xorshift64 RNG implemented in Google Apps Script

xorshift64.gs

function xor(state1, state2) {
	var x = state1.slice()
	x[0] ^= state2[0]
	x[1] ^= state2[1]
	return x
}

/*
state:
[ state[0] ][ state[1] ]
*/

function lshift(state, width) {
	var x = state.slice()
	topBits = state[1] >>> (32 - width)
	x[1] <<= width
	x[0] <<= width
	x[0] |= topBits
	return x
}

function rshift(state, width) {
	var x = state.slice()
	var bot = state[0]
	bot << (32 - width)
	x[0] >>>= width
	x[1] >>>= width
	x[1] &= bot
	return x
}

function randgen(seed1, seed2, iter) {
	var state = [seed1, seed2]
	for (var i = 0; i < iter; i++) {
		var x = state.slice()
		x = xor(x, lshift(x, 13))
		x = xor(x, rshift(x, 7))
		x = xor(x, lshift(x, 17))
		state = x.slice()
	}

	var res = Math.abs(state[0] * Math.pow(2, 32) + state[1])
	return res / 10000
}

/**
 * Generates a random number using the 64-bit XORSHIFT algorithm.
 *
 * @param {number} seed1 The first half of the seed.
 * @param {number} seed2 The second half of the seed.
 * @param {number} iter The iteration or range of iterations.
 * @return The random number.
 * @customfunction
 */
function RANDOMGEN(seed1, seed2, iter) {
  if (iter.length) {
    for (var i = 0; i < iter.length; i++) {
      iter[i] = randgen(seed1, seed2, iter[i])
    }
    return iter
  } else {
    return randgen(seed1, seed2, iter)
  }
}