🚀 go-pugleaf

MODULE Demo;

VAR     a, b, c: CARDINAL;

BEGIN
  IF SIZE(CARDINAL) <> SIZE(BITSET) THEN        (* Paranoid? Me?        *)
    UserBreak
  END;
  c:= CARDINAL(BITSET(a) / BITSET(b))
END Demo.

Mark Morgan Lloyd
mark_tbu@cix.compulink.co.uk

[Opinions above are the author's, not those of his employers or 
colleagues]

In article <1996Feb8.114044.15072@ucl.ac.uk> Chris Austin,
zcaccau@cs.ucl.ac.uk writes:
>Is there an XOR function in Topspeed Modula-2 V3.something.  I want to be
>able to XOR either 2 cardinals or 2 BITSETs, so if there isn't a function,
>what is the best way to implement it.  I need speed, not simplicity, as this
>is for graphics routines.
>

I just yesterday needed that to create a XOR checksum required for the
Windows "placeable" Meta-file header!

Low-level tricks like that can be done using SET operations. XOR is "/"
which means for A, B and C CARDINALs:

  "C = A XOR B" <=> C := CARDINAL( BITSET(A) / BITSET(B) );

Check out the "TopSpeed Language Tutorial" on SETs in case I remembered
it wrong. TopSpeed also has a "bitwise boolean operator" pragma that
sometimes
can be handy but which of course is nonportable.

.......................................................................
Bengt-Inge Dalenback
at:                                     and:
   Department of Applied Acoustics         CATT
   Chalmers University of Technology       (Software for room acoustic 
   Gothenburg, SWEDEN                      prediction and auralization)
   e-mail: bid@ta.chalmers.se              e-mail: catt@netg.se

In article: <4fn5qu$ejm@nyheter.chalmers.se>  Bengt-Inge Dalenback <bid@ta.chalmers.se> writes:
> Path: 
demon.co.uk!news.demon.co.uk!demon!tank.news.pipex.net!pipex!news.mathworks.com!news.kei.com!nntp.coast.net!news00.sunet.se!
sunic!news99.sunet.se!news.chalmers.se!g0-mac7.ta.chalmers.se!bid
> From: Bengt-Inge Dalenback <bid@ta.chalmers.se>
> Newsgroups: comp.lang.modula2
> Subject: Re: XOR function
> Date: 12 Feb 1996 10:46:54 GMT
> Organization: CATT & Dep. of Applied Acoustics, Chalmers
> Lines: 28
> Distribution: world
> Message-ID: <4fn5qu$ejm@nyheter.chalmers.se>
> References: <1996Feb8.114044.15072@ucl.ac.uk>
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> X-Newsreader: Nuntius 2.0.1_68K
> X-XXMessage-ID: <AD44D99ED401B84A@g0-mac7.ta.chalmers.se>
> X-XXDate: Mon, 12 Feb 1996 10:48:46 GMT
> 
> In article <1996Feb8.114044.15072@ucl.ac.uk> Chris Austin,
> zcaccau@cs.ucl.ac.uk writes:
> >Is there an XOR function in Topspeed Modula-2 V3.something.  I want to be
> >able to XOR either 2 cardinals or 2 BITSETs, so if there isn't a function,
> >what is the best way to implement it.  I need speed, not simplicity, as this
> >is for graphics routines.
> >
> 
> I just yesterday needed that to create a XOR checksum required for the
> Windows "placeable" Meta-file header!
> 
> Low-level tricks like that can be done using SET operations. XOR is "/"
> which means for A, B and C CARDINALs:
> 
>   "C = A XOR B" <=> C := CARDINAL( BITSET(A) / BITSET(B) );
> 
> Check out the "TopSpeed Language Tutorial" on SETs in case I remembered
> it wrong. TopSpeed also has a "bitwise boolean operator" pragma that
> sometimes
> can be handy but which of course is nonportable.
> 

It may also me much quicker to use the assembly language routine. 
You could use the Visual Debuger to view the asam code and see
which is the quickest. XOR as a machine instrction between to 
16 bit registers is about 2 clock cycles.

-- 
-----------------------------*------------------------------------
Rupert Toncic                |   BCM RTC, London, WC1N 3XX, UK.
Rupert@bcmrtc.demon.co.uk    |      Voice +44 956 275 144
-----------------------------*------------------------------------

In article <533335858wnr@bcmrtc.demon.co.uk>
           Rupert@bcmrtc.demon.co.uk "Rupert Toncic" writes:

> In article: <4fn5qu$ejm@nyheter.chalmers.se>  Bengt-Inge Dalenback
>  <bid@ta.chalmers.se> writes:

> > Low-level tricks like that can be done using SET operations. XOR is "/"
> > which means for A, B and C CARDINALs:
> > 
> >   "C = A XOR B" <=> C := CARDINAL( BITSET(A) / BITSET(B) );
> > 
> > Check out the "TopSpeed Language Tutorial" on SETs in case I remembered
> > it wrong. TopSpeed also has a "bitwise boolean operator" pragma that
> > sometimes
> > can be handy but which of course is nonportable.
> 
> It may also me much quicker to use the assembly language routine. 
> You could use the Visual Debuger to view the asam code and see
> which is the quickest. XOR as a machine instrction between to 
> 16 bit registers is about 2 clock cycles.

At least on the JPI compiler all bitset operations compile to the
appropriate 80x86 instructions so no need to use ASM for this.
I have always been very impressed with their code generator.

IIR Logitech compiler was a bit weak in this area.
(It may have improved recently I no longer use it)

Regards,
-- 
Martin Brown  <martin@nezumi.demon.co.uk>     __                CIS: 71651,470
Scientific Software Consultancy             /^,,)__/