移植clock_gettime到Windows [英] Porting clock_gettime to windows

问题描述

我对QNX momemntics运行以下code。

I have the following code running on qnx momemntics.

#define BILLION 1000000000L;

struct timespec start_time;
struct timespec stop_time; 

void start MyTestFunc() {
    //Initialize the Test Start time
     clock_gettime(CLOCK_REALTIME,&start_time)
    // ... additonal code.

    cout << "The exectuion time of func "<< calculateExecutionTime();
}


double calculateExecutionTime ()
{

    clock_gettime(CLOCK_REALTIME,&stop_time);

    double dSeconds = (stop_time.tv_sec - start_time.tv_sec);

    double dNanoSeconds = (double)( stop_time.tv_nsec - start_time.tv_nsec ) / BILLION;

    return dSeconds + dNanoSeconds;
}

现在我想上面code到Windows端口。任何一个可以提供样品code。

Now i want to port above code to windows. can any one provide sample code.

谢谢！

推荐答案

您可以实现一个Windows clock_gettime（）的替代如下：

You can implement a clock_gettime() replacement for windows as follows:

LARGE_INTEGER
getFILETIMEoffset()
{
    SYSTEMTIME s;
    FILETIME f;
    LARGE_INTEGER t;

    s.wYear = 1970;
    s.wMonth = 1;
    s.wDay = 1;
    s.wHour = 0;
    s.wMinute = 0;
    s.wSecond = 0;
    s.wMilliseconds = 0;
    SystemTimeToFileTime(&s, &f);
    t.QuadPart = f.dwHighDateTime;
    t.QuadPart <<= 32;
    t.QuadPart |= f.dwLowDateTime;
    return (t);
}

int
clock_gettime(int X, struct timeval *tv)
{
    LARGE_INTEGER           t;
    FILETIME            f;
    double                  microseconds;
    static LARGE_INTEGER    offset;
    static double           frequencyToMicroseconds;
    static int              initialized = 0;
    static BOOL             usePerformanceCounter = 0;

    if (!initialized) {
        LARGE_INTEGER performanceFrequency;
        initialized = 1;
        usePerformanceCounter = QueryPerformanceFrequency(&performanceFrequency);
        if (usePerformanceCounter) {
            QueryPerformanceCounter(&offset);
            frequencyToMicroseconds = (double)performanceFrequency.QuadPart / 1000000.;
        } else {
            offset = getFILETIMEoffset();
            frequencyToMicroseconds = 10.;
        }
    }
    if (usePerformanceCounter) QueryPerformanceCounter(&t);
    else {
        GetSystemTimeAsFileTime(&f);
        t.QuadPart = f.dwHighDateTime;
        t.QuadPart <<= 32;
        t.QuadPart |= f.dwLowDateTime;
    }

    t.QuadPart -= offset.QuadPart;
    microseconds = (double)t.QuadPart / frequencyToMicroseconds;
    t.QuadPart = microseconds;
    tv->tv_sec = t.QuadPart / 1000000;
    tv->tv_usec = t.QuadPart % 1000000;
    return (0);
}

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