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From: sullivan@marge.math.binghamton.edu (fred sullivan)
Newsgroups: comp.lang.modula2
Subject: Re: Bit shifting operations
Message-ID: <669@bingvaxu.cc.binghamton.edu>
Date: Wed, 26-Aug-87 16:35:41 EDT
Article-I.D.: bingvaxu.669
Posted: Wed Aug 26 16:35:41 1987
Date-Received: Fri, 28-Aug-87 06:30:27 EDT
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Reply-To: sullivan@marge.math.binghamton.edu (fred sullivan)
Organization: Department of Mathematical Sciences, SUNY-Binghamton
Lines: 21

>Supposedly, Modula-2 is a good systems programming language; but it
>has no native bit-shifting operations.  Aren't bit-shifting 
>operations important tools for EFFICIENT systems programming?
>Turbo Pascal and "C" have native bit-shifting operations, but not
>Modula-2.  Was this omission a wise design decision?  I would like
>to read some opinions on this question.

I agree that I sometimes wish that they existed.  On the other hand, bit
operations are inherently machine dependent.  Since such things are
going to vary from machine to machine anyway, perhaps Prof. Wirth decided
that it should be up to Modula implementors for various machines to include
shifts or not.  At least one compiler (the Powell compiler for Ultrix)
includes a bit manipulation module which implements shifts as in-line code
(although they appear to the user to be procedures).  At any rate, most
things (e.g. setting up masks) can be done effiently with Intsets anyway.

Fred Sullivan
Department of Mathematical Sciences
State University of New York at Binghamton
Binghamton, New York  13903
Email: sullivan@marge.math.binghamton.edu