The structure layouts of LARGE_INTEGER and FILETIME are such that it is safe to cast them to and from a 64-bit integer — ws_sint64_t (defined to be signed __int64 for Borland, Digital Mars, Visual C++ and Watcom compilers, and signed long long for Comeau, GCC, and Metrowerks compilers) — so long as the platform is little-endian (i.e., Intel), since the LowPart/dwLowDateTime member preceeds the HighPart/dwHighDateTime member. I do not have access to the Win32 headers for any big-endian systems (i.e., PowerPC, ALPHA), so I cannot presume that the layout of the structure members would be reversed (although I hope they would be), which would maintain the compatibility with the 64-bit integers. If they are not, then the systemtime_counter, highperformance_counter, threadtimes_ counter, processtimes_counter, and highperformance_ counter classes are not valid for systems that are not little-endian.
— M.W.