SCALE_USEC
ltemp = ((time_offset / mtemp) * (SCALE_USEC /
SCALE_USEC) / SCALE_KF)
bigtick = (int)usec_per_tick * SCALE_USEC;
u_usec = usec * SCALE_USEC;
time_maxerror += time_tolerance / SCALE_USEC;
time_adj += (lltemp * SCALE_PHASE) / (SCALE_USEC * hz);
#define MAXFREQ (512 * SCALE_USEC) /* max freq error (100 ppm) */