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#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/limits.h>
#include <sys/time.h>
#include <time.h>
#include <errno.h>
#include <string.h>
long long nanotime(void)
{
struct timespec t;
if(clock_gettime(CLOCK_MONOTONIC, &t)) {
fprintf(stderr,"clock failure\n");
exit(1);
}
return (((long long) t.tv_sec) * 1000000000LL) +
((long long) t.tv_nsec);
}
static struct timespec ts_sub(struct timespec a, struct timespec b)
{
struct timespec r;
r.tv_sec = a.tv_sec - b.tv_sec;
r.tv_nsec = a.tv_nsec - b.tv_nsec;
if(r.tv_nsec < 0) {
r.tv_sec--;
r.tv_nsec += 1000 * 1000 * 1000;
}
if(r.tv_sec < 0 && r.tv_nsec > 0) {
r.tv_sec++;
r.tv_nsec -= 1000 * 1000 * 1000;
}
return r;
}
static struct timespec ts_min(struct timespec a, struct timespec b)
{
if(a.tv_sec < b.tv_sec || (a.tv_sec == b.tv_sec && a.tv_nsec < b.tv_nsec))
return a;
else
return b;
}
static struct timespec ts_max(struct timespec a, struct timespec b)
{
if(a.tv_sec < b.tv_sec || (a.tv_sec == b.tv_sec && a.tv_nsec < b.tv_nsec))
return b;
else
return a;
}
int main(int argc, char **argv)
{
long long tnow, tlast;
struct timespec t1, dtmin, dtminp, dtmax;
int print_interval = 50000;
int print_countdown = 1;
int clock_id = CLOCK_MONOTONIC;
dtmin.tv_sec = INT_MAX;
dtmin.tv_nsec = 0;
dtminp.tv_sec = INT_MAX;
dtminp.tv_nsec = 0;
dtmax.tv_sec = 0;
dtmax.tv_nsec = 0;
tlast = 0;
if(argc == 2) {
clock_id = atoi(argv[1]);
printf("using clock %d\n", clock_id);
}
clock_gettime(clock_id, &t1);
for(;;) {
struct timespec t, dt;
clock_gettime(clock_id, &t);
dt = ts_sub(t, t1);
t1 = t;
dtmin = ts_min(dtmin, dt);
if(dt.tv_sec > 0 || dt.tv_nsec > 0)
dtminp = ts_min(dtminp, dt);
if(print_countdown != print_interval)
dtmax = ts_max(dtmax, dt);
if(--print_countdown == 0) {
fprintf(stderr,"%09ld.%09ld, dt %ld.%09ld, min %ld.%09ld, minp %ld.%09ld, max %ld.%09ld\n",
t.tv_sec, t.tv_nsec, dt.tv_sec, dt.tv_nsec,
dtmin.tv_sec, dtmin.tv_nsec, dtminp.tv_sec, dtminp.tv_nsec,
dtmax.tv_sec, dtmax.tv_nsec);
print_countdown = print_interval;
}
}
for(;;) {
tnow = nanotime();
if(tnow < tlast) {
#if 0
fprintf(stderr,"time went backwards: %lld -> %lld\n",
tlast, tnow);
exit(1);
#endif
fprintf(stderr,"%lld ROLLBACK\n", tnow);
} else {
fprintf(stderr,"%lld\n", tnow);
}
tlast = tnow;
}
return 0;
}
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