RE: [lwip-users] IP Address Display Functions

[Kieran Mansley]

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