#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <windows.h>

static long long get_win32_time(int)
{
  FILETIME ft;
  GetSystemTimeAsFileTime(&ft);
  LARGE_INTEGER it = { { ft.dwLowDateTime, ft.dwHighDateTime } };
  return it.QuadPart;
}

static long long get_posix_time(int id)
{
  timespec ts;
  if (clock_gettime(id, &ts))
    return -1;
  return ts.tv_sec * 1000000000LL + ts.tv_nsec;
}

static long long get_posix_res(int id)
{
  timespec ts;
  if (clock_getres(id, &ts))
    return -1;
  return ts.tv_sec * 1000000000LL + ts.tv_nsec;
}

static long long guess_resolution(long long (*f)(int), int id = -1)
{
  long long r = ~0ULL>>1;
  for (int i = 0; i < 5; i++) {
    long long t1 = f(id), t2;
    do
      t2 = f(id);
    while (t2 >= 0 && t2 == t1);
    if (t2 - t1 < r)
      r = t2 - t1;
  }
  return r;
}
    
int main(int argc, char **argv)
{
  printf("SystemTime  CLOCK_REALTIME (getres)     CLOCK_MONOTONIC (getres)");
  long long r1 = -1, r2 = -1, r3 = -1;
  int cnt = 0;
  for (;;) {
    long long r1n = guess_resolution(get_win32_time);
    long long r2n = guess_resolution(get_posix_time, CLOCK_REALTIME);
    long long r3n = guess_resolution(get_posix_time, CLOCK_MONOTONIC);

    if (r1 == r1n && r2 == r2n && llabs(r3-r3n) <= 1) {
      printf("%s%5d", (cnt ? "\b\b\b\b\b" : ""), cnt); fflush(stdout);
      sleep(1);
      cnt++;
    }
    else {
      r1 = r1n; r2 = r2n; r3 = r3n;
      printf("\n%.7f   %.9f (%.9f)   %.9f (%.9f)",
        r1/10000000.0,
        r2/1000000000.0, get_posix_res(CLOCK_REALTIME) /1000000000.0,
        r3/1000000000.0, get_posix_res(CLOCK_MONOTONIC)/1000000000.0);
      fflush(stdout);
      cnt = 0;
    }
  }

  return 0;
}