Re: How to put 200 into an integer sub-type of 16 bits (code included)

[Ludovic Brenta <ludovic@ludovic-brenta.org>]

ChristopherL wrote on comp.lang.ada:
> What I want to do is this. I have a variable holding the base 10 value
> 200. It has a certain bit representation. If the variable was an
> integer of 16 bits it's representation would be something such as
> 0000000011001000. For give me if I'm wrong. Anyway, what I'd like to
> do is put that exact bit representation in another variable of a
> different type.
>
> How do I proceed?

The way to do it is with Unchecked_Conversion, as your example shows.
Beware, however, that interpreting the bit representation in another
type will probably yield a different value.

   Size_Of_Float : constant := Float'Size;
   type Modular_Type_With_Same_Size_As_Float is mod 2 **
Size_Of_Float;
   for Modular_Type_With_Same_Size_As_Float'Size use Float'Size;
   Two_Hundred : constant Modular_Type_With_Same_Size_As_Float := 200;
   function To_Float is new Ada.Unchecked_Conversion
(Modular_Type_With_Same_Size_As_Float, Float);
   F : constant Float := To_Float (Two_Hundred);

You can substitute any type you want for Float. The bit representation
of F will be the same as the bit representation of Two_Hundred, but
the value of F is *not* going to be 200.  It is even possible that the
bit pattern is illegal for a Float (or your chosen type); you would
then get a Constraint_Error. Is that what you want?

--
Ludovic Brenta.