int tv_diff(const struct timeval *b, const struct timeval *a, struct timeval *diff);
-long unsigned tv2ms(const struct timeval*);
-void d2tv(double, struct timeval*);
-void tv_add(const struct timeval*, const struct timeval *, struct timeval *);
-void tv_scale(const unsigned long, const struct timeval *, struct timeval *);
-void tv_divide(const unsigned long divisor, const struct timeval *tv,
- struct timeval *result);
-void ms2tv(const long unsigned n, struct timeval *tv);
int64_t get_current_time(void);