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From: adam@miduet.UUCP
Newsgroups: comp.arch,comp.lang.c
Subject: Re: String Handling -- Incompetence of run-time libraries
Message-ID: <531@gec-mi-at.co.uk>
Date: Fri, 10-Apr-87 04:43:48 EST
Article-I.D.: gec-mi-a.531
Posted: Fri Apr 10 04:43:48 1987
Date-Received: Wed, 15-Apr-87 00:48:53 EST
References: <15292@amdcad.UUCP> <978@ames.UUCP> <15694@sun.uucp>
Reply-To: adam@gec-mi-at.co.uk (Adam Quantrill)
Organization: Marconi Instruments Ltd., St. Albans, Herts, UK
Lines: 35
Keywords: instruction set architectures, strcpy
Xref: utgpu comp.arch:854 comp.lang.c:1592

In article <9996@sri-spam.istc.sri.com> robert@sri-spam.UUCP (Robert Allen) writes:
>
>To further speed this up you could write it as:
>
>	strcpy2(ss1,ss2)
>	register char *ss1, *ss2;
>	{
>	    while (*s1++ = *s2++)
>	    ;
>	}
>
>thus eliminating two assignments and two local variables.
>
If your machine doesn't complain at char-int alignment, try

strcmp2(s1, s2)
register short int *s1, *s2;
{
	while (*s1 == *s2++)
		if (!((*s1++ & 255) && (*(char *)s1)))
			return(0);
	return(*s1 - *--s2);
}

This relies on the fact that it doesn't matter if you compare the NULLs at the
end of two equal strings or not. We go along the string twice as fast because
of the 16 bit operations, although there is a slight penalty due to the extra
test. The alignment problem only comes in if either of 
the strings begins on an odd boundary, which is fairly unusual anyway. 
Also watch the last part of the 'if' condition - this won't work on 
some machines, you may have to add 1 to the pointer.
-- 
       -Adam.

/* If at first it don't compile, kludge, kludge again.*/