timercmp?

Five macros for manipulating time values are defined in <sys/time.h>:

timerclear(struct timeval *)
Sets a time value to zero.

timerisset(struct timeval *)

Tests if a time value is non-zero.

timercmp(struct timeval *a, struct timeval *b, CMP)
Compares two time values in the form a CMP b, where CMP is <, =, or
> (beware that >= and <= do not work with this macro).

timersub(struct timeval *a, struct timeval *b, struct timeval *res)
Subtracts a - b and stores the result in res.

timeradd(struct timeval *a, struct timeval *a, struct timeval *res)
Adds two timers and stores the result in res.