gettimeofday implementaiton for windows

win-gettimeofday.c

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

#if defined(_MSC_VER) || defined(_MSC_EXTENSIONS)
  #define DELTA_EPOCH_IN_MICROSECS  11644473600000000Ui64
#else
  #define DELTA_EPOCH_IN_MICROSECS  11644473600000000ULL
#endif

struct timezone 
{
  int  tz_minuteswest; /* minutes W of Greenwich */
  int  tz_dsttime;     /* type of dst correction */
};

int gettimeofday(struct timeval *tv, struct timezone *tz)
{
  FILETIME ft;
  unsigned __int64 tmpres = 0;
  static int tzflag = 0;

  if (NULL != tv)
  {
    GetSystemTimeAsFileTime(&ft);

    tmpres |= ft.dwHighDateTime;
    tmpres <<= 32;
    tmpres |= ft.dwLowDateTime;

    tmpres /= 10;  /*convert into microseconds*/
    /*converting file time to unix epoch*/
    tmpres -= DELTA_EPOCH_IN_MICROSECS; 
    tv->tv_sec = (long)(tmpres / 1000000UL);
    tv->tv_usec = (long)(tmpres % 1000000UL);
  }

  if (NULL != tz)
  {
    if (!tzflag)
    {
      _tzset();
      tzflag++;
    }
    tz->tz_minuteswest = _timezone / 60;
    tz->tz_dsttime = _daylight;
  }

  return 0;
}

#define TEST
#ifdef TEST
int main()
{
  struct timeval now; 
  struct timezone tzone;

  gettimeofday(&now, NULL);
  gettimeofday(&now, &tzone);
}
#endif