Re: Efficient Matrix?

[Bill Findlay <yaldnifw@blueyonder.co.uk>]

On 28/12/02 17:25, in article BA338F12.1700%yaldnifw@blueyonder.co.uk, "Bill
Findlay" <yaldnifw@blueyonder.co.uk> wrote:

> procedure bla is
> 
>  type unconstrained_type is
>       array (Positive range <>, Positive range <>) of Boolean;
>  for unconstrained_type'Component_Size use 1;
>  pragma Pack (unconstrained_type);
>  type unconstrained_type_ptr is access unconstrained_type;
> 
>  subtype constrained_type is unconstrained_type (1 .. 1000, 1 .. 500);
>  type constrained_type_ptr is access constrained_type;
> 
>  C : constrained_type_ptr   := new constrained_type;
>  U : unconstrained_type_ptr := new unconstrained_type
>                                    (1 .. 1000, 1 .. 500);
> 
...

Well I had a closer look and found this:
        li r6,0
        ori r3,r6,62500
                  ^^^^^ = 1000*500 / 8
        bl L___gnat_malloc$stub
        stw r3,1556(r1)

        li r7,0
        ori r3,r7,62516
                  ^^^^^ = 1000*500 / 8 + 16 (for dope vector?)
        bl L___gnat_malloc$stub
...
So it looks as though the component size and packing are honoured, but the
attributes are lying about it

-- 
Bill-Findlay chez blue-yonder.co.uk ("-" => "")