#include <stdio.h>
#include <sys/time.h>


struct timeval tv1, tv2, stv, etv;
struct timezone tz;

void
waitTime(int time) {
   (void) gettimeofday(&tv1, &tz);
   while (1) {
   (void) gettimeofday(&tv2, &tz);
   if ((tv2.tv_sec-tv1.tv_sec)*1000000+(tv2.tv_usec-tv1.tv_usec)- time>=-4) 
      break;
   } 
}

main() {
   int time, diff;
   int i, j, counter, counter2;
   int min, max;
   double avg;
   for (i=10; i<=1000000; i=i*10) {
    counter=0; counter2=0; min=6; max=0; avg=0.0;
    for (j=0; j<1000; j++) {

     (void) gettimeofday(&stv, &tz);
     waitTime(i);
     (void) gettimeofday(&etv, &tz);
     diff= (etv.tv_sec-stv.tv_sec)*1000000+(etv.tv_usec-stv.tv_usec);

     if (diff -i > 6) {
        printf("wait %dusec, diff=%dusec, stv=%d.%d, etv=%d.%d\n", 
                i, diff, stv.tv_sec, stv.tv_usec, etv.tv_sec, etv.tv_usec) ;
        counter++;
        time = diff -i;
        if (min > time) min=time;
        if (max < time) max=time;
        avg+=time; 
     } 
     if (diff -i <-5) {
        printf("diff less: wait %dusec, diff=%dusec, stv=%d.%d, etv=%d.%d\n", 
                i, diff, stv.tv_sec, stv.tv_usec, etv.tv_sec, etv.tv_usec) ;
        counter2++;
     }
    }
    avg /= counter;
    printf("for %dusec, j=%dtimes, error>6 counter=%d, error<-5 counter2=%d\n", 
           i, j, counter, counter2);
    printf("    min=%d, max=%d, avg=%f\n", min, max, avg);
   }
}