Re: Getting modular type size in bits

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Lutz Donnerhacke <lutz@iks-jena.de> writes:

> * Robert A Duff wrote:
> > Jano <402450@cepsz.unizar.es> writes:
> >> I want to know that the type size is 5. I'm aware of the 'modulus 
> >> attribute, and 'size. If I understand correctly, 'size returns the size 
> >> allocated by the compiler for the type (normally 8 in this case), not 
> >> the _minimum_ size to allocate it (which is what I would need in that 
> >> case).
> >
> > 'Size returns the minimum -- i.e. how big it would be if it were a
> > component of a packed record.  That's 32 in this case.  If it were
> > "mod 2**5", then Number'Size would be 5, not 8.
> 
> $ cat t.adb
> with Ada.Text_IO;
> 
> procedure t is
>    type A is mod 2**5;
>    for A'Size use 8;
> begin
>    Ada.Text_IO.Put_Line(Natural'Image(A'Size));
>    declare
>       type B is new A;
>    begin
>       Ada.Text_IO.Put_Line(Natural'Image(B'Size));
>    end;
> end t;
> $ ./t
>  8
>  8
> $ _

So?  You asked for 8, and you got 8.  And it will be (at least) 8 bits
in a packed record.  If you take out the "for A'Size ...", which was not
in the original poster's example, it should be 5.

- Bob