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 io.airlift.slice;
  
  import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  
  public final class Murmur3Hash32
  {
      private static final int C1 = 0xcc9e2d51;
      private static final int C2 = 0x1b873593;
  
      private static final int DEFAULT_SEED = 0;
  
      private Murmur3Hash32() {}
  
      public static int hash(Slice data)
      {
          return hash(data, 0, data.length());
      }
  
      public static int hash(Slice data, int offset, int length)
      {
          return hash(DEFAULT_SEED, data, offset, length);
      }
  
      @SuppressFBWarnings({"SF_SWITCH_NO_DEFAULT", "SF_SWITCH_FALLTHROUGH"})
      public static int hash(int seed, Slice data, int offset, int length)
      {
          final int fastLimit = offset + length - SizeOf.SIZE_OF_INT + 1;
  
          int h1 = seed;
  
          int current = offset;
          while (current < fastLimit) {
              int k1 = mixK1(data.getInt(current));
              current += SizeOf.SIZE_OF_INT;
              h1 = mixH1(h1, k1);
          }
  
          int k1 = 0;
  
          switch (length & 3) {
              case 3:
                  k1 ^= ((int) data.getUnsignedByte(current + 2)) << 16;
              case 2:
                  k1 ^= ((int) data.getUnsignedByte(current + 1)) << 8;
              case 1:
                  k1 ^= ((int) data.getUnsignedByte(current + 0)) << 0;
          }
  
          h1 ^= mixK1(k1);
  
          return fmix(h1, length);
      }
  
      /**
       * Special-purpose version for hashing a single int value. Value is treated as little-endian
       */
      public static int hash(int input)
      {
          int k1 = mixK1(input);
          int h1 = mixH1(DEFAULT_SEED, k1);
  
          return fmix(h1, SizeOf.SIZE_OF_INT);
      }
  
      /**
       * Special-purpose version for hashing a single long value. Value is treated as little-endian
       */
      public static int hash(long input)
      {
          int low = (int) input;
          int high = (int) (input >>> 32);
  
          int k1 = mixK1(low);
          int h1 = mixH1(DEFAULT_SEED, k1);
  
          k1 = mixK1(high);
          h1 = mixH1(h1, k1);
  
          return fmix(h1, SizeOf.SIZE_OF_LONG);
      }
  
      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;
      }
  
      private static int fmix(int h1, int length)
      {
          h1 ^= length;
          h1 ^= h1 >>> 16;
          h1 *= 0x85ebca6b;
          h1 ^= h1 >>> 13;
          h1 *= 0xc2b2ae35;
          h1 ^= h1 >>> 16;
          return h1;
      }
  }
  