time_constant
tc = time_constant(hz); \
/*((prescaler - 1) << 16) |*/ (time_constant(stathz)));
static long time_constant; /* poll interval (shift) (s) */
time_constant = 0;
time_constant = MAXTC;
time_constant = ntv->constant;
ntv->constant = time_constant;
L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);