Github user amansinha100 commented on a diff in the pull request:
https://github.com/apache/drill/pull/430#discussion_r56900294
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/MurmurHash3.java
---
@@ -0,0 +1,264 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+
+package org.apache.drill.exec.expr.fn.impl;
+
+import io.netty.buffer.DrillBuf;
+import io.netty.util.internal.PlatformDependent;
+
+
+/**
+ *
+ * MurmurHash3 was written by Austin Appleby, and is placed in the public
+ * domain.
+ * See http://smhasher.googlecode.com/svn/trunk/MurmurHash3.cpp
+ * MurmurHash3_x64_128
+ * MurmurHash3_x86_32
+ */
+public final class MurmurHash3 extends DrillHash{
+
+ public final class LongPair {
+ public long val1;
+ public long val2;
+ }
+
+ public static final long fmix64(long k) {
+ k ^= k >>> 33;
+ k *= 0xff51afd7ed558ccdL;
+ k ^= k >>> 33;
+ k *= 0xc4ceb9fe1a85ec53L;
+ k ^= k >>> 33;
+ return k;
+ }
+
+
+
+ /*
+ Take 64 bit of murmur3_128's output
+ */
+ public static long murmur3_64(long bStart, long bEnd, DrillBuf buffer,
int seed) {
+
+ long h1 = seed & 0x00000000FFFFFFFFL;
+ long h2 = seed & 0x00000000FFFFFFFFL;
+
+ final long c1 = 0x87c37b91114253d5L;
+ final long c2 = 0x4cf5ad432745937fL;
+ long start = buffer.memoryAddress() + bStart;
+ long end = buffer.memoryAddress() + bEnd;
+ long length = end - start;
+ long roundedEnd = start + ( length & 0xFFFFFFF0); // round down to 16
byte block
+ for (long i=start; i<roundedEnd; i+=16) {
+ long k1 = getLongLittleEndian(i);
+ long k2 = getLongLittleEndian(i+8);
+ k1 *= c1; k1 = Long.rotateLeft(k1,31); k1 *= c2; h1 ^= k1;
+ h1 = Long.rotateLeft(h1,27); h1 += h2; h1 = h1*5+0x52dce729;
+ k2 *= c2; k2 = Long.rotateLeft(k2,33); k2 *= c1; h2 ^= k2;
+ h2 = Long.rotateLeft(h2,31); h2 += h1; h2 = h2*5+0x38495ab5;
+ }
+
+ long k1 = 0;
+ long k2 = 0;
+
+ // tail
+ switch ((int)length & 15) {
+ case 15: k2 = (PlatformDependent.getByte(roundedEnd+14) & 0xffL) <<
48;
+ case 14: k2 |= (PlatformDependent.getByte(roundedEnd+13) & 0xffL) <<
40;
+ case 13: k2 |= (PlatformDependent.getByte(roundedEnd+12) & 0xffL) <<
32;
+ case 12: k2 |= (PlatformDependent.getByte(roundedEnd+11) & 0xffL) <<
24;
+ case 11: k2 |= (PlatformDependent.getByte(roundedEnd+10) & 0xffL) <<
16;
+ case 10: k2 |= (PlatformDependent.getByte(roundedEnd+ 9) & 0xffL) <<
8;
+ case 9: k2 |= (PlatformDependent.getByte(roundedEnd+ 8) & 0xffL);
+ k2 *= c2; k2 = Long.rotateLeft(k2, 33); k2 *= c1; h2 ^= k2;
--- End diff --
Some check style comments: these statements should be split up into
separate lines..
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