content: /*
   * Licensed 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.bookkeeper.common.hash;
  
  import io.netty.buffer.ByteBuf;
  
  /**
   * Murmur3 is successor to Murmur2 fast non-crytographic hash algorithms.
   *
   * Murmur3 32 and 128 bit variants.
   * 32-bit Java port of https://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp#94
   * 128-bit Java port of https://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp#255
   *
   * This is a public domain code with no copyrights.
   * From homepage of MurmurHash (https://code.google.com/p/smhasher/),
   * "All MurmurHash versions are public domain software, and the author disclaims all copyright
   * to their code."
   */
  public class Murmur3 {
      // Constants for 32 bit variant
      private static final int C1_32 = 0xcc9e2d51;
      private static final int C2_32 = 0x1b873593;
      private static final int R1_32 = 15;
      private static final int R2_32 = 13;
      private static final int M_32 = 5;
      private static final int N_32 = 0xe6546b64;
  
      // Constants for 128 bit variant
      private static final long C1 = 0x87c37b91114253d5L;
      private static final long C2 = 0x4cf5ad432745937fL;
      private static final int R1 = 31;
      private static final int R2 = 27;
      private static final int R3 = 33;
      private static final int M = 5;
      private static final int N1 = 0x52dce729;
      private static final int N2 = 0x38495ab5;
  
      public static final int DEFAULT_SEED = 104729;
  
      /**
       * Murmur3 32-bit variant.
       *
       * @param data - input byte array
       * @return - hashcode
       */
      public static int hash32(byte[] data) {
          return hash32(data, 0, data.length, DEFAULT_SEED);
      }
  
      /**
       * Murmur3 32-bit variant.
       *
       * @param data - input byte array
       * @param length - length of array
       * @return - hashcode
       */
      public static int hash32(byte[] data, int length) {
          return hash32(data, 0, length, DEFAULT_SEED);
      }
  
      /**
       * Murmur3 32-bit variant.
       *
       * @param data   - input byte array
       * @param length - length of array
       * @param seed   - seed. (default 0)
       * @return - hashcode
       */
      public static int hash32(byte[] data, int length, int seed) {
          return hash32(data, 0, length, seed);
      }
  
      /**
       * Murmur3 32-bit variant.
       *
       * @param data   - input byte array
       * @param offset - offset of data
       * @param length - length of array
       * @param seed   - seed. (default 0)
       * @return - hashcode
       */
      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 i_4 = i << 2;
              int k = (data[offset + i_4] & 0xff)
                  | ((data[offset + i_4 + 1] & 0xff) << 8)
                  | ((data[offset + i_4 + 2] & 0xff) << 16)
                  | ((data[offset + i_4 + 3] & 0xff) << 24);
  
              // 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;
          }
  
          // tail
          int idx = nblocks << 2;
          int k1 = 0;
          switch (length - idx) {
              case 3:
                  k1 ^= data[offset + idx + 2] << 16;
              case 2:
                  k1 ^= data[offset + idx + 1] << 8;
              case 1:
                  k1 ^= data[offset + idx];
  
                  // mix functions
                  k1 *= C1_32;
                  k1 = Integer.rotateLeft(k1, R1_32);
                  k1 *= C2_32;
                  hash ^= k1;
          }
  
          // finalization
          hash ^= length;
          hash ^= (hash >>> 16);
          hash *= 0x85ebca6b;
          hash ^= (hash >>> 13);
          hash *= 0xc2b2ae35;
          hash ^= (hash >>> 16);
  
          return hash;
      }
  
      public static int hash32(ByteBuf data, int offset, int length, int seed) {
          int hash = seed;
          final int nblocks = length >> 2;
  
          // body
          for (int i = 0; i < nblocks; i++) {
              int i_4 = i << 2;
              int k = (data.getByte(offset + i_4) & 0xff)
                  | ((data.getByte(offset + i_4 + 1) & 0xff) << 8)
                  | ((data.getByte(offset + i_4 + 2) & 0xff) << 16)
                  | ((data.getByte(offset + i_4 + 3) & 0xff) << 24);
  
              // 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;
          }
  
          // tail
          int idx = nblocks << 2;
          int k1 = 0;
          switch (length - idx) {
              case 3:
                  k1 ^= data.getByte(offset + idx + 2) << 16;
              case 2:
                  k1 ^= data.getByte(offset + idx + 1) << 8;
              case 1:
                  k1 ^= data.getByte(offset + idx);
  
                  // mix functions
                  k1 *= C1_32;
                  k1 = Integer.rotateLeft(k1, R1_32);
                  k1 *= C2_32;
                  hash ^= k1;
          }
  
          // finalization
          hash ^= length;
          hash ^= (hash >>> 16);
          hash *= 0x85ebca6b;
          hash ^= (hash >>> 13);
          hash *= 0xc2b2ae35;
          hash ^= (hash >>> 16);
  
          return hash;
      }
  
      /**
       * Murmur3 128-bit variant.
       *
       * @param data - input byte array
       * @return - hashcode (2 longs)
       */
      public static long[] hash128(byte[] data) {
          return hash128(data, 0, data.length, DEFAULT_SEED);
      }
  
