How to Port `clock_gettime()` to Windows for Precise Timekeeping?

Porting clock_gettime to Windows

The clock_gettime() function is a POSIX system call that provides high-precision timing information. When porting code from QNX to Windows, it is necessary to implement a replacement for clock_gettime() in order to maintain accurate timekeeping.

Windows Implementation

To implement a clock_gettime() replacement for Windows, the following steps can be taken:

1. Define a LARGE_INTEGER structure to store the time offset:

<code class="c++">LARGE_INTEGER
getFILETIMEoffset()
{
    // ... Implementation omitted for brevity
}</code>

2. Implement the clock_gettime() function:

<code class="c++">int
clock_gettime(int X, struct timeval *tv)
{
    // ... Implementation omitted for brevity
}</code>

This implementation uses the Windows QueryPerformanceCounter() function to obtain high-precision timing information. If QueryPerformanceCounter() is not available, the GetSystemTimeAsFileTime() function can be used instead. The frequencyToMicroseconds variable is calculated to convert the timer frequency to microseconds.

By following these steps, you can implement a clock_gettime() replacement for Windows that provides accurate and consistent timing information.

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