murmurhash.js

(function(){
  const _global = this;

  const createBuffer = (val) => new TextEncoder().encode(val)

  /**
   * JS Implementation of MurmurHash2
   *
   * @author <a href="mailto:gary.court@gmail.com">Gary Court</a>
   * @see http://github.com/garycourt/murmurhash-js
   * @author <a href="mailto:aappleby@gmail.com">Austin Appleby</a>
   * @see http://sites.google.com/site/murmurhash/
   *
   * @param {Uint8Array | string} str ASCII only
   * @param {number} seed Positive integer only
   * @return {number} 32-bit positive integer hash
   */
  function MurmurHashV2(str, seed) {
    if (typeof str === 'string') str = createBuffer(str);
    let
      l = str.length,
      h = seed ^ l,
      i = 0,
      k;

    while (l >= 4) {
      k =
        ((str[i] & 0xff)) |
        ((str[++i] & 0xff) << 8) |
        ((str[++i] & 0xff) << 16) |
        ((str[++i] & 0xff) << 24);

      k = (((k & 0xffff) * 0x5bd1e995) + ((((k >>> 16) * 0x5bd1e995) & 0xffff) << 16));
      k ^= k >>> 24;
      k = (((k & 0xffff) * 0x5bd1e995) + ((((k >>> 16) * 0x5bd1e995) & 0xffff) << 16));

    h = (((h & 0xffff) * 0x5bd1e995) + ((((h >>> 16) * 0x5bd1e995) & 0xffff) << 16)) ^ k;

      l -= 4;
      ++i;
    }

    switch (l) {
    case 3: h ^= (str[i + 2] & 0xff) << 16;
    case 2: h ^= (str[i + 1] & 0xff) << 8;
    case 1: h ^= (str[i] & 0xff);
            h = (((h & 0xffff) * 0x5bd1e995) + ((((h >>> 16) * 0x5bd1e995) & 0xffff) << 16));
    }

    h ^= h >>> 13;
    h = (((h & 0xffff) * 0x5bd1e995) + ((((h >>> 16) * 0x5bd1e995) & 0xffff) << 16));
    h ^= h >>> 15;

    return h >>> 0;
  };

  /*
   * JS Implementation of MurmurHash3 (r136) (as of May 20, 2011)
   *
   * @author <a href="mailto:gary.court@gmail.com">Gary Court</a>
   * @see http://github.com/garycourt/murmurhash-js
   * @author <a href="mailto:aappleby@gmail.com">Austin Appleby</a>
   * @see http://sites.google.com/site/murmurhash/
   *
   * @param {Uint8Array | string} key ASCII only
   * @param {number} seed Positive integer only
   * @return {number} 32-bit positive integer hash
   */
  function MurmurHashV3(key, seed) {
    if (typeof key === 'string') key = createBuffer(key);

    let remainder, bytes, h1, h1b, c1, c1b, c2, c2b, k1, i;

    remainder = key.length & 3; // key.length % 4
    bytes = key.length - remainder;
    h1 = seed;
    c1 = 0xcc9e2d51;
    c2 = 0x1b873593;
    i = 0;

    while (i < bytes) {
        k1 =
          ((key[i] & 0xff)) |
          ((key[++i] & 0xff) << 8) |
          ((key[++i] & 0xff) << 16) |
          ((key[++i] & 0xff) << 24);
      ++i;

      k1 = ((((k1 & 0xffff) * c1) + ((((k1 >>> 16) * c1) & 0xffff) << 16))) & 0xffffffff;
      k1 = (k1 << 15) | (k1 >>> 17);
      k1 = ((((k1 & 0xffff) * c2) + ((((k1 >>> 16) * c2) & 0xffff) << 16))) & 0xffffffff;

      h1 ^= k1;
          h1 = (h1 << 13) | (h1 >>> 19);
      h1b = ((((h1 & 0xffff) * 5) + ((((h1 >>> 16) * 5) & 0xffff) << 16))) & 0xffffffff;
      h1 = (((h1b & 0xffff) + 0x6b64) + ((((h1b >>> 16) + 0xe654) & 0xffff) << 16));
    }

    k1 = 0;

    switch (remainder) {
      case 3: k1 ^= (key[i + 2] & 0xff) << 16;
      case 2: k1 ^= (key[i + 1] & 0xff) << 8;
      case 1: k1 ^= (key[i] & 0xff);

      k1 = (((k1 & 0xffff) * c1) + ((((k1 >>> 16) * c1) & 0xffff) << 16)) & 0xffffffff;
      k1 = (k1 << 15) | (k1 >>> 17);
      k1 = (((k1 & 0xffff) * c2) + ((((k1 >>> 16) * c2) & 0xffff) << 16)) & 0xffffffff;
      h1 ^= k1;
    }

    h1 ^= key.length;

    h1 ^= h1 >>> 16;
    h1 = (((h1 & 0xffff) * 0x85ebca6b) + ((((h1 >>> 16) * 0x85ebca6b) & 0xffff) << 16)) & 0xffffffff;
    h1 ^= h1 >>> 13;
    h1 = ((((h1 & 0xffff) * 0xc2b2ae35) + ((((h1 >>> 16) * 0xc2b2ae35) & 0xffff) << 16))) & 0xffffffff;
    h1 ^= h1 >>> 16;

    return h1 >>> 0;
  }

  const murmur = MurmurHashV3;
  murmur.v2 = MurmurHashV2;
  murmur.v3 = MurmurHashV3;

  if (typeof(module) != 'undefined') {
    module.exports = murmur;
  } else {
    const _previousRoot = _global.murmur;
    murmur.noConflict = function() {
      _global.murmur = _previousRoot;
      return murmur;
    }
    _global.murmur = murmur;
  }
}());