윈도우에서 gettimeofday 함수구현 - windows gettimeofday function

< 상대시간 >

int gettimeofday(struct timeval* tp, int* tz)
{
LARGE_INTEGER tickNow;
static LARGE_INTEGER tickFrequency;
static BOOL tickFrequencySet = FALSE;
if (tickFrequencySet == FALSE) {
QueryPerformanceFrequency(&tickFrequency);
tickFrequencySet = TRUE;
}
QueryPerformanceCounter(&tickNow);
tp->tv_sec = (long) (tickNow.QuadPart / tickFrequency.QuadPart);
tp->tv_usec = (long) (((tickNow.QuadPart % tickFrequency.QuadPart) * 1000000L) / tickFrequency.QuadPart);

return 0;
}

< 절대시간 - unix 타임 >

#include <stdio.h>
#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;
uint64_t tmpres = 0;
static int tzflag;

if (NULL != tv)
{
// system time을 구하기
GetSystemTimeAsFileTime(&ft);

// unsigned 64 bit로 만들기
tmpres |= ft.dwHighDateTime;
tmpres <<= 32;
tmpres |= ft.dwLowDateTime;

// 100nano를 1micro로 변환하기
tmpres /= 10;

// epoch time으로 변환하기
tmpres -= DELTA_EPOCH_IN_MICROSECS;  

// sec와 micorsec으로 맞추기
tv->tv_sec = (tmpres / 1000000UL);
tv->tv_usec = (tmpres % 1000000UL);
}

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

return 0;
}

int64_t GetTimeOfDay()
{
struct timeval now;
GetTimeOfDay(&now, NULL);

int64_t millisecond = (int64_t)(now.tv_sec)*1000 + (int64_t)(now.tv_usec)/1000;

return millisecond;
}