ring_full_count
#define NETBYTES() (ring_full_count(&netoring))
#define TTYBYTES() (ring_full_count(&ttyoring))
ring_full_count (Ring *ring),
netout = ring_full_count(&netoring) &&
ttyout = ring_full_count(&ttyoring);
if (ring_full_count(&ttyiring)) {
if (ring_full_count(&netiring)) {
n0 = ring_full_count(&ttyoring);
} while (ring_full_count(&netiring)); /* While there is any */