From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: f849b,869d7890f1bd9878
X-Google-Attributes: gidf849b,public
X-Google-Thread: 103376,869d7890f1bd9878
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2003-02-18 02:39:23 PST
Path: 
 archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.icl.net!newsfeed.fjserv.net!newsfeed.freenet.de!news.rwth-aachen.de!!broeker
From: Hans-Bernhard Broeker <broeker@physik.rwth-aachen.de>
Newsgroups: comp.lang.ada,comp.arch.embedded
Subject: Re: Type-safe low-level programming?
Date: 18 Feb 2003 10:39:22 GMT
Organization: Aachen University of Technology (RWTH)
Message-ID: <b2t2gq$650$1@nets3.rz.RWTH-Aachen.DE>
References: <cbdd91ae.0302171606.57d2ba77@posting.google.com>
NNTP-Posting-Host: acp3bf.physik.rwth-aachen.de
X-Trace: nets3.rz.RWTH-Aachen.DE 1045564762 6304 137.226.32.75 (18 Feb 2003
 10:39:22 GMT)
X-Complaints-To: abuse@rwth-aachen.de
NNTP-Posting-Date: 18 Feb 2003 10:39:22 GMT
Originator: broeker@
Xref: archiver1.google.com comp.lang.ada:34190 comp.arch.embedded:59709
Date: 2003-02-18T10:39:22+00:00
List-Id: <comp.lang.ada>

In comp.arch.embedded Bernd Trog <berndtrog@yahoo.com> wrote:

> Now I wonder, if its possible to make 'Set_Bit' type-safe *without*
> increasing the program memory size for every new register?

The only way I see is to drop the idea of passing the register and the
bit number inside that register as independent parameters --- they
aren't independent, and pretending they are is what causes your grief.
The need to introduce a comment to explain what Bit_A1 is supposed to
mean should have given you the hint.

What you need would be more like

  type Bit_Number is range 0 .. 8*16#ff#);

  Register_A : constant Address_Type := 1;

  Bit_A1 : constant Bit_Number := Register_A*8 + 4; 
  Bit_A2 : constant Bit_Number := Register_A*8 + 1;
[...]

and then

	procedure Set_Bit(Nr : in Bit_Number );

which would split up the Bit_Number in two parts, one to address a
register, the other to address bits inside that register.

Disclaimer: the above are the first lines of Ada code I ever edited in
my life, so don't trust them any further than you can throw your car
;-)
-- 
Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.