#define _GNU_SOURCE 1
#include <time.h>
#include <sys/time.h>
#include <stdio.h>
#include <signal.h>
#include <stdlib.h>

struct timeval max, avg;
long numsamples;

void interrupt(int sig)
{
	avg.tv_sec /= numsamples;
	avg.tv_usec /= numsamples;
	
	printf("max diff %ld.%ld avgdiff %ld.%ld numsamples %lu\n", 
	       max.tv_sec, max.tv_usec,
	       avg.tv_sec, avg.tv_usec,
	       numsamples);
	exit(0);
}

void statistics(struct timeval *diff)
{
	if (timercmp(diff, &max, >))
		max = *diff;
	timeradd(diff, &avg, &avg);
	numsamples++;
}

int main(void)
{
	static struct timespec onesec = { .tv_sec = 1 }; 
	struct timespec rem = {};
	struct timeval last, now, diff;

	printf("Press Ctrl-c to stop\n");
	signal(SIGINT, interrupt);
	gettimeofday(&last, NULL);
	for (;;) {
		nanosleep(&onesec, &rem);
		if (rem.tv_sec + rem.tv_nsec > 0)
			printf("remainder %ld.%ld\n", rem.tv_sec, rem.tv_nsec/1000);
		gettimeofday(&now, NULL);
		timersub(&now, &last, &diff);
		statistics(&diff);
		printf("%ld.%ld\n", diff.tv_sec, diff.tv_usec);
		last = now;		
	}
	return 0;
}