OFFBTS
bno = (atl >> OFFBTS) & BLKMSK;
*bp = ((tline >> OFFBTS) & BLKMSK);
bno = (maxt >> OFFBTS) & BLKMSK;
maxt = ((bno << OFFBTS) | (cnt >> SHFT)) & ~1;
bno = (atl >> OFFBTS) & BLKMSK;