修复murmur3_32实现错误

CHANGELOG.md

@@ -11,6 +11,7 @@
 
 ### 🐞Bug修复
 * 【core   】     修复FileNameUtil.cleanInvalid无法去除换行符问题（issue#I5RMZV@Gitee）
+* 【core   】     修复murmur3_32实现错误（pr#2616@Github）
 
 -------------------------------------------------------------------------------------------------------------
 

hutool-core/src/main/java/cn/hutool/core/lang/hash/MurmurHash.java

@@ -17,10 +17,10 @@ import java.nio.charset.Charset;
  * 128-bit Java port of https://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp#255
  * </p>
  *
- * @author looly,Simhash4J
+ * @author looly, Simhash4J
  * @since 4.3.3
  */
-public class MurmurHash implements Serializable{
+public class MurmurHash implements Serializable {
 	private static final long serialVersionUID = 1L;
 
 	// Constants for 32 bit variant
@@ -74,26 +74,34 @@ public class MurmurHash implements Serializable{
 	 * @return Hash值
 	 */
 	public static int hash32(byte[] data, int length, int seed) {
+		return hash32(data, 0, length, seed);
+	}
+
+	/**
+	 * Murmur3 32-bit Hash值计算
+	 *
+	 * @param data   数据
+	 * @param offset 数据开始位置
+	 * @param length 长度
+	 * @param seed   种子，默认0
+	 * @return Hash值
+	 */
+	public static int hash32(byte[] data, int offset, int length, int seed) {
 		int hash = seed;
 		final int nblocks = length >> 2;
 
 		// body
 		for (int i = 0; i < nblocks; i++) {
-			int i4 = i << 2;
-			int k = ByteUtil.bytesToInt(data, i4, DEFAULT_ORDER);
-
+			final int i4 = offset  + (i << 2);
+			final int k = ByteUtil.bytesToInt(data, i4, DEFAULT_ORDER);
 			// mix functions
-			k *= C1_32;
-			k = Integer.rotateLeft(k, R1_32);
-			k *= C2_32;
-			hash ^= k;
-			hash = Integer.rotateLeft(hash, R2_32) * M_32 + N_32;
+			hash = mix32(k, hash);
 		}
 
 		// tail
-		int idx = nblocks << 2;
+		final int idx = offset + (nblocks << 2);
 		int k1 = 0;
-		switch (length - idx) {
+		switch (offset + length - idx) {
 			case 3:
 				k1 ^= (data[idx + 2] & 0xff) << 16;
 			case 2:
@@ -110,13 +118,7 @@ public class MurmurHash implements Serializable{
 
 		// finalization
 		hash ^= length;
-		hash ^= (hash >>> 16);
-		hash *= 0x85ebca6b;
-		hash ^= (hash >>> 13);
-		hash *= 0xc2b2ae35;
-		hash ^= (hash >>> 16);
-
-		return hash;
+		return fmix32(hash);
 	}
 
 	/**
@@ -133,7 +135,6 @@ public class MurmurHash implements Serializable{
 	 * Murmur3 64-bit 算法<br>
 	 * This is essentially MSB 8 bytes of Murmur3 128-bit variant.
 	 *
-	 *
 	 * @param data 数据
 	 * @return Hash值
 	 */
@@ -142,7 +143,7 @@ public class MurmurHash implements Serializable{
 	}
 
 	/**
-	 * Murmur3 64-bit 算法 <br>
+	 * 类Murmur3 64-bit 算法 <br>
 	 * This is essentially MSB 8 bytes of Murmur3 128-bit variant.
 	 *
 	 * @param data   数据
@@ -227,13 +228,29 @@ public class MurmurHash implements Serializable{
 	 * @return Hash值(2 longs)
 	 */
 	public static long[] hash128(byte[] data, int length, int seed) {
+		return hash128(data, 0, length, seed);
+	}
+
+	/**
+	 * Murmur3 128-bit variant.
+	 *
+	 * @param data   数据
+	 * @param offset 数据开始位置
+	 * @param length 长度
+	 * @param seed   种子，默认0
+	 * @return Hash值(2 longs)
+	 */
+	public static long[] hash128(byte[] data, int offset, int length, int seed) {
+		// 避免负数的种子
+		seed &= 0xffffffffL;
+
 		long h1 = seed;
 		long h2 = seed;
 		final int nblocks = length >> 4;
 
 		// body
 		for (int i = 0; i < nblocks; i++) {
-			final int i16 = i << 4;
+			final int i16 = offset + (i << 4);
 			long k1 = ByteUtil.bytesToLong(data, i16, DEFAULT_ORDER);
 			long k2 = ByteUtil.bytesToLong(data, i16 + 8, DEFAULT_ORDER);
 
@@ -259,8 +276,8 @@ public class MurmurHash implements Serializable{
 		// tail
 		long k1 = 0;
 		long k2 = 0;
-		int tailStart = nblocks << 4;
-		switch (length - tailStart) {
+		final int tailStart = offset + (nblocks << 4);
+		switch (offset + length - tailStart) {
 			case 15:
 				k2 ^= (long) (data[tailStart + 14] & 0xff) << 48;
 			case 14:
@@ -315,7 +332,24 @@ public class MurmurHash implements Serializable{
 		h1 += h2;
 		h2 += h1;
 
-		return new long[] { h1, h2 };
+		return new long[]{h1, h2};
+	}
+
+	private static int mix32(int k, int hash) {
+		k *= C1_32;
+		k = Integer.rotateLeft(k, R1_32);
+		k *= C2_32;
+		hash ^= k;
+		return Integer.rotateLeft(hash, R2_32) * M_32 + N_32;
+	}
+
+	private static int fmix32(int hash) {
+		hash ^= (hash >>> 16);
+		hash *= 0x85ebca6b;
+		hash ^= (hash >>> 13);
+		hash *= 0xc2b2ae35;
+		hash ^= (hash >>> 16);
+		return hash;
 	}
 
 	private static long fmix64(long h) {

hutool-core/src/test/java/cn/hutool/core/lang/hash/MurmurHashTest.java

@@ -4,7 +4,7 @@ import cn.hutool.core.util.StrUtil;
 import org.junit.Assert;
 import org.junit.Test;
 
-public class MurMurHashTest {
+public class MurmurHashTest {
 
 	@Test
 	public void hash32Test() {