/** * Copyright 2013 JogAmp Community. All rights reserved. * * Redistribution and use in source and binary forms, with or without modification, are * permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, this list of * conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright notice, this list * of conditions and the following disclaimer in the documentation and/or other materials * provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * The views and conclusions contained in the software and documentation are those of the * authors and should not be interpreted as representing official policies, either expressed * or implied, of JogAmp Community. */ package com.jogamp.common.util; public class HashUtil { /** * Generates a 32bit equally distributed identity hash value * from <code>addr</code> avoiding XOR collision. */ public static int getAddrHash32_EqualDist(long addr) { // avoid xor collisions of low/high parts // 31 * x == (x << 5) - x int hash = 31 + (int) addr ; // lo addr return ((hash << 5) - hash) + (int) ( addr >>> 32 ) ; // hi addr } /** * Generates a 32bit equally distributed identity hash value * from <code>addr</code> and <code>size</code> avoiding XOR collision. */ public static int getAddrSizeHash32_EqualDist(long addr, long size) { // avoid xor collisions of low/high parts // 31 * x == (x << 5) - x int hash = 31 + (int) addr ; // lo addr hash = ((hash << 5) - hash) + (int) ( addr >>> 32 ) ; // hi addr hash = ((hash << 5) - hash) + (int) size ; // lo size return ((hash << 5) - hash) + (int) ( size >>> 32 ) ; // hi size } /** * Generates a 64bit equally distributed hash value * from <code>addr</code> and <code>size</code> avoiding XOR collisions. */ public static long getHash64(long addr, long size) { // 31 * x == (x << 5) - x final long hash = 31 + addr; return ((hash << 5) - hash) + size; } }