1 #include <stdio.h> 2 #include <unistd.h> 3 #include <sys/time.h> 4 #include <stdint.h> 5 6 int wait_a_while(useconds_t interval)7wait_a_while (useconds_t interval) 8 { 9 int num_times = 0; 10 int return_value = 1; 11 12 struct timeval start_time; 13 gettimeofday(&start_time, NULL); 14 uint64_t target = start_time.tv_sec * 1000000 + start_time.tv_usec + interval; 15 16 while (1) 17 { 18 num_times++; 19 return_value = usleep (interval); 20 if (return_value != 0) 21 { 22 struct timeval now; 23 gettimeofday(&now, NULL); 24 interval = target - now.tv_sec * 1000000 + now.tv_usec; 25 } 26 else 27 break; 28 } 29 return num_times; 30 } 31 32 int main(int argc,char ** argv)33main (int argc, char **argv) 34 { 35 printf ("stop here in main.\n"); 36 int num_times = wait_a_while (argc * 1000); 37 printf ("Done, took %d times.\n", num_times); 38 39 return 0; 40 41 } 42