N2RNG_REGISTERED
#define n2rng_setregistered(n2rng) ((n2rng)->n_flags |= N2RNG_REGISTERED)
#define n2rng_clrregistered(n2rng) ((n2rng)->n_flags &= ~N2RNG_REGISTERED)
#define n2rng_isregistered(n2rng) ((n2rng)->n_flags & N2RNG_REGISTERED)