<div class="gmail_quote">2011/9/20 Lionel Elie Mamane <<a href="mailto:lionel@mamane.lu">lionel@mamane.lu</a>> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"> <div class="im">On Mon, Sep 12, 2011 at 10:45:31PM +0200, CaStarCo wrote: > @Lionel , What is the QuadPart member of the structure? The high > part? the low part? or another thing? </div>The union is fully described at <a href="http://msdn.microsoft.com/en-us/library/aa383713%28v=vs.85%29.aspx" target="_blank">http://msdn.microsoft.com/en-us/library/aa383713(v=vs.85).aspx</a> Are you familiar with the concept of C/C++ union? If not, Google gives a few hits that don't seem too bad at first sight: </blockquote><div> Ok, thanks! :) I know the concept of union, my problem was the definition of "QuadPart". </div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> <a href="http://www.cplusplus.com/doc/tutorial/other_data_types/#union" target="_blank">http://www.cplusplus.com/doc/tutorial/other_data_types/#union</a> <a href="http://www.go4expert.com/forums/showthread.php?t=15" target="_blank">http://www.go4expert.com/forums/showthread.php?t=15</a> <a href="http://en.wikipedia.org/wiki/Union_%28computer_science%29" target="_blank">http://en.wikipedia.org/wiki/Union_(computer_science)</a> <a href="http://msdn.microsoft.com/en-us/library/y9zewe0d%28v=vs.80%29.aspx" target="_blank">http://msdn.microsoft.com/en-us/library/y9zewe0d(v=vs.80).aspx</a> To get to your question, the QuadPart is the whole 64 bits, that is the combination of the high part *and* the low part. Essentially, the paragraph I quoted says that to treat the FILETIME value as a 64bit integer, one should proceed as such: __int64 Value; FILETIME *ft = // some value ULARGE_INTEGER t; t.LowPart = ft->dwLowDateTime; t.HighPart = ft->dwHighDateTime; // Now, t.QuadPart contains the right 64 bits integer Value = t.QuadPart; // or use t.QuadPart directly instead of Value instead of: Value = *(__int64*)ft; </blockquote><div> It's true, using unions is clearer and cleaner than using forced type castings. </div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> Do not hesitate to CC to me any additional question you have on this matter. <div><div></div><div class="h5"> > 2011/9/12 Lionel Elie Mamane <<a href="mailto:lionel@mamane.lu">lionel@mamane.lu</a>> >> On Sun, Sep 11, 2011 at 10:04:52PM +0200, CaStarCo wrote: >>> I've created a second (very little too) patch to reduce the scope of a >>> variable. >>> --- a/sal/osl/w32/file_dirvol.cxx >>> +++ b/sal/osl/w32/file_dirvol.cxx >>> @@ -60,7 +60,6 @@ extern "C" BOOL TimeValueToFileTime(const TimeValue *cpTimeVal, FILETIME *pFTime >> Thank you for your contribution to LibreOffice, it is most >> welcome. Looking at that function in that file, it needs a more >> thorough cleanup, and maybe other functions in that file and/or in >> other files in the same directory; see >> <a href="http://msdn.microsoft.com/en-us/library/ms724284%28v=VS.85%29.aspx" target="_blank">http://msdn.microsoft.com/en-us/library/ms724284%28v=VS.85%29.aspx</a>, in >> particular: >> It is not recommended that you add and subtract values from the >> FILETIME structure to obtain relative times. Instead, you should copy >> the low- and high-order parts of the file time to a ULARGE_INTEGER >> structure, perform 64-bit arithmetic on the QuadPart member, and copy >> the LowPart and HighPart members into the FILETIME structure. >> Do not cast a pointer to a FILETIME structure to either a >> ULARGE_INTEGER* or __int64* value because it can cause alignment >> faults on 64-bit Windows. >> It would be best to look at every place that FILETIME is used in that >> directory. >> Just in case you want to volunteer for that cleanup :) >> When you send a patch, could you please confirm the patch is licensed >> under MPL1.1/LGPLv3+? To make things easier, you can do a one-time >> blanket "all my patches" thing if you wish, sort of common to do that. </div></div>-- Lionel </blockquote></div>