Path: utzoo!mnetor!uunet!husc6!mit-eddie!uw-beaver!cornell!batcomputer!pyramid!decwrl!cookie.dec.com!devine
From: devine@cookie.dec.com (Bob Devine)
Newsgroups: comp.lang.c
Subject: Re:  what C needs -- packed structures
Message-ID: <8801071842.AA04669@decwrl.dec.com>
Date: 7 Jan 88 18:42:24 GMT
Organization: Digital Equipment Corporation
Lines: 27

Path: decwrl!labrea!rutgers!cmcl2!brl-adm!brl-smoke!gwyn
Subject: Re: what C needs
 
I wrote:
>When writing code that requires control of alignment or location,
> [...I want a way to pack a structure]
 
Doug Gwyn wrote:
> If you're under the impression that a simple, efficient mechanism
> exists or could feasibly be made to exist for "rolling in" raw binary
> data obtained from another system, you're sadly mistaken.

  No, I didn't want a full-blown XDR or presentation layer type of
function.  What I described was smaller.  I stemmed from an experience
where two vendor's compilers where used on the same architecture but
with different layouts of data.  Frustrating!

  A different argument for providing packed/unpacked structures is
simply to allow the programmer to choose between access speed or
smaller data segment.  As an example of prior art, Microsoft C has
a compile time flag for this.  Granted, not all structures would
be packed the same way or even could be packed.  Some architectures
allow ints to be only integer aligned (pyramid, I believe) while
others all ints to be char aligned (vax).

  Consider this suggestion in light of the C philosophy or letting
the programmer decide.