On Mon, 29 Dec 2008, John Emmas wrote: > Yesterday I spent some time looking into this but didn't come to any > hard & fast conclusions. Variables themselves seem to correlate very well > between MSVC and Cygwin (even 'long' which I thought was different). But > when calculating structure alignment (manually) sometimes Cygwin gave > closer results to what I expected and sometime MSVC was closer.
The only major difference I'm aware of is that Cygwin defaults to 8 byte alignment for long long and double for performance reasons, while MSVC defaults to 4 byte alignment for those types I believe. > Before I try Ralph's suggestion I'd like (if possible) to try building both > versions with struct packing disabled. This is fairly simple to do with > Microsoft's compiler (I just set the member alignment to '1 byte') but can > it be done for my Cygwin compiler - e.g. with a compiler option or a #pragma > or whatever? Google attribute packed as I don't remember the exact syntax, but I fail to see how this actually helps your cause. -- Brian Ford Staff Realtime Software Engineer VITAL - Visual Simulation Systems FlightSafety International the best safety device in any aircraft is a well-trained crew... -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
