How can I replicate the functionality of `clock_gettime` on Windows systems when porting code from POSIX environments?

Porting clock_gettime to Windows

The clock_gettime function is a POSIX function that returns the current time. It is not available on Windows, so a replacement function is needed when porting code from a POSIX system to Windows.

One possible replacement function for clock_gettime on Windows is the GetSystemTimeAsFileTime function. This function returns the current time as a FILETIME structure. The FILETIME structure is a 64-bit integer that represents the number of 100-nanosecond intervals since January 1, 1601.

To use the GetSystemTimeAsFileTime function to replace clock_gettime, the following code can be used:

<code class="c++">#include <windows.h>

int clock_gettime(int X, struct timeval *tv)
{
    FILETIME ft;
    GetSystemTimeAsFileTime(&ft);
    tv->tv_sec = ft.dwHighDateTime;
    tv->tv_usec = ft.dwLowDateTime / 10;
    return 0;
}</windows.h></code>

This code will return the current time in the tv structure. The tv_sec field will contain the number of seconds since January 1, 1970, and the tv_usec field will contain the number of microseconds since the last second.

Another possible replacement function for clock_gettime on Windows is the QueryPerformanceCounter function. This function returns the current time as a LARGE_INTEGER structure. The LARGE_INTEGER structure is a 64-bit integer that represents the number of 100-nanosecond intervals since the computer was started.

To use the QueryPerformanceCounter function to replace clock_gettime, the following code can be used:

<code class="c++">#include <windows.h>

int clock_gettime(int X, struct timeval *tv)
{
    LARGE_INTEGER ft;
    QueryPerformanceCounter(&ft);
    tv->tv_sec = ft.QuadPart / 10000000;
    tv->tv_usec = ft.QuadPart % 10000000 / 10;
    return 0;
}</windows.h></code>

This code will return the current time in the tv structure. The tv_sec field will contain the number of seconds since the computer was started, and the tv_usec field will contain the number of microseconds since the last second.

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