murmur332.js

/**
 * Performs Murmur3_32 hashing.
 * https://en.wikipedia.org/wiki/MurmurHash
 * @param key Int32Array input key
 * @param seed int32 input seed
 * @returns int32 value
 */
export default function murmur332(key, seed) {
  let hash = seed;

  /* eslint-disable no-bitwise */
  for (let i = 0; i < key.length; i += 1) {
    let k = key[i];
    k = Math.imul(k, -862048943);
    k = (k << 15) | (k >>> 17);
    k = Math.imul(k, 461845907);
    hash ^= k;
    hash = (hash << 13) | (hash >>> 19);
    hash = (Math.imul(hash, 5) + -430675100) | 0;
  }

  hash ^= (key.length << 2);
  hash ^= (hash >>> 16);
  hash = Math.imul(hash, -2048144789);
  hash ^= (hash >>> 13);
  hash = Math.imul(hash, -1028477387);
  hash ^= (hash >>> 16);
  /* eslint-enable no-bitwise */

  return hash;
}