divers/c/time-measuring.c

57 lines
1.1 KiB
C

#include <stdio.h>
//#include <sys/time.h>
#include <time.h>
#include <stdlib.h>
#define BILLION 1000000000L
#define MILLION 1000000L
#define THOUSAND 1000L
void get_time_ts(struct timespec *t0) {
if (clock_gettime(CLOCK_REALTIME, t0) == -1) {
perror("clock_gettime");
exit(1);
}
}
long long duration_ns(struct timespec t0, struct timespec t1) {
return ((t1.tv_sec - t0.tv_sec)*BILLION) + (t1.tv_nsec - t0.tv_nsec);
}
void print_time_ns(long long time) {
printf("%llds %lldms %lldµ %lldns\n"
, time/BILLION
, (time/MILLION)%THOUSAND
, (time/THOUSAND)%THOUSAND
, time%THOUSAND
);
}
int main (int argc, char** argv) {
struct timespec t0, t1;
get_time_ts(&t0);
int i = 0;
while (i < 10000) { i++; }
get_time_ts(&t1);
long long time = duration_ns(t0, t1);
print_time_ns(time);
return 0;
}
/* // For limited precision: timeval structure + gettimeofday function.
struct timeval t0, t1;
gettimeofday (&t0, NULL);
int i = 0;
while (i < 10000) { i++; }
gettimeofday (&t1, NULL);
printf("%ld ms\n", (t1.tv_sec - t0.tv_sec)*BILLION + (t1.tv_usec - t0.tv_usec));
*/