index.js

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;
}

module.exports = murmurhash3_32_gc;