      /**
       * Murmur3 128-bit variant.
       *
       * @param data   - input byte array
       * @param offset - the first element of array
       * @param length - length of array
       * @param seed   - seed. (default is 0)
       * @return - hashcode (2 longs)
       */
      public static long[] hash128(byte[] data, int offset, int length, long seed) {
          long h1 = seed;
          long h2 = seed;
          final int nblocks = length >> 4;
  
          // body
          for (int i = 0; i < nblocks; i++) {
              final int i16 = i << 4;
              long k1 = ((long) data[offset + i16] & 0xff)
                  | (((long) data[offset + i16 + 1] & 0xff) << 8)
                  | (((long) data[offset + i16 + 2] & 0xff) << 16)
                  | (((long) data[offset + i16 + 3] & 0xff) << 24)
                  | (((long) data[offset + i16 + 4] & 0xff) << 32)
                  | (((long) data[offset + i16 + 5] & 0xff) << 40)
                  | (((long) data[offset + i16 + 6] & 0xff) << 48)
                  | (((long) data[offset + i16 + 7] & 0xff) << 56);
  
              long k2 = ((long) data[offset + i16 + 8] & 0xff)
                  | (((long) data[offset + i16 + 9] & 0xff) << 8)
                  | (((long) data[offset + i16 + 10] & 0xff) << 16)
                  | (((long) data[offset + i16 + 11] & 0xff) << 24)
                  | (((long) data[offset + i16 + 12] & 0xff) << 32)
                  | (((long) data[offset + i16 + 13] & 0xff) << 40)
                  | (((long) data[offset + i16 + 14] & 0xff) << 48)
                  | (((long) data[offset + i16 + 15] & 0xff) << 56);
  
              // mix functions for k1
              k1 *= C1;
              k1 = Long.rotateLeft(k1, R1);
              k1 *= C2;
              h1 ^= k1;
              h1 = Long.rotateLeft(h1, R2);
              h1 += h2;
              h1 = h1 * M + N1;
  
              // mix functions for k2
              k2 *= C2;
              k2 = Long.rotateLeft(k2, R3);
              k2 *= C1;
              h2 ^= k2;
              h2 = Long.rotateLeft(h2, R1);
              h2 += h1;
              h2 = h2 * M + N2;
          }
  
          // tail
          long k1 = 0;
          long k2 = 0;
          int tailStart = nblocks << 4;
          switch (length - tailStart) {
              case 15:
                  k2 ^= (long) (data[offset + tailStart + 14] & 0xff) << 48;
              case 14:
                  k2 ^= (long) (data[offset + tailStart + 13] & 0xff) << 40;
              case 13:
                  k2 ^= (long) (data[offset + tailStart + 12] & 0xff) << 32;
              case 12:
                  k2 ^= (long) (data[offset + tailStart + 11] & 0xff) << 24;
              case 11:
                  k2 ^= (long) (data[offset + tailStart + 10] & 0xff) << 16;
              case 10:
                  k2 ^= (long) (data[offset + tailStart + 9] & 0xff) << 8;
              case 9:
                  k2 ^= (long) (data[offset + tailStart + 8] & 0xff);
                  k2 *= C2;
                  k2 = Long.rotateLeft(k2, R3);
                  k2 *= C1;
                  h2 ^= k2;
  
              case 8:
                  k1 ^= (long) (data[offset + tailStart + 7] & 0xff) << 56;
              case 7:
                  k1 ^= (long) (data[offset + tailStart + 6] & 0xff) << 48;
              case 6:
                  k1 ^= (long) (data[offset + tailStart + 5] & 0xff) << 40;
              case 5:
                  k1 ^= (long) (data[offset + tailStart + 4] & 0xff) << 32;
              case 4:
                  k1 ^= (long) (data[offset + tailStart + 3] & 0xff) << 24;
              case 3:
                  k1 ^= (long) (data[offset + tailStart + 2] & 0xff) << 16;
              case 2:
                  k1 ^= (long) (data[offset + tailStart + 1] & 0xff) << 8;
              case 1:
                  k1 ^= (long) (data[offset + tailStart] & 0xff);
                  k1 *= C1;
                  k1 = Long.rotateLeft(k1, R1);
                  k1 *= C2;
                  h1 ^= k1;
          }
  
          // finalization
          h1 ^= length;
          h2 ^= length;
  
          h1 += h2;
          h2 += h1;
  
          h1 = fmix64(h1);
          h2 = fmix64(h2);
  
          h1 += h2;
          h2 += h1;
  
          return new long[]{h1, h2};
      }
  
      /**
       * Murmur3 128-bit variant.
       *
       * @param data   - input byte array
       * @param offset - the first element of array
       * @param length - length of array
       * @param seed   - seed. (default is 0)
       * @return - hashcode (2 longs)
       */
      public static long[] hash128(ByteBuf data, int offset, int length, long seed) {
          long h1 = seed;
          long h2 = seed;
          final int nblocks = length >> 4;
  
