I was looking into the algorithm a bit, and if you convert it to bitshift operations it boils down to this:
secret = bxor(secret <<< 6, secret) &&& 2 ** 22 - 1
secret = bxor(secret >>> 5, secret) &&& 2 ** 22 - 1
secret = bxor(secret <<< 11, secret) &&& 2 ** 22 - 1
So it shifts left, right, left, XORing with itself and cutting off at 22 bits each time.
I was thinking maybe you could reduce it down to one operation, but the XOR prevents that. Or maybe it doesn’t… 
