Date: Sat, 30 Jan 1999 10:06:18 -0500 (EST) From: Brian Feldman <green@unixhelp.org> To: Nik Clayton <nik@nothing-going-on.demon.co.uk> Cc: Greg Lehey <grog@lemis.com>, Garrett Wollman <wollman@khavrinen.lcs.mit.edu>, chat@FreeBSD.ORG Subject: Re: You are not expected to understand this (was: btokup().. patch to STYLE(9) (fwd)) Message-ID: <Pine.BSF.4.05.9901300959500.28645-100000@janus.syracuse.net> In-Reply-To: <19990130090229.A19159@catkin.nothing-going-on.org>
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On Sat, 30 Jan 1999, Nik Clayton wrote:
> On Sat, Jan 30, 1999 at 10:57:42AM +1030, Greg Lehey wrote:
> > > The comment was actually ``You are not expected to understand this'',
> > > and it was in v7's swtch().
> >
> > Almost. From the Sixth Edition, /usr/sys/ken/slp.c, the end of
> > swtch():
>
> <snip>
>
> FWIW, there's a similar comment in sys/i386/boot/biosboot/io.c and
> sys/pci/ncr.c.
What am I not expected to understand about the one in io.c? tw_chars is most
likely ('|' | '/' << 8 | '-' << 16 | '\\' << 24) (I sure hope I got operator
precedence right, if not, then tw_chars is int = *(int *)"|/-\\").
tw_chars = (tw_chars >> 8) | ((tw_chars & (unsigned long)0xFF) << 24);
would simply change tw_chars from "|/-\\" to "/-\\|" and so on. I think that
someone made too much out of this to be quoting Ken.
>
> I have memories of a particularly hairy piece of code somewhere in the
> time/date libraries, with the comment "You are expected not to understand
> this", but I can't find it now.
>
> N
> --
> Bagel: The carbohydrate with the hole
>
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