          // body
          for (int i = 0; i < nblocks; i++) {
              final int i16 = i << 4;
              long k1 = ((long) data.getByte(offset + i16) & 0xff)
                  | (((long) data.getByte(offset + i16 + 1) & 0xff) << 8)
                  | (((long) data.getByte(offset + i16 + 2) & 0xff) << 16)
                  | (((long) data.getByte(offset + i16 + 3) & 0xff) << 24)
                  | (((long) data.getByte(offset + i16 + 4) & 0xff) << 32)
                  | (((long) data.getByte(offset + i16 + 5) & 0xff) << 40)
                  | (((long) data.getByte(offset + i16 + 6) & 0xff) << 48)
                  | (((long) data.getByte(offset + i16 + 7) & 0xff) << 56);
  
              long k2 = ((long) data.getByte(offset + i16 + 8) & 0xff)
                  | (((long) data.getByte(offset + i16 + 9) & 0xff) << 8)
                  | (((long) data.getByte(offset + i16 + 10) & 0xff) << 16)
                  | (((long) data.getByte(offset + i16 + 11) & 0xff) << 24)
                  | (((long) data.getByte(offset + i16 + 12) & 0xff) << 32)
                  | (((long) data.getByte(offset + i16 + 13) & 0xff) << 40)
                  | (((long) data.getByte(offset + i16 + 14) & 0xff) << 48)
                  | (((long) data.getByte(offset + i16 + 15) & 0xff) << 56);
  
              // mix functions for k1
              k1 *= C1;
              k1 = Long.rotateLeft(k1, R1);
              k1 *= C2;
              h1 ^= k1;
              h1 = Long.rotateLeft(h1, R2);
              h1 += h2;
              h1 = h1 * M + N1;
  
              // mix functions for k2
              k2 *= C2;
              k2 = Long.rotateLeft(k2, R3);
              k2 *= C1;
              h2 ^= k2;
              h2 = Long.rotateLeft(h2, R1);
              h2 += h1;
              h2 = h2 * M + N2;
          }
  
          // tail
          long k1 = 0;
          long k2 = 0;
          int tailStart = nblocks << 4;
          switch (length - tailStart) {
              case 15:
                  k2 ^= (long) (data.getByte(offset + tailStart + 14) & 0xff) << 48;
              case 14:
                  k2 ^= (long) (data.getByte(offset + tailStart + 13) & 0xff) << 40;
              case 13:
                  k2 ^= (long) (data.getByte(offset + tailStart + 12) & 0xff) << 32;
              case 12:
                  k2 ^= (long) (data.getByte(offset + tailStart + 11) & 0xff) << 24;
              case 11:
                  k2 ^= (long) (data.getByte(offset + tailStart + 10) & 0xff) << 16;
              case 10:
                  k2 ^= (long) (data.getByte(offset + tailStart + 9) & 0xff) << 8;
              case 9:
                  k2 ^= (long) (data.getByte(offset + tailStart + 8) & 0xff);
                  k2 *= C2;
                  k2 = Long.rotateLeft(k2, R3);
                  k2 *= C1;
                  h2 ^= k2;
  
              case 8:
                  k1 ^= (long) (data.getByte(offset + tailStart + 7) & 0xff) << 56;
              case 7:
                  k1 ^= (long) (data.getByte(offset + tailStart + 6) & 0xff) << 48;
              case 6:
                  k1 ^= (long) (data.getByte(offset + tailStart + 5) & 0xff) << 40;
              case 5:
                  k1 ^= (long) (data.getByte(offset + tailStart + 4) & 0xff) << 32;
              case 4:
                  k1 ^= (long) (data.getByte(offset + tailStart + 3) & 0xff) << 24;
              case 3:
                  k1 ^= (long) (data.getByte(offset + tailStart + 2) & 0xff) << 16;
              case 2:
                  k1 ^= (long) (data.getByte(offset + tailStart + 1) & 0xff) << 8;
              case 1:
                  k1 ^= (long) (data.getByte(offset + tailStart) & 0xff);
                  k1 *= C1;
                  k1 = Long.rotateLeft(k1, R1);
                  k1 *= C2;
                  h1 ^= k1;
          }
  
          // finalization
          h1 ^= length;
          h2 ^= length;
  
          h1 += h2;
          h2 += h1;
  
          h1 = fmix64(h1);
          h2 = fmix64(h2);
  
          h1 += h2;
          h2 += h1;
  
          return new long[]{h1, h2};
      }
  
      private static long fmix64(long h) {
          h ^= (h >>> 33);
          h *= 0xff51afd7ed558ccdL;
          h ^= (h >>> 33);
          h *= 0xc4ceb9fe1a85ec53L;
          h ^= (h >>> 33);
          return h;
      }
  
  }
  