lovevanilla/crypto.js

Celebrating the Art of Simplicity in Web Development

export function murmurhash3_32_gc(key, seed = 0) {
  let remainder = key.length & 3; // key.length % 4
  let bytes = key.length - remainder;
  let h1 = seed;
  let k1 = 0;

  for (let i = 0; i < bytes; i += 4) {
    k1 =
      (key.charCodeAt(i) & 0xff) |
      ((key.charCodeAt(i + 1) & 0xff) << 8) |
      ((key.charCodeAt(i + 2) & 0xff) << 16) |
      ((key.charCodeAt(i + 3) & 0xff) << 24);
    k1 = Math.imul(k1, 0xcc9e2d51);
    k1 = (k1 << 15) | (k1 >>> 17);
    k1 = Math.imul(k1, 0x1b873593);
    h1 ^= k1;
    h1 = (h1 << 13) | (h1 >>> 19);
    h1 = Math.imul(h1, 5) + 0xe6546b64;
  }

  k1 = 0;
  switch (remainder) {
    case 3:
      k1 ^= (key.charCodeAt(bytes + 2) & 0xff) << 16;
    case 2:
      k1 ^= (key.charCodeAt(bytes + 1) & 0xff) << 8;
    case 1:
      k1 ^= key.charCodeAt(bytes) & 0xff;
      k1 = Math.imul(k1, 0xcc9e2d51);
      k1 = (k1 << 15) | (k1 >>> 17);
      k1 = Math.imul(k1, 0x1b873593);
      h1 ^= k1;
  }

  h1 ^= key.length;
  h1 ^= h1 >>> 16;
  h1 = Math.imul(h1, 0x85ebca6b);
  h1 ^= h1 >>> 13;
  h1 = Math.imul(h1, 0xc2b2ae35);
  h1 ^= h1 >>> 16;

  return h1 >>> 0;
}