content: // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
  // for details. All rights reserved. Use of this source code is governed by a
  // BSD-style license that can be found in the LICENSE file.
  part of dart.math;
  
  /**
   * This is the [Jenkins hash function][1] but using masking to keep
   * values in SMI range.
   *
   * [1]: http://en.wikipedia.org/wiki/Jenkins_hash_function
   *
   * Use:
   * Hash each value with the hash of the previous value, then get the final
   * hash by calling finish.
   *
   *     var hash = 0;
   *     for (var value in values) {
   *       hash = JenkinsSmiHash.combine(hash, value.hashCode);
   *     }
   *     hash = JenkinsSmiHash.finish(hash);
   */
  class _JenkinsSmiHash {
    // TODO(11617): This class should be optimized and standardized elsewhere.
  
    static int combine(int hash, int value) {
      hash = 0x1fffffff & (hash + value);
      hash = 0x1fffffff & (hash + ((0x0007ffff & hash) << 10));
      return hash ^ (hash >> 6);
    }
  
    static int finish(int hash) {
      hash = 0x1fffffff & (hash + ((0x03ffffff & hash) <<  3));
      hash = hash ^ (hash >> 11);
      return 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
    }
  
    static int hash2(a, b) => finish(combine(combine(0, a), b));
  
    static int hash4(a, b, c, d) =>
        finish(combine(combine(combine(combine(0, a), b), c), d));
  }
  