Path: utzoo!utgpu!tmsoft!tslanpar!woods
From: woods@tslanpar.UUCP (Greg A. Woods )
Newsgroups: comp.lang.c
Subject: Re:  what C needs -- packed structures
Summary: This should read "What C does NOT need."!
Keywords: structures pack data layout
Message-ID: <83@tslanpar.UUCP>
Date: 26 Jan 88 00:30:19 GMT
References: <8801071842.AA04669@decwrl.dec.com>
Reply-To: woods@tslanpar.UUCP ( -Greg A. Woods- )
Distribution: world
Organization: G. A. W. Consulting
Lines: 21


I'm sorry, but a compile time flag is far from what could solve problems with
imposing structure on external data.  Just how do you expect to compile a
module that must load data into a packed structure on one line, and then
perform an ioctl() call on the next to work?  (Most kernel's and device
drivers won't use packed structures!)  How are you to prevent an unknowing
programmer from doing such a thing?  The "-pack" option of the Microsoft
family of C compilers (yes it's still there in Xenix) was a quick and dirty
fix for Lattice's mistake of packing structures in the first place (it wastes
a lot of CPU time in may implementations).

The only possible solution could be the pseudo-functions: pack() and unpack()
ala Pascal.

I personally have had no problems with bit/byte wise manipulation of external
data (using bitfields and unsigned character arrays).
-- 
						Greg Woods.

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