30 Jan
2014
30 Jan
'14
4:43 p.m.
Jacob Erlbeck wrote:
Remember that N>1 only with very small or very large usec values,
which I guess will be a corner case since it wasn't handled before?
+/* add
sec,usec to tv */
+static void tv_add(struct timeval *tv, int sec, int usec)
+{
+
+ while (usec < 0) {
+ usec += USEC_1S;
+ sec--;
+ }
+ tv->tv_sec += sec;
+ tv->tv_usec += usec;
+ while (tv->tv_usec >= USEC_1S) {
+ tv->tv_sec++;
+ tv->tv_usec -= USEC_1S;
+ }
+}
I'm not sure whether it is a good idea to use while loops in this case
since CPU usage is O(N) of the usec value. Wouldn't it be more convenient to have a function
tv_add_us(tv, usec)
instead that does the div/mod stuff to a temporary timeval and then
just calls timeradd()?
Is there a machine where div/mod is actually more efficient than a
small number of iterations around a loop? :)
Is this a hot path? Then I think it makes sense to optimize harder
for performance rather than for readability. But compilers are good
at that too..
//Peter