Lpc2000

Dave,

Think about whet your saying here:

> ip = (int *)&buf[5];
> 
> should be treated by the compiler as:
> 
> ip = (__packed int *)&buf[5];
> 

"should" doesn't come into it! You have explicitley told the 
compiler exectly how you want it treated (the "(int *)"). Now if you 
had one of those magic "do what I mean, not what I say" compilers, 
you'd be fine......

By the way, if you find that compiler, let me know!

Brendan

--- In lpc2000@yahoogroups.com, "dsidlauskas1" <dsidlauskas@...> 
wrote:
>
> Jaya,
> 
> I don't think I'm asking it to connect the two statements.
> 
> What I'm expecting it to do is to recognize that buf is a byte 
packed
> object (the defalt for the compler)and when casting byte packed
> objects the compiler should cast them to other byte packed objects.
> 
> in otherwords;
> 
> char buf[10];
> int ip*;
> 
> ip = (int *)&buf[5];
> 
> should be treated by the compiler as:
> 
> ip = (__packed int *)&buf[5];
> 
> and this is because char buf[10] is a byte packed object for this
> compiler.
> 
> Dave
> 
> 
> --- In lpc2000@yahoogroups.com, "jayasooriah" <jayasooriah@> wrote:
> >
> > Dave,
> > 
> > I think what you are asking of the compiler is to connect the two
> > statements in the for() loop.  Compilers do not have this 
capability.
> >  Even if it did, it would have to also consider the for() 
statement
> > too, as your code would be legitimate if the for() statement was:
> > 
> > >  for (i = 0; i < ...; i += 4)
> > 
> > A purist would argue is that there is nothing wrong with the 
pointer
> > assignment given the explicit cast.  The error occurs only if 
(and
> > when) the pointer is dereferenced at runtime.
> > 
> > Making it a packed array on these grounds may not be what the
> > programmer intended.  Besides, packed array methods involve
> > implementation issues.
> > 
> > GCC was kind enough to allude you to the possibility of such an 
event
> > ocurring.  Note that it too did not make the relationship 
between the
> > two statements.  If it did, it would report an error, not a 
warning.
> > 
> > Jaya
> > 
> > --- In lpc2000@yahoogroups.com, "dsidlauskas1" <dsidlauskas@> 
wrote:
> > >
> > > Jaya,
> > > 
> > > Since the compiler knows that buf is a byte aligned object, 
woutldn't
> > > it be resonable for the compiler to treat
> > > 
> > > (int *)&buf[i]
> > > 
> > > as 
> > > 
> > > (__packed int *)&buf[i]
> > > 
> > > In general, if non-naturaly aligned objects are promoted by a 
cast,
> > > shouldn't, by default, the cast be of the proper non-aligned 
type?
> > > 
> > > BTW. Really appreciate your discussion of interupts on your 
web site.
> > > 
> > > Dave
> >
>