Re: C array to ada record interface

[Jeffrey Carter <spam@spam.com>]

Francisco Javier Loma Daza wrote:

> struct
> {
>    int a,b,c:
>    int len;
>    struct b* arr;
> } A;
> 
> And I would love to interface in Ada with a record with a discriminant
> 
> type B_array(len: Positive) is record
>     arr: array of B(1..len);
> end record;
> 
> type A(len: Positive) is
>    a,b,c: Integer;
>    arr:   A(len);
> end record;

Assuming you meant

    Arr : B_Array (Len => Len);

this won't work. What you have from C is a pointer; the actual array may 
  not even be contiguous with the struct. You'll have to do something like

type B_Ptr is access all B;
pragma Convention (C, B_Ptr);

type A_Info is record
    A, B, C : Interfaces.C.Int;
    Len     : Interfaces.C.Int;
    Arr     : B_Ptr;
end record;
pragma Convention (C, A_Info);

You only use these types when talking directly to C. For the rest of 
your application, you use something like the record you presented, and 
have your operations that talk to C convert between the 2.

-- 
Jeff Carter
"This trial is a travesty. It's a travesty of a mockery of a
sham of a mockery of a travesty of two mockeries of a sham. ...
Do you realize there's not a single homosexual on that jury?"
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