Re: Interfacing to C: big structures

["Steve" <nospam_steved94@comcast.net>]

"Maciej Sobczak" <see.my.homepage@gmail.com> wrote in message 
news:c48dc7da-6f04-4f0f-9a8f-e0acc371ee3c@o10g2000hsf.googlegroups.com...
> Hi,
>
> Consider the C API that contains some structure S and a couple of
> functions that operate on the state that is stored in the Struct. A
> typical usage in C might be:
>
> struct S s;
>
> init(&s);
> foo(&s);
> bar(&s);
> baz(&s);
>
> Above, s is created with automatic storage duration.
>
> How to interface to this from Ada? I see two options:

I don't understand what you mean by "How to interface to this from Ada?":

  Do you want to be able to perform additional operations on struct S using 
Ada code?

    swizzle(&s);

  Where "swizzle" is an Ada procedure?

  Or are you asking for something different?

Regards,
Steve
(The Duck)

>
> 1. Write a simple wrapper that will create S on the heap and use the
> pointer everywhere. This is easy, but imposes the use of dynamic
> memory, which for some reasons I might want to avoid.
> 2. Create an Ada array of basic storage units of "appropriate size"
> and pass its address to the C functions. The advantage of this
> solution is that it does not impose any particular memory management
> scheme, but the disadvantage is that it is potentially non-portable
> (how to get the "appropriate size"?).
>
> Would you suggest some other solution?
>
> --
> Maciej Sobczak * www.msobczak.com * www.inspirel.com