clock_gettime2_win32.c

int clock_gettime(int, struct timespec *tv)
{
    LARGE_INTEGER curCount;
    static int initialized = 0;
    static LARGE_INTEGER freq, startCount;
    static struct timespec tv_start;
    time_t sec_part;
    long nsec_part;

    if (!initialized) {
        FILETIME filetime;
        __int64 temp;
        QueryPerformanceFrequency(&freq);
        QueryPerformanceCounter(&startCount);
        GetSystemTimeAsFileTime(&filetime);
        temp = filetime.dwHighDateTime;
        temp <<= 32;
        temp |= filetime.dwLowDateTime;
        temp -= 116444736000000000ULL;
        tv_start.tv_sec = temp / 10000000UL;
        tv_start.tv_nsec = (temp % 10000000UL) * 100;
        initialized = 1;
    }

    QueryPerformanceCounter(&curCount);

    curCount.QuadPart -= startCount.QuadPart;
    sec_part = curCount.QuadPart / freq.QuadPart;
    nsec_part = (long)((curCount.QuadPart - (sec_part * freq.QuadPart))
            * 1000000000UL / freq.QuadPart);

    tv->tv_sec = tv_start.tv_sec + sec_part;
    tv->tv_nsec = tv_start.tv_nsec + nsec_part;
    if(tv->tv_nsec >= 1000000000UL) {
        tv->tv_sec += 1;
        tv->tv_nsec -= 1000000000UL;
    }
    return 0;
}