| /* |
| * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package sun.misc; |
| |
| import java.util.concurrent.ThreadLocalRandom; |
| // ----- BEGIN android ----- |
| import java.lang.JavaLangAccess; |
| // ----- END android ----- |
| |
| /** |
| * Hashing utilities. |
| * |
| * Little endian implementations of Murmur3 hashing. |
| */ |
| public class Hashing { |
| |
| /** |
| * Static utility methods only. |
| */ |
| private Hashing() { |
| throw new Error("No instances"); |
| } |
| |
| public static int murmur3_32(byte[] data) { |
| return murmur3_32(0, data, 0, data.length); |
| } |
| |
| public static int murmur3_32(int seed, byte[] data) { |
| return murmur3_32(seed, data, 0, data.length); |
| } |
| |
| @SuppressWarnings("fallthrough") |
| public static int murmur3_32(int seed, byte[] data, int offset, int len) { |
| int h1 = seed; |
| int count = len; |
| |
| // body |
| while (count >= 4) { |
| int k1 = (data[offset] & 0x0FF) |
| | (data[offset + 1] & 0x0FF) << 8 |
| | (data[offset + 2] & 0x0FF) << 16 |
| | data[offset + 3] << 24; |
| |
| count -= 4; |
| offset += 4; |
| |
| k1 *= 0xcc9e2d51; |
| k1 = Integer.rotateLeft(k1, 15); |
| k1 *= 0x1b873593; |
| |
| h1 ^= k1; |
| h1 = Integer.rotateLeft(h1, 13); |
| h1 = h1 * 5 + 0xe6546b64; |
| } |
| |
| // tail |
| |
| if (count > 0) { |
| int k1 = 0; |
| |
| switch (count) { |
| case 3: |
| k1 ^= (data[offset + 2] & 0xff) << 16; |
| // fall through |
| case 2: |
| k1 ^= (data[offset + 1] & 0xff) << 8; |
| // fall through |
| case 1: |
| k1 ^= (data[offset] & 0xff); |
| // fall through |
| default: |
| k1 *= 0xcc9e2d51; |
| k1 = Integer.rotateLeft(k1, 15); |
| k1 *= 0x1b873593; |
| h1 ^= k1; |
| } |
| } |
| |
| // finalization |
| |
| h1 ^= len; |
| |
| // finalization mix force all bits of a hash block to avalanche |
| h1 ^= h1 >>> 16; |
| h1 *= 0x85ebca6b; |
| h1 ^= h1 >>> 13; |
| h1 *= 0xc2b2ae35; |
| h1 ^= h1 >>> 16; |
| |
| return h1; |
| } |
| |
| public static int murmur3_32(char[] data) { |
| return murmur3_32(0, data, 0, data.length); |
| } |
| |
| public static int murmur3_32(int seed, char[] data) { |
| return murmur3_32(seed, data, 0, data.length); |
| } |
| |
| public static int murmur3_32(int seed, char[] data, int offset, int len) { |
| int h1 = seed; |
| |
| int off = offset; |
| int count = len; |
| |
| // body |
| while (count >= 2) { |
| int k1 = (data[off++] & 0xFFFF) | (data[off++] << 16); |
| |
| count -= 2; |
| |
| k1 *= 0xcc9e2d51; |
| k1 = Integer.rotateLeft(k1, 15); |
| k1 *= 0x1b873593; |
| |
| h1 ^= k1; |
| h1 = Integer.rotateLeft(h1, 13); |
| h1 = h1 * 5 + 0xe6546b64; |
| } |
| |
| // tail |
| |
| if (count > 0) { |
| int k1 = data[off]; |
| |
| k1 *= 0xcc9e2d51; |
| k1 = Integer.rotateLeft(k1, 15); |
| k1 *= 0x1b873593; |
| h1 ^= k1; |
| } |
| |
| // finalization |
| |
| h1 ^= len * (Character.SIZE / Byte.SIZE); |
| |
| // finalization mix force all bits of a hash block to avalanche |
| h1 ^= h1 >>> 16; |
| h1 *= 0x85ebca6b; |
| h1 ^= h1 >>> 13; |
| h1 *= 0xc2b2ae35; |
| h1 ^= h1 >>> 16; |
| |
| return h1; |
| } |
| |
| public static int murmur3_32(int[] data) { |
| return murmur3_32(0, data, 0, data.length); |
| } |
| |
| public static int murmur3_32(int seed, int[] data) { |
| return murmur3_32(seed, data, 0, data.length); |
| } |
| |
| public static int murmur3_32(int seed, int[] data, int offset, int len) { |
| int h1 = seed; |
| |
| int off = offset; |
| int end = offset + len; |
| |
| // body |
| while (off < end) { |
| int k1 = data[off++]; |
| |
| k1 *= 0xcc9e2d51; |
| k1 = Integer.rotateLeft(k1, 15); |
| k1 *= 0x1b873593; |
| |
| h1 ^= k1; |
| h1 = Integer.rotateLeft(h1, 13); |
| h1 = h1 * 5 + 0xe6546b64; |
| } |
| |
| // tail (always empty, as body is always 32-bit chunks) |
| |
| // finalization |
| |
| h1 ^= len * (Integer.SIZE / Byte.SIZE); |
| |
| // finalization mix force all bits of a hash block to avalanche |
| h1 ^= h1 >>> 16; |
| h1 *= 0x85ebca6b; |
| h1 ^= h1 >>> 13; |
| h1 *= 0xc2b2ae35; |
| h1 ^= h1 >>> 16; |
| |
| return h1; |
| } |
| |
| /** |
| * Return a 32 bit hash value for the specified string. The algorithm is |
| * unspecified but will be consistent within a VM instance. |
| * |
| * @param string String to be hashed. |
| * @return hash value of the string. |
| */ |
| public static int stringHash32(String string) { |
| // Android-changed: Access JavaLangAccess directly. |
| return JavaLangAccess.getStringHash32(string); |
| } |
| |
| /** |
| * Return a non-zero 32-bit pseudo random value. The {@code instance} object |
| * may be used as part of the value. |
| * |
| * @param instance an object to use if desired in choosing value. |
| * @return a non-zero 32-bit pseudo random value. |
| */ |
| public static int randomHashSeed(Object instance) { |
| int seed; |
| if (sun.misc.VM.isBooted()) { |
| seed = ThreadLocalRandom.current().nextInt(); |
| } else { |
| // lower quality "random" seed value--still better than zero and not |
| // not practically reversible. |
| int hashing_seed[] = { |
| System.identityHashCode(Hashing.class), |
| System.identityHashCode(instance), |
| System.identityHashCode(Thread.currentThread()), |
| (int) Thread.currentThread().getId(), |
| (int) (System.currentTimeMillis() >>> 2), // resolution is poor |
| (int) (System.nanoTime() >>> 5), // resolution is poor |
| (int) (Runtime.getRuntime().freeMemory() >>> 4) // alloc min |
| }; |
| |
| seed = murmur3_32(hashing_seed); |
| } |
| |
| // force to non-zero. |
| return (0 != seed) ? seed : 1; |
| } |
| } |