Re: bitwise comparators

["Matthew Heaney" <matthew_heaney@acm.org>]

In article <3880D375.7E363123@hotmail.com> , Alexander Van Hecke 
<alexke@hotmail.com>  wrote:

> I want to do the following :
> OK_to_proceed : BOOLEAN := FALSE;
> data : Unsigned_8;
>
> while (not OK_to_proceed) loop
>     -- do stuff
>     OK_to_proceed := (data BITWISE AND 2#1#);
> end loop;
>
> so I want to exit the loop if bit one of data is set, but I don't know
> what the bitwise and is!

The bitwise and for modular types is "and".

Don't use the while form of loop; your version requires mental
gymnastics to figure out.  If you want to "exit the loop if bit one of
data is set," then say that directly:

loop
  -- do stuff
  exit when (data and 2#1#) > 0;
end loop;

You also have to be careful what you mean by "bit one".  Are you
referring to the bit that corresponds to the value of 2**0, or 2**1?
Your original example uses 2#1#, which I would probably describe as the
"bit zero."

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