Re: Interfacing to C without dynamic memory

[Maciej Sobczak <see.my.homepage@gmail.com>]

On 15 Lis, 12:52, Samuel Tardieu <s...@rfc1149.net> wrote:

> Note that you can also do it at run time, even if it costs a few more
> cycles to allocate the object, by taking advantage of C ability to
> resolve "sizeof" into a static value at compile time. This obliviates
> the cross-compilation issues.

> const size_t T_size = sizeof(struct T);

>    T_Size : constant Interfaces.C.size_t;
>    pragma Import (C, T_Size, "T_size");

Neat. This possibility was not obvious to me.

>    type Opaque_T is new Interfaces.C.char_array (1 .. T_Size);
>    for Opaque_T'Alignment use 8;

Of course, I can similarly extract the magic 8 constant from the C
file (sizeof(long long) or such).

Two more questions:

1. Any technical difference between System.Storage_Array and
Interfaces.C.char_array? Considering that the target module is C,
using the latter is more logical, but apart from "name affinity" is
there anything that can make a difference in practice?

2. Now the array has run-time size instead of compile-time size (as
you mentioned yourself). Is there any difference, especially in terms
of memory management? Are such arrays guaranteed to be allocated on
the stack?

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

Database Access Library for Ada: www.inspirel.com/soci-ada