ACB_DATAIN
(acb->flags & ACB_DATAIN) != 0);
acb->flags |= ACB_DATAIN;
if (acb->flags & ACB_DATAIN)
acb->flags |= ACB_DATAIN;
if (acb->flags & ACB_DATAIN)
acb->flags = ACB_ACTIVE | ACB_DATAIN;