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