Re: Problem using Ada.Text_IO.Modular_IO

[jujosei@googlemail.com]

On Jul 9, 11:50 pm, Adam Beneschan <a...@irvine.com> wrote:
> On Jul 9, 9:52 am, jujo...@googlemail.com wrote:
>
>
>
> > Dear All,
>
> > I'm tying to print variables of a defined modular type to the standard
> > io and a file.
> > The type I'm working with is: type Unsigned is mod 2**64;
>
> > Therefore I define a modular_io package to do this:
> > package mio is new ada.text_io.modular_io(usigned);
>
> > However, when compile my little test program (using gnatmake -gnato),
> > the compiler tells me that a "Constraint Error" will be raised at
> > runtime. So I tried it with only 63 bit (mod 2**63), which works fine
> > with the GNAT 4.3.1 (20080420) on a 32bit Ubuntu-Linux machine.
>
> > ----------- test program -----------
> > with ada.text_io; use ada.text_io;
> > procedure test is
> >         type Unsigned is mod 2**64;
> >         package M_IO is new Ada.Text_IO.Modular_IO (Unsigned);
> >         u : Unsigned := -1;
> > begin
> >         m_io.put(Item =>  u, Width =>  20, Base  => 16);
> > end;
> > -----------------------------------------
>
> > I guess that this is a bug. However, what can I do instead of this, to
> > get 64 bit words printed as hex, octal and binary?
>
> Here's an even simpler workaround than my last suggestion: After the
> declaration of "u", just add this:
>
>   pragma Volatile (u);
>
> This prevents the compiler from thinking it knows what "u" is going to
> hold, and everything works fine.  Of course, in real-life code, you're
> a lot more likely to using "put" on a value that the compiler won't be
> able to determine at compile time, so the above bug isn't going to
> appear anyway and you don't need a workaround.
>
>                                -- Adam

Thank you Adam,
pragma Volatile (u); is perfect!

Cheers

Julian