RING_FRAC
#define RING_FRAC(ap) ((int)RING_CNT(ap) >= (int)(RINGSIZE/RINGFRAC))
#define RING_FRAC(zap) ((int)RING_CNT(zap) >= (int)(RINGSIZE/RINGFRAC))
#define RING_FRAC(ap) ((int)RING_CNT(ap) >= (int)(RINGSIZE/RINGFRAC))