Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!killer!texbell!uhnix1!sugar!ficc!peter
From: peter@ficc.uu.net (Peter da Silva)
Newsgroups: comp.arch
Subject: Re: Endian wars
Message-ID: <3057@ficc.uu.net>
Date: 9 Feb 89 23:32:47 GMT
References: <6133@columbia.edu> <3300050@m.cs.uiuc.edu>
Organization: Xenix Support
Lines: 30

In article <3300050@m.cs.uiuc.edu>, gillies@m.cs.uiuc.edu writes:
> while (*p++ = *q++);

p, q in registers:

	tst  (rq)
	beq  pool
loop:	movb (rq)+,(rp)+
	bne loop
pool:

> len = *p++ = *q++;
> while(len-->0)
>	*p++ = *q++;

	movb (rq)+,rtemp
	movb rtemp,(rp)+
	beq pool
loop:	movb (rq)+,(rp)+
	sob rtemp,loop	; not at all sure of the syntax here
pool:

Two instructions for the loop, either way. But the former is more likely
to be implemented by a dumb compiler... what did Ritchie's compiler do
for it with p and q in registers?
-- 
Peter da Silva, Xenix Support, Ferranti International Controls Corporation.
Work: uunet.uu.net!ficc!peter, peter@ficc.uu.net, +1 713 274 5180.   `-_-'
Home: bigtex!texbell!sugar!peter, peter@sugar.uu.net.                 'U`
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