function XorShift(seed) {
  if (!Array.isArray(seed) || seed.length !== 4) {
    throw TypeError('seed must be an array with 4 numbers');
  }

  // uint64_t s = [seed ...]
  this.state0U = seed[0] | 0;
  this.state0L = seed[1] | 0;
  this.state1U = seed[2] | 0;
  this.state1L = seed[3] | 0;
}
Create a pseudorandom number generator, with a seed.

@param {Array} seed "128-bit" integer, composed of 4x32-bit
integers in big endian order.