On Tue, Apr 14, 2009 at 7:18 PM, Kyle Sluder <kyle.slu...@gmail.com> wrote: > On Tue, Apr 14, 2009 at 7:09 PM, Michael Ash <michael....@gmail.com> wrote: >> This is not so. It's extremely rare to find a platform which >> *requires* aligned access, and you certainly won't find one running OS >> X. What's more common is finding a platform which *prefers* aligned >> access, punishing misaligned access with significantly slower >> operation. Even in those cases, "misaligned" means using an address >> that isn't a multiple of your data type's size. Since char is always >> one byte by definition, it is impossible to have a misaligned char >> pointer. > > x64 requires certain alignments: > http://software.intel.com/en-us/articles/data-alignment-when-migrating-to-64-bit-intel-architecture/
That has to be the most confusing technical document I've ever seen. I'm not certain, but after reading it about three times, I'm pretty sure that it's discussing data alignment on IA-64 (Itanium), not x86-64. Microsoft certainly thinks that x86-64 supports unaligned data access, with speed penalties: http://msdn.microsoft.com/en-us/library/aa290049.aspx And a quick test confirms that my Mac Pro, at least, has no trouble reading a misaligned int pointer. Mike _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
