Fix Long*HashMap impl. of IntIntHashMap: Better 64bit hash value, using new HashUtil.

Introduce markup: /*keyHash*/(.*)/*keyHash*/ allowing Long*HashMap to inject hash function for 64bit value.

1 files changed, 66 insertions, 0 deletions

diff --git a/src/java/com/jogamp/common/util/HashUtil.java b/src/java/com/jogamp/common/util/HashUtil.java
new file mode 100644
index 0000000..c5a3bff
--- /dev/null
+++ b/src/java/com/jogamp/common/util/HashUtil.java
@@ -0,0 +1,66 @@
+/**
+ * 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;
+    }
+
+    
+}