} while(0)
#define ao_fifo_full(f) ((((f).insert + 1) & (AO_FIFO_SIZE-1)) == (f).remove)
+#define ao_fifo_mostly(f) ((((f).insert - (f).remove) & (AO_FIFO_SIZE-1)) >= (AO_FIFO_SIZE * 3 / 4))
+#define ao_fifo_barely(f) ((((f).insert - (f).remove) & (AO_FIFO_SIZE-1)) >= (AO_FIFO_SIZE * 1 / 4))
#define ao_fifo_empty(f) ((f).insert == (f).remove)
#if PACKET_HAS_MASTER || PACKET_HAS_SLAVE