Check the OS version at runtime. If it's Windows 7, use GetSystemTimeAsFileTime . If it's Windows 8+, use the precise version.
// Calculate elapsed 100-ns intervals since init elapsed = (currentCounter.QuadPart - initialCounter.QuadPart) * 10000000; elapsed = elapsed / freq.QuadPart; // Convert to 100-ns units
Because Windows 7 entered extended support and eventually reached End of Life (EOL) without these core kernel modifications, Microsoft never officially backported the API. Consequently, compiling a modern application that depends on this function will result in a runtime error ( Entry Point Not Found ) if run on a standard Windows 7 environment. How to "Patch" or Emulate the Functionality on Windows 7
// Calculate elapsed time in 100-ns units LONGLONG llElapsed = (liCurrentCount.QuadPart - llBasePerformanceCount) * 10000000; llElapsed /= liFrequency.QuadPart; getsystemtimepreciseasfiletime windows 7 patched
Never assume that high-precision APIs are available. Always check at runtime using the techniques described above.
Some users have found success by:
An alternative approach is to check the operating system version at runtime and select the appropriate API accordingly. This method can be simpler to implement but requires careful handling of future Windows versions. Check the OS version at runtime
The core problem is simple: GetSystemTimePreciseAsFileTime does not exist in Windows 7's kernel32.dll . Microsoft's official requirements list:
High-Precision Timestamping on Windows 7
), which is why the newer GetSystemTimePreciseAsFileTime API was designed. // Calculate elapsed 100-ns intervals since init elapsed
For years, Windows developers faced a frustrating gap: no API returned a precise, system time-of-day timestamp. Then came Windows 8 and Server 2012, introducing the hero function: .
Several converging trends have made this error increasingly common:
// Only update baseline periodically to prevent drift uint64_t ft_elapsed = ft_now_raw - ft_base_raw; double qpc_expected = (double)ft_elapsed / 10000000.0 * clock->qpc_frequency.QuadPart;