linux-kernel - Re: [RFC PATCH] consolidate within() implementations

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Date:	Tue, 3 Jun 2008 11:08:28 +0200
From:	Mikael Pettersson <mikpe@...uu.se>
To:	Peter Oberparleiter <peter.oberparleiter@...ibm.com>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Harvey Harrison <harvey.harrison@...il.com>,
	Peter Oberparleiter <oberparleiