murmurhash3

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Preparation HTML

<script>
/**
 * 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 {string} key ASCII only
 * @param {number} seed Positive integer only
 * @return {number} 32-bit positive integer hash 
 */

function murmurhash3_32_gc(key, seed) {
  var 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.charCodeAt(i) & 0xff)) | ((key.charCodeAt(++i) & 0xff) << 8) | ((key.charCodeAt(++i) & 0xff) << 16) | ((key.charCodeAt(++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.charCodeAt(i + 2) & 0xff) << 16;
  case 2:
    k1 ^= (key.charCodeAt(i + 1) & 0xff) << 8;
  case 1:
    k1 ^= (key.charCodeAt(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;
}

/*
 *  The MurmurHash3 algorithm was created by Austin Appleby.  This JavaScript port was authored
 *  by Peter Zotov (based on Java port by Yonik Seeley) and is placed into the public domain.
 *  The author hereby disclaims copyright to this source code.
 *
 *  This produces exactly the same hash values as the final C++ version of MurmurHash3 and
 *  is thus suitable for producing the same hash values across platforms.
 *
 *  There are two versions of this hash implementation. First interprets the string as a
 *  sequence of bytes, ignoring most significant byte of each codepoint. The second one
 *  interprets the string as a UTF-16 codepoint sequence, and appends each 16-bit codepoint
 *  to the hash independently. The latter mode was not written to be compatible with
 *  any other implementation, but it should offer better performance for JavaScript-only
 *  applications.
 *
 *  See http://github.com/whitequark/murmurhash3-js for future updates to this file.
 */

var MurmurHash3 = {
  mul32: function(m, n) {
    var nlo = n & 0xffff;
    var nhi = n - nlo;
    return ((nhi * m | 0) + (nlo * m | 0)) | 0;
  },

  hashBytes: function(data, len, seed) {
    var c1 = 0xcc9e2d51,
        c2 = 0x1b873593;

    var h1 = seed;
    var roundedEnd = len & ~0x3;

    for (var i = 0; i < roundedEnd; i += 4) {
      var k1 = (data.charCodeAt(i) & 0xff) | ((data.charCodeAt(i + 1) & 0xff) << 8) | ((data.charCodeAt(i + 2) & 0xff) << 16) | ((data.charCodeAt(i + 3) & 0xff) << 24);

      k1 = this.mul32(k1, c1);
      k1 = ((k1 & 0x1ffff) << 15) | (k1 >>> 17); // ROTL32(k1,15);
      k1 = this.mul32(k1, c2);

      h1 ^= k1;
      h1 = ((h1 & 0x7ffff) << 13) | (h1 >>> 19); // ROTL32(h1,13);
      h1 = (h1 * 5 + 0xe6546b64) | 0;
    }

    k1 = 0;

    switch (len % 4) {
    case 3:
      k1 = (data.charCodeAt(roundedEnd + 2) & 0xff) << 16;
      // fallthrough
    case 2:
      k1 |= (data.charCodeAt(roundedEnd + 1) & 0xff) << 8;
      // fallthrough
    case 1:
      k1 |= (data.charCodeAt(roundedEnd) & 0xff);
      k1 = this.mul32(k1, c1);
      k1 = ((k1 & 0x1ffff) << 15) | (k1 >>> 17); // ROTL32(k1,15);
      k1 = this.mul32(k1, c2);
      h1 ^= k1;
    }

    // finalization
    h1 ^= len;

    // fmix(h1);
    h1 ^= h1 >>> 16;
    h1 = this.mul32(h1, 0x85ebca6b);
    h1 ^= h1 >>> 13;
    h1 = this.mul32(h1, 0xc2b2ae35);
    h1 ^= h1 >>> 16;

    return h1;
  },

  hashString: function(data, len, seed) {
    var c1 = 0xcc9e2d51,
        c2 = 0x1b873593;

    var h1 = seed;
    var roundedEnd = len & ~0x1;

    for (var i = 0; i < roundedEnd; i += 2) {
      var k1 = data.charCodeAt(i) | (data.charCodeAt(i + 1) << 16);

      k1 = this.mul32(k1, c1);
      k1 = ((k1 & 0x1ffff) << 15) | (k1 >>> 17); // ROTL32(k1,15);
      k1 = this.mul32(k1, c2);

      h1 ^= k1;
      h1 = ((h1 & 0x7ffff) << 13) | (h1 >>> 19); // ROTL32(h1,13);
      h1 = (h1 * 5 + 0xe6546b64) | 0;
    }

    if ((len % 2) == 1) {
      k1 = data.charCodeAt(roundedEnd);
      k1 = this.mul32(k1, c1);
      k1 = ((k1 & 0x1ffff) << 15) | (k1 >>> 17); // ROTL32(k1,15);
      k1 = this.mul32(k1, c2);
      h1 ^= k1;
    }

    // finalization
    h1 ^= (len << 1);

    // fmix(h1);
    h1 ^= h1 >>> 16;
    h1 = this.mul32(h1, 0x85ebca6b);
    h1 ^= h1 >>> 13;
    h1 = this.mul32(h1, 0xc2b2ae35);
    h1 ^= h1 >>> 16;

    return h1;
  }
};
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
murmurhash3_gc.js
murmurhash3_32_gc("lol", 1);
ready
murmurhash3.js hashString
MurmurHash3.hashString("lol", 3, 1);
ready
murmurhash3.js hashBytes
MurmurHash3.hashBytes("lol", 3, 1);
ready

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