GlueGen: src/java/com/jogamp/common/util/HashUtil.java Source File

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HashUtil.java
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1/**
2 * Copyright 2013 JogAmp Community. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without modification, are
5 * permitted provided that the following conditions are met:
6 *
7 * 1. Redistributions of source code must retain the above copyright notice, this list of
8 * conditions and the following disclaimer.
9 *
10 * 2. Redistributions in binary form must reproduce the above copyright notice, this list
11 * of conditions and the following disclaimer in the documentation and/or other materials
12 * provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
15 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
16 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
19 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
21 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
22 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 *
24 * The views and conclusions contained in the software and documentation are those of the
25 * authors and should not be interpreted as representing official policies, either expressed
26 * or implied, of JogAmp Community.
27 */
28package com.jogamp.common.util;
29
30 public class HashUtil {
31 /**
32 * Generates a 32bit equally distributed identity hash value
33 * from <code>addr</code> avoiding XOR collision.
34 */
35 public static int getAddrHash32_EqualDist(final long addr) {
36 // avoid xor collisions of low/high parts
37 // 31 * x == (x << 5) - x
38 final int hash = 31 + (int) addr ; // lo addr
39 return ((hash << 5) - hash) + (int) ( addr >>> 32 ) ; // hi addr
40 }
41
42 /**
43 * Generates a 32bit equally distributed identity hash value
44 * from <code>addr</code> and <code>size</code> avoiding XOR collision.
45 */
46 public static int getAddrSizeHash32_EqualDist(final long addr, final long size) {
47 // avoid xor collisions of low/high parts
48 // 31 * x == (x << 5) - x
49 int hash = 31 + (int) addr ; // lo addr
50 hash = ((hash << 5) - hash) + (int) ( addr >>> 32 ) ; // hi addr
51 hash = ((hash << 5) - hash) + (int) size ; // lo size
52 return ((hash << 5) - hash) + (int) ( size >>> 32 ) ; // hi size
53 }
54
55 /**
56 * Generates a 64bit equally distributed hash value
57 * from <code>addr</code> and <code>size</code> avoiding XOR collisions.
58 */
59 public static long getHash64(final long addr, final long size) {
60 // 31 * x == (x << 5) - x
61 final long hash = 31 + addr;
62 return ((hash << 5) - hash) + size;
63 }
64
65
66}
com.jogamp.common.util.HashUtil
Definition: HashUtil.java:30
com.jogamp.common.util.HashUtil.getHash64
static long getHash64(final long addr, final long size)
Generates a 64bit equally distributed hash value from addr and size avoiding XOR collisions.
Definition: HashUtil.java:59
com.jogamp.common.util.HashUtil.getAddrSizeHash32_EqualDist
static int getAddrSizeHash32_EqualDist(final long addr, final long size)
Generates a 32bit equally distributed identity hash value from addr and size avoiding XOR collision.
Definition: HashUtil.java:46
com.jogamp.common.util.HashUtil.getAddrHash32_EqualDist
static int getAddrHash32_EqualDist(final long addr)
Generates a 32bit equally distributed identity hash value from addr avoiding XOR collision.
Definition: HashUtil.java:35