1 files changed, 48 insertions, 111 deletions

diff --git a/guava/src/com/google/common/hash/Murmur3_32HashFunction.java b/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
index c6637de..5c03b92 100644
--- a/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
+++ b/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
@@ -12,42 +12,23 @@
  * the License.
  */
 
-/*
- * MurmurHash3 was written by Austin Appleby, and is placed in the public
- * domain. The author hereby disclaims copyright to this source code.
- */
-
-/*
- * Source:
- * http://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp
- * (Modified to adapt to Guava coding conventions and to use the HashFunction interface)
- */
-
 package com.google.common.hash;
 
 import static com.google.common.primitives.UnsignedBytes.toInt;
 
-import com.google.common.primitives.Chars;
-import com.google.common.primitives.Ints;
-import com.google.common.primitives.Longs;
-
 import java.io.Serializable;
 import java.nio.ByteBuffer;
 
 /**
  * See http://smhasher.googlecode.com/svn/trunk/MurmurHash3.cpp
  * MurmurHash3_x86_32
- *
- * @author Austin Appleby
- * @author Dimitris Andreou
- * @author Kurt Alfred Kluever
+ * 
+ * @author aappleby@google.com (Austin Appleby)
+ * @author andreou@google.com (Dimitris Andreou)
  */
 final class Murmur3_32HashFunction extends AbstractStreamingHashFunction implements Serializable {
-  private static final int C1 = 0xcc9e2d51;
-  private static final int C2 = 0x1b873593;
-
   private final int seed;
-
+  
   Murmur3_32HashFunction(int seed) {
     this.seed = seed;
   }
@@ -60,107 +41,63 @@ final class Murmur3_32HashFunction extends AbstractStreamingHashFunction impleme
     return new Murmur3_32Hasher(seed);
   }
 
-  @Override
-  public String toString() {
-    return "Hashing.murmur3_32(" + seed + ")";
-  }
-
-  @Override public HashCode hashInt(int input) {
-    int k1 = mixK1(input);
-    int h1 = mixH1(seed, k1);
-
-    return fmix(h1, Ints.BYTES);
-  }
-
-  @Override public HashCode hashLong(long input) {
-    int low = (int) input;
-    int high = (int) (input >>> 32);
-
-    int k1 = mixK1(low);
-    int h1 = mixH1(seed, k1);
-
-    k1 = mixK1(high);
-    h1 = mixH1(h1, k1);
-
-    return fmix(h1, Longs.BYTES);
-  }
-
-  // TODO(user): Maybe implement #hashBytes instead?
-  @Override public HashCode hashString(CharSequence input) {
-    int h1 = seed;
-
-    // step through the CharSequence 2 chars at a time
-    for (int i = 1; i < input.length(); i += 2) {
-      int k1 = input.charAt(i - 1) | (input.charAt(i) << 16);
-      k1 = mixK1(k1);
-      h1 = mixH1(h1, k1);
-    }
-
-    // deal with any remaining characters
-    if ((input.length() & 1) == 1) {
-      int k1 = input.charAt(input.length() - 1);
-      k1 = mixK1(k1);
-      h1 ^= k1;
-    }
-
-    return fmix(h1, Chars.BYTES * input.length());
-  }
-
-  private static int mixK1(int k1) {
-    k1 *= C1;
-    k1 = Integer.rotateLeft(k1, 15);
-    k1 *= C2;
-    return k1;
-  }
-
-  private static int mixH1(int h1, int k1) {
-    h1 ^= k1;
-    h1 = Integer.rotateLeft(h1, 13);
-    h1 = h1 * 5 + 0xe6546b64;
-    return h1;
-  }
-
-  // Finalization mix - force all bits of a hash block to avalanche
-  private static HashCode fmix(int h1, int length) {
-    h1 ^= length;
-    h1 ^= h1 >>> 16;
-    h1 *= 0x85ebca6b;
-    h1 ^= h1 >>> 13;
-    h1 *= 0xc2b2ae35;
-    h1 ^= h1 >>> 16;
-    return HashCodes.fromInt(h1);
-  }
-
   private static final class Murmur3_32Hasher extends AbstractStreamingHasher {
-    private static final int CHUNK_SIZE = 4;
-    private int h1;
-    private int length;
+    int h1;
+    int c1 = 0xcc9e2d51;
+    int c2 = 0x1b873593;
+    int len;
 
     Murmur3_32Hasher(int seed) {
-      super(CHUNK_SIZE);
-      this.h1 = seed;
-      this.length = 0;
+      super(4);
+      h1 = seed;
     }
 
     @Override protected void process(ByteBuffer bb) {
-      int k1 = Murmur3_32HashFunction.mixK1(bb.getInt());
-      h1 = Murmur3_32HashFunction.mixH1(h1, k1);
-      length += CHUNK_SIZE;
+      int k1 = bb.getInt();
+      len += 4;
+      
+      k1 *= c1; 
+      k1 = Integer.rotateLeft(k1, 15); 
+      k1 *= c2;
+      
+      h1 ^= k1;
+      h1 = Integer.rotateLeft(h1, 13);
+      h1 = h1 * 5 + 0xe6546b64;
     }
-
+    
     @Override protected void processRemaining(ByteBuffer bb) {
-      length += bb.remaining();
+      len += bb.remaining();
       int k1 = 0;
-      for (int i = 0; bb.hasRemaining(); i += 8) {
-        k1 ^= toInt(bb.get()) << i;
+      switch (bb.remaining()) {
+        case 3:
+          k1 ^= toInt(bb.get(2)) << 16;
+          // fall through
+        case 2:
+          k1 ^= toInt(bb.get(1)) << 8;
+          // fall through
+        case 1:
+          k1 ^= toInt(bb.get(0));
+          // fall through
+        default:
+          k1 *= c1;
+          k1 = Integer.rotateLeft(k1, 15);
+          k1 *= c2;
+          h1 ^= k1;
       }
-      h1 ^= Murmur3_32HashFunction.mixK1(k1);
     }
-
+    
     @Override public HashCode makeHash() {
-      return Murmur3_32HashFunction.fmix(h1, length);
+      h1 ^= len;
+
+      h1 ^= h1 >>> 16;
+      h1 *= 0x85ebca6b;
+      h1 ^= h1 >>> 13;
+      h1 *= 0xc2b2ae35;
+      h1 ^= h1 >>> 16;
+          
+      return HashCodes.fromInt(h1);
     }
   }
-
+  
   private static final long serialVersionUID = 0L;
 }