[infinispan-commits] Infinispan SVN: r1753 - in trunk/core/src/main/java/org/infinispan/util: hash and 1 other directory.

[infinispan-commits at lists.jboss.org]

Author: manik.surtani at jboss.com
Date: 2010-05-07 05:24:19 -0400 (Fri, 07 May 2010)
New Revision: 1753

Added:
   trunk/core/src/main/java/org/infinispan/util/hash/
   trunk/core/src/main/java/org/infinispan/util/hash/MurmurHash2.java
Log:
Added MurmurHash2 impl

Added: trunk/core/src/main/java/org/infinispan/util/hash/MurmurHash2.java
===================================================================
--- trunk/core/src/main/java/org/infinispan/util/hash/MurmurHash2.java	                        (rev 0)
+++ trunk/core/src/main/java/org/infinispan/util/hash/MurmurHash2.java	2010-05-07 09:24:19 UTC (rev 1753)
@@ -0,0 +1,72 @@
+package org.infinispan.util.hash;
+
+import java.util.Random;
+
+/**
+ * TODO: Document this
+ *
+ * @author Manik Surtani
+ * @version 4.1
+ */
+public class MurmurHash2 {
+
+   public static final int hash(byte[] payload) {
+      int m = 0x5bd1e995;
+      int r = 24;
+      int h = new Random().nextInt() ^ 1024;
+
+      int len = payload.length;
+      int offset = 0;
+      while (len >= 4) {
+         int k = payload[offset];
+         k |= payload[offset + 1] << 8;
+         k |= payload[offset + 2] << 16;
+         k |= payload[offset + 3] << 24;
+
+         k *= m;
+         k ^= k >> r;
+         k *= m;
+         h *= m;
+         h ^= k;
+
+         len -= 4;
+         offset += 4;
+      }
+
+      switch (len) {
+         case 3:
+            h ^= payload[offset + 2] << 16;
+         case 2:
+            h ^= payload[offset + 1] << 8;
+         case 1:
+            h ^= payload[offset];
+            h *= m;
+      }
+
+      h ^= h >> 13;
+      h *= m;
+      h ^= h >> 15;
+
+      return h;
+   }
+
+   public static final int hash(int hashcode) {
+      byte[] b = new byte[4];
+      b[0] = (byte) hashcode;
+      b[1] = (byte) (hashcode >> 8);
+      b[2] = (byte) (hashcode >> 16);
+      b[3] = (byte) (hashcode >> 24);
+      return hash(b);
+   }
+
+   public static final int hash(Object o) {
+      if (o instanceof byte[])
+         return hash((byte[]) o);
+      else if (o instanceof String)
+         return hash(((String) o).getBytes());
+      else
+         return hash(o.hashCode());
+   }
+
+
+}


Property changes on: trunk/core/src/main/java/org/infinispan/util/hash/MurmurHash2.java
___________________________________________________________________
Name: svn:keywords
   + Id Revision
Name: svn:eol-style
   + LF