On Tue, 2009-08-25 at 14:01 -0400, Bill Auerbach wrote: > >> Why can't we have a single "packed" attribute at the end of the struct > >>instead of using it each time at the field level? > > > >Different compilers have different syntaxes for declaring packing. That > >is why we have the PACK_STRUCT_STRUCT and PACK_STRUCT_FIELD macros. > > Also, I see a *huge* difference in performance with packing by 2 versus 1 > which we do in many if not all ports.
I find it interesting that this makes a difference. If both work, then the structures must be suitably packed in both cases. If there is a performance difference then the compiler must be accessing the fields differently I suppose. I.e. it sounds to me like your compiler is reading more into packed directives than it needs to (perhaps to make things simpler for it): it is affecting both the packing of the structure and the way it accesses the fields in that structure. Kieran _______________________________________________ lwip-users mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/lwip-users
