Re: Waiver question

[Corey Minyard <minyard@acm.org>]

Laurent Guerby <Laurent.Guerby@enst-bretagne.fr> writes:

> 
> Corey Minyard <minyard@acm.org> writes:
> > [...] For instance, the following code (and I hope
> > the kind readers of the newsgroup excuse me for using C, but it is
> > more compact for this type of stuff):
> 
>    Sacrilege ! See below. ;-)
> 
> > int
> > main()
> > {
> >    int a[4];
> >    char *c;
> > 
> >    a[0] = 0; a[1] = 0; a[2] = 0; a[3] = 0;
> >    c = (char *) a;
> >    c[0] = 0x01;
> >    c[1] = 0x02;
> >    c[2] = 0x03;
> >    c[3] = 0x04;
> >    printf("%x %x %x %x\n", a[0], a[1], a[2], a[3]);
> >    return 0;
> > }
> 
>    Here a somewhat equivalent Ada code, people can judge the
> "compactness": 
> 
> with Ada.Text_IO;         use Ada.Text_IO;
> with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
> with Interfaces;          use Interfaces;
> procedure Main is
>    A : array (1..4) of Integer   := (others => 0);
>    C : array (1..4) of Integer_8 := (1, 2, 3, 4);   
>    for C'Address use A'Address;
> begin
>    Put (A (1), 12, 16);   Put (A (2), 12, 16);
>    Put (A (3), 12, 16);   Put (A (4), 12, 16);
>    New_Line;
> end Main;           

I stand corrected.  I actually don't know Ada that well and had
forgotten about what the "for" statement can do.  However, I could
have made the C just as compact, it just would have been harder to
read.

> 
>    Of course in Ada the "with" clauses are mandatory (not the case of
> #include in C. If you want to use the C printf, you can also do it, it
> removes a few Ada IO with clauses:
> 
> procedure printf (Fmt : String; A, B, C, D : Integer);
> pragma Import (C, printf);
> ...
> printf ("%x %x %x %x" & ASCII.LF, A (1), A (2), A (3), A (4));
> 
> > on the Alpha will print:
> > 	1020304 0 0 0
> > and on the C40 will print:
> > 	1 2 3 4
> > because on the C40 a char and an int are the same size because the
> > minimum size of any addressable unit is 32-bits.
> 
>    On Intel/Linux/GNAT I get
> 
>  16#4030201#       16#0#       16#0#       16#0# 
> 
>    or
> 
> 4030201 0 0 0

This is correct for Intel since it is little endian.

-- 
Corey Minyard               Internet:  minyard@acm.org
  Work: minyard@nortel.ca       UUCP:  minyard@wf-rch.cirr.com