Interfacing to C: big structures

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:

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-****table
(how to get the "appropriate size"?).

Would you suggest some other solution?

--
Maciej Sobczak * www.msobczak.com * www.inspirel.com