code: /*
   * Copyright 2012-2018 Chronicle Map Contributors
   *
   * 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 net.openhft.chronicle.hash.impl.stage.entry;
  
  public enum ChecksumHashing {
      ; // none
  
      /**
       * A smart procedure copied from CityHash/FarmHash, see the full implementation in
       * Zero-allocation-hashing or Chronicle-Algorithms
       */
      public static long hash8To16Bytes(long len, long first8Bytes, long last8Bytes) {
          long K2 = 0x9ae16a3b2f90404fL;
          long mul = K2 + (len << 1);
          long a = first8Bytes + K2;
          long c = ((last8Bytes >>> 37) | (last8Bytes << 27)) * mul + a;
          long d = (((a >>> 25) | (a << 39)) + last8Bytes) * mul;
          long a1 = (c ^ d) * mul ^ ((c ^ d) * mul >>> 47);
          return ((d ^ a1) * mul ^ ((d ^ a1) * mul >>> 47)) * mul;
      }
  }
  