Re: Urgent question: malloc and ada...

[Jonathan Guthrie <jguthrie@brokersys.com>]

In comp.lang.ada Richard Kenner <kenner@lab.ultra.nyu.edu> wrote:
> >Actually, I was commenting more on the alignment of structs (which, as
> >far as I know, can vary even on those systems with a single calling
> >convention) than the calling convention.  Calling conventions are usually
> >reasonably well standardized, the alignment of structs is not.  Yet your 
> >post implied that both are covered (as they would have to be) by the
> >requirements.

> On most modern systems, details of how structures are supposed to be aligned
> are discussed in the same document that discusses the calling sequence.

<snippage>

> I see no difference between the two issues.

On many systems, the calling convention is carved in stone.  Unfortunately,
on every C compiler that I know well, it is possible to adjust the
alignment of the fields in structs on a case-by-case basis.  Those alignments
do not have to correspond to any system convention or even make any 
sense.  Of course, most of the compilers I know well are for Intel
processors, but it's in the GCC documentation.  In fact GNU C allows a
lot more leeway in how you specify the alignment of the fields in a struct
than the MS-DOS/Windows compilers I've used.

I, for one, am a lot more likely to muck about with the struct alignment
than I am to attempt to change the calling convention.

In any case, that sounds pretty different to me.  The statement has been
made that the Ada compiler is required to deal with all the complexities
of the Ada/C interface, I'm just trying to probe the limits and find out
what they are.

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Jonathan Guthrie (jguthrie@brokersys.com)
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