Re: IO, ANSI vs GCC structs

[Wolfgang Denk <wd@denx.de>]

In message <Pine.LNX.4.44.0307251038370.22864-100000@spider.ancor.com> you wrote:
>
> > Does GCC make guarantees beyond what ANSI requires?  Is there some
> > subtle detail that forces struct layout ("volatile" in the definition
> > perhaps)?
>
> There is nothing that guarentees this, in ANSI or GCC.

You can use "__attribute__ ((packed))" with GCC which  guaratees  you
control  over  the  alignment  used  by the compiler (it will use the
smallest possible alignment = one byte for a variable,  and  one  bit
for  a  field,  unless  you specify a larger value with the `aligned'
attribute).


Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
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