variant private static final int C1_32 = 0xcc9e2d51; private static final int C2_32 = 0x1b873593; private static final int R1_32 = 15; private static final int R2_32 = 13; private static final int M_32 = 5; private static final int N_32 = 0xe6546b64; // Constants for 128 bit variant private static final long C1 = 0x87c37b91114253d5L; private static final long C2 = 0x4cf5ad432745937fL; private static final int R1 = 31; private static final int R2 = 27; private static final int R3 = 33; private static final int M = 5; private static final int N1 = 0x52dce729; private static final int N2 = 0x38495ab5; public static final int DEFAULT_SEED = 104729; /** * Murmur3 32-bit variant. * * @param data - input byte array * @return - hashcode */ public static int hash32(byte[] data) { return hash32(data, 0, data.length, DEFAULT_SEED); } /** * Murmur3 32-bit variant. * * @param data - input byte array * @param length - length of array * @return - hashcode */ public static int hash32(byte[] data, int length) { return hash32(data, 0, length, DEFAULT_SEED); } /** * Murmur3 32-bit variant. * * @param data - input byte array * @param length - length of array * @param seed - seed. (default 0) * @return - hashcode */ public static int hash32(byte[] data, int length, int seed) { return hash32(data, 0, length, seed); } /** * Murmur3 32-bit variant. * * @param data - input byte array * @param offset - offset of data * @param length - length of array * @param seed - seed. (default 0) * @return - hashcode */ public static int hash32(byte[] data, int offset, int length, int seed) { int hash = seed; final int nblocks = length >> 2; // body for (int i = 0; i < nblocks; i++) { int i_4 = i << 2; int k = (data[offset + i_4] & 0xff) | ((data[offset + i_4 + 1] & 0xff) << 8) | ((data[offset + i_4 + 2] & 0xff) << 16) | ((data[offset + i_4 + 3] & 0xff) << 24); // mix functions k *= C1_32; k = Integer.rotateLeft(k, R1_32); k *= C2_32; hash ^= k; hash = Integer.rotateLeft(hash, R2_32) * M_32 + N_32; } // tail int idx = nblocks << 2; int k1 = 0; switch (length - idx) { case 3: k1 ^= data[offset + idx + 2] << 16; case 2: k1 ^= data[offset + idx + 1] << 8; case 1: k1 ^= data[offset + idx]; // mix functions k1 *= C1_32; k1 = Integer.rotateLeft(k1, R1_32); k1 *= C2_32; hash ^= k1; } // finalization hash ^= length; hash ^= (hash >>> 16); hash *= 0x85ebca6b; hash ^= (hash >>> 13); hash *= 0xc2b2ae35; hash ^= (hash >>> 16); return hash; } public static int hash32(ByteBuf data, int offset, int length, int seed) { int hash = seed; final int nblocks = length >> 2; // body for (int i = 0; i < nblocks; i++) { int i_4 = i << 2; int k = (data.getByte(offset + i_4) & 0xff) | ((data.getByte(offset + i_4 + 1) & 0xff) << 8) | ((data.getByte(offset + i_4 + 2) & 0xff) << 16) | ((data.getByte(offset + i_4 + 3) & 0xff) << 24); // mix functions k *= C1_32; k = Integer.rotateLeft(k, R1_32); k *= C2_32; hash ^= k; hash = Integer.rotateLeft(hash, R2_32) * M_32 + N_32; } // tail int idx = nblocks << 2; int k1 = 0; switch (length - idx) { case 3: k1 ^= data.getByte(offset + idx + 2) << 16; case 2: k1 ^= data.getByte(offset + idx + 1) << 8; case 1: k1 ^= data.getByte(offset + idx); // mix functions k1 *= C1_32; k1 = Integer.rotateLeft(k1, R1_32); k1 *= C2_32; hash ^= k1; } // finalization hash ^= length; hash ^= (hash >>> 16); hash *= 0x85ebca6b; hash ^= (hash >>> 13); hash *= 0xc2b2ae35; hash ^= (hash >>> 16); return hash; } /** * Murmur3 128-bit variant. * * @param data - input byte array * @return - hashcode (2 longs) */ public static long[] hash128(byte[] data) { return hash128(data, 0, data.length, DEFAULT_SEED); } /** * Murmur3 128-bit variant. * * @param data - input byte array * @param offset - the first element of array * @param length - length of array * @param seed - seed. (default is 0) * @return - hashcode (2 longs) */ public static long[] hash128(byte[] data, int offset, int length, long seed) { long h1 = seed; long h2 = seed; final int nblocks = length >> 4; // body for (int i = 0; i < nblocks; i++) { final int i16 = i << 4; long k1 = ((long) data[offset + i16] & 0xff) | (((long) data[offset + i16 + 1] & 0xff) << 8) | (((long) data[offset + i16 + 2] & 0xff) << 16) | (((long) data[offset + i16 + 3] & 0xff) << 24) | (((long) data[offset + i16 + 4] & 0xff) << 32) | (((long) data[offset + i16 + 5] & 0xff) << 40) | (((long) data[offset + i16 + 6] & 0xff) << 48) | (((long) data[offset + i16 + 7] & 0xff) << 56); long k2 = ((long) data[offset + i16 + 8] & 0xff) | (((long) data[offset + i16 + 9] & 0xff) << 8) | (((long) data[offset + i16 + 10] & 0xff) << 16) | (((long) data[offset + i16 + 11] & 0xff) << 24) | (((long) data[offset + i16 + 12] & 0xff) << 32) | (((long) data[offset + i16 + 13] & 0xff) << 40) | (((long) data[offset + i16 + 14] & 0xff) << 48) | (((long) data[offset + i16 + 15] & 0xff) << 56); // mix functions for k1 k1 *= C1; k1 = Long.rotateLeft(k1, R1); k1 *= C2; h1 ^= k1; h1 = Long.rotateLeft(h1, R2); h1 += h2; h1 = h1 * M + N1; // mix functions for k2 k2 *= C2; k2 = Long.rotateLeft(k2, R3); k2 *= C1; h2 ^= k2; h2 = Long.rotateLeft(h2, R1); h2 += h1; h2 = h2 * M + N2; } // tail long k1 = 0; long k2 = 0; int tailStart = nblocks << 4; switch (length - tailStart) { case 15: k2 ^= (long) (data[offset + tailStart + 14] & 0xff) << 48; case 14: k2 ^= (long) (data[offset + tailStart + 13] & 0xff) << 40; case 13: k2 ^= (long) (data[offset + tailStart + 12] & 0xff) << 32; case 12: k2 ^= (long) (data[offset + tailStart + 11] & 0xff) << 24; case 11: k2 ^= (long) (data[offset + tailStart + 10] & 0xff) << 16; case 10: k2 ^= (long) (data[offset + tailStart + 9] & 0xff) << 8; case 9: k2 ^= (long) (data[offset + tailStart + 8] & 0xff); k2 *= C2; k2 = Long.rotateLeft(k2, R3); k2 *= C1; h2 ^= k2; case 8: k1 ^= (long) (data[offset + tailStart + 7] & 0xff) << 56; case 7: k1 ^= (long) (data[offset + tailStart + 6] & 0xff) << 48; case 6: k1 ^= (long) (data[offset + tailStart + 5] & 0xff) << 40; case 5: k1 ^= (long) (data[offset + tailStart + 4] & 0xff) << 32; case 4: k1 ^= (long) (data[offset + tailStart + 3] & 0xff) << 24; case 3: k1 ^= (long) (data[offset + tailStart + 2] & 0xff) << 16; case 2: k1 ^= (long) (data[offset + tailStart + 1] & 0xff) << 8; case 1: k1 ^= (long) (data[offset + tailStart] & 0xff); k1 *= C1; k1 = Long.rotateLeft(k1, R1); k1 *= C2; h1 ^= k1; } // finalization h1 ^= length; h2 ^= length; h1 += h2; h2 += h1; h1 = fmix64(h1); h2 = fmix64(h2); h1 += h2; h2 += h1; return new long[] { h1, h2 }; } /** * Murmur3 128-bit variant. * * @param data - input byte array * @param offset - the first element of array * @param length - length of array * @param seed - seed. (default is 0) * @return - hashcode (2 longs) */ public static long[] hash128(ByteBuf data, int offset, int length, long seed) { long h1 = seed; long h2 = seed; final int nblocks = length >> 4; // body for (int i = 0; i < nblocks; i++) { final int i16 = i << 4; long k1 = ((long) data.getByte(offset + i16) & 0xff) | (((long) data.getByte(offset + i16 + 1) & 0xff) << 8) | (((long) data.getByte(offset + i16 + 2) & 0xff) << 16) | (((long) data.getByte(offset + i16 + 3) & 0xff) << 24) | (((long) data.getByte(offset + i16 + 4) & 0xff) << 32) | (((long) data.getByte(offset + i16 + 5) & 0xff) << 40) | (((long) data.getByte(offset + i16 + 6) & 0xff) << 48) | (((long) data.getByte(offset + i16 + 7) & 0xff) << 56); long k2 = ((long) data.getByte(offset + i16 + 8) & 0xff) | (((long) data.getByte(offset + i16 + 9) & 0xff) << 8) | (((long) data.getByte(offset + i16 + 10) & 0xff) << 16) | (((long) data.getByte(offset + i16 + 11) & 0xff) << 24) | (((long) data.getByte(offset + i16 + 12) & 0xff) << 32) | (((long) data.getByte(offset + i16 + 13) & 0xff) << 40) | (((long) data.getByte(offset + i16 + 14) & 0xff) << 48) | (((long) data.getByte(offset + i16 + 15) & 0xff) << 56); // mix functions for k1 k1 *= C1; k1 = Long.rotateLeft(k1, R1); k1 *= C2; h1 ^= k1; h1 = Long.rotateLeft(h1, R2); h1 += h2; h1 = h1 * M + N1; // mix functions for k2 k2 *= C2; k2 = Long.rotateLeft(k2, R3); k2 *= C1; h2 ^= k2; h2 = Long.rotateLeft(h2, R1); h2 += h1; h2 = h2 * M + N2; } // tail long k1 = 0; long k2 = 0; int tailStart = nblocks << 4; switch (length - tailStart) { case 15: k2 ^= (long) (data.getByte(offset + tailStart + 14) & 0xff) << 48; case 14: k2 ^= (long) (data.getByte(offset + tailStart + 13) & 0xff) << 40; case 13: k2 ^= (long) (data.getByte(offset + tailStart + 12) & 0xff) << 32; case 12: k2 ^= (long) (data.getByte(offset + tailStart + 11) & 0xff) << 24; case 11: k2 ^= (long) (data.getByte(offset + tailStart + 10) & 0xff) << 16; case 10: k2 ^= (long) (data.getByte(offset + tailStart + 9) & 0xff) << 8; case 9: k2 ^= (long) (data.getByte(offset + tailStart + 8) & 0xff); k2 *= C2; k2 = Long.rotateLeft(k2, R3); k2 *= C1; h2 ^= k2; case 8: k1 ^= (long) (data.getByte(offset + tailStart + 7) & 0xff) << 56; case 7: k1 ^= (long) (data.getByte(offset + tailStart + 6) & 0xff) << 48; case 6: k1 ^= (long) (data.getByte(offset + tailStart + 5) & 0xff) << 40; case 5: k1 ^= (long) (data.getByte(offset + tailStart + 4) & 0xff) << 32; case 4: k1 ^= (long) (data.getByte(offset + tailStart + 3) & 0xff) << 24; case 3: k1 ^= (long) (data.getByte(offset + tailStart + 2) & 0xff) << 16; case 2: k1 ^= (long) (data.getByte(offset + tailStart + 1) & 0xff) << 8; case 1: k1 ^= (long) (data.getByte(offset + tailStart) & 0xff); k1 *= C1; k1 = Long.rotateLeft(k1, R1); k1 *= C2; h1 ^= k1; } // finalization h1 ^= length; h2 ^= length; h1 += h2; h2 += h1; h1 = fmix64(h1); h2 = fmix64(h2); h1 += h2; h2 += h1; return new long[] { h1, h2 }; } private static long fmix64(long h) { h ^= (h >>> 33); h *= 0xff51afd7ed558ccdL; h ^= (h >>> 33); h *= 0xc4ceb9fe1a85ec53L; h ^= (h >>> 33); return h; } }