Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!airs!ian
From: ian@airs.com (Ian Lance Taylor)
Newsgroups: comp.compression
Subject: Re: Standard: Memory problems continued.
Keywords: proposed data compression standard memory
Message-ID: <1930@airs.com>
Date: 22 Jun 91 15:21:08 GMT
References: <872@spam.ua.oz>
Sender: news@airs.com
Lines: 37

ross@spam.ua.oz.au (Ross Williams) writes:

>OK OK I'm being a martinet again.  Agreed. The standard has to be more
>flexible  than I  have made  it about  where memory  comes from.  I am
>getting uneasy about how the standard is loosening up though. I wanted
>to  place a  bound  on the  stack so  that  procedures wouldn't  cause
>trouble on machines with a small stack space (e.g. some microprocessor
>embedded systems).

Your standard seems to be driving at two different goals at once:

    1) Allow programs to use several different compression subroutines.

    2) Require compression subroutines to be portable between
       machines.

The point you are making above seems to relate only to goal 2.  I
think the real benefit of the standard will be goal 1.  It's going to
be awfully hard to make all compression routines portable to all
machines anyhow.  That seems to me to be, as the C language standard
would say, a ``quality of implementation'' issue for the compression
routine itself.  Furthermore, an implementation on a machine with lots
of stack space could use the stack; an implementation on a machine
without stack space could use some other memory.  There shouldn't be a
requirement that the same compression code work on different machines;
only that if a different machine is supported, the same functionality
is provided.

Allowing programs to use different compression routines with a
standard interface seems to me to be a worthy goal.  Specifying
details about where the memory comes from seems needlessly machine
specific.
-- 
Ian Taylor                   ian@airs.com                 uunet!airs!ian
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