Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!mit-eddie!minya!jc
From: jc@minya.UUCP (John Chambers)
Newsgroups: comp.unix.programmer
Subject: Re: wanted: information on Duff's Device -
Message-ID: <445@minya.UUCP>
Date: 8 Jan 91 02:14:05 GMT
References: <1990Dec24.034911.17074@decuac.dec.com> <1990Dec25.135417.27999@news.cs.indiana.edu>
Lines: 78


	[History of "Duff's Device"]

> 	send(to, from, count)
> 	register short *to, *from;
> 	register count;
> 	{
> 		register n=(count+7)/8;
> 		switch(count%8){
> 		case 0:	do{	*to = *from++;
> 		case 7:		*to = *from++;
> 		case 6:		*to = *from++;
> 		case 5:		*to = *from++;
> 		case 4:		*to = *from++;
> 		case 3:		*to = *from++;
> 		case 2:		*to = *from++;
> 		case 1:		*to = *from++;
> 			}while(--n>0);
> 		}
> 	}
> 
> Disgusting, no?  But it compiles and runs just fine.  I feel a combination
> of pride and revulsion at this discovery.  If no one's thought of it before,
> I think I'll name it after myself.

Uh, why is this disgusting?  It strikes me as simple and elegant.  I have
severe doubts that any minimally-competent C programm would have even the
slightest trouble understanding it.  It's not tricky, convoluted, confusing,
or anything else negative.  So why would someone object to it?

Myself, I think that people object to simple, elegant things just because
they are simple and elegant [but I don't claim to read minds. ;-]

What I was hoping for was a simple, elegant solution that involved a goto.
Now THAT would offend people!  Oh, well, maybe next time.

Of course, I would have put the while before the loop, but then, I'm rather
paranoid.  For n==0, the above code will copy 8 bytes, which could cause a
SEG fault, and guess whose routine dbx/sbd/whatever would finger?

































[To satisfy the line count daemon.]
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