AW: Static vs dynamic evaluation anomaly?

AW: Static vs dynamic evaluation anomaly?

[Grein, Christoph (Fa. ESG)]

Silly me, I meant

with Ada.Text_IO;
use  Ada.Text_IO;
procedure test271 is
  type Six_Bits is mod 2**6;
  X: constant Six_Bits := 31;
  Z: constant Integer  := 31;
begin
  for J in 0..5 loop
    Put_Line (Integer 'Image         (J) &
              Six_Bits'Image  (X * 2**J) &
              Integer 'Image ((Z * 2**J) mod Six_Bits'Modulus));
  end loop;
end test271;
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Re: Static vs dynamic evaluation anomaly?

[Adam Beneschan]

On Feb 6, 9:29 am, Matt Jaffe <jaf...@cableone.net> wrote:

> Any further help in explaining these anomalies would be much appreciated.  (It's always possible we've stumbled across a compiler bug; but I am reluctant to come to that conclusion prematurely.)

I'm not so reluctant.  It's a compiler bug.

The following program produces incorrect results on GNAT, or at least
on the version I'm using:

with Ada.Text_IO;
procedure test271 is
    type Six_Bits is mod 2**6;
    package Six_Bit_IO is new Ada.Text_IO.Modular_IO(Six_Bits);
    X : Six_Bits := 31;
begin
    for J in 0..5 loop
        Ada.Text_IO.Put ("When J=" & Integer'image(J));
        Ada.Text_IO.Put (", X*2**J =");
        Six_Bit_IO.Put(X*2**J);
        Ada.Text_IO.New_Line;
    end loop;
end test271;

                      -- Adam

AW: Static vs dynamic evaluation anomaly?

[Grein, Christoph (Fa. ESG)]

No, this program is absolute correct. Modular types do not overflow,
they use modular arithmetic.

with Ada.Text_IO;
use  Ada.Text_IO;
procedure test271 is
  type Six_Bits is mod 2**6;
  X: constant Six_Bits := 31;
  Z: constant Integer  := 31;
begin
  for J in 0..5 loop
    Put_Line (Integer 'Image         (J) &
              Six_Bits'Image  (X * 2**J) &
              Integer 'Image ((X * 2**J) mod Six_Bit'Modulus));
  end loop;
end test271;

Re: AW: Static vs dynamic evaluation anomaly?

[Stefan Lucks]

There seems to be something wrong with the Put_Line statement:

On Wed, 7 Feb 2007, Grein, Christoph (Fa. ESG) wrote:

> with Ada.Text_IO;
> use  Ada.Text_IO;
> procedure test271 is
>   type Six_Bits is mod 2**6;
>   X: constant Six_Bits := 31;
>   Z: constant Integer  := 31;
> begin
>   for J in 0..5 loop
>     Put_Line (Integer 'Image         (J) &
>               Six_Bits'Image  (X * 2**J) &
>               Integer 'Image ((X * 2**J) mod Six_Bit'Modulus));
    Put_Line (Integer 'Image         (J) &
              Six_Bits'Image  (X * 2**J) &
              Integer 'Image ((Integer(X) * 2**Integer(J))
                                mod Six_Bits'Modulus)
             );
>   end loop;
> end test271;
>

-- 
Stefan Lucks      Th. Informatik, Univ. Mannheim, 68131 Mannheim, Germany
            e-mail: lucks@th.informatik.uni-mannheim.de
            home: http://th.informatik.uni-mannheim.de/people/lucks/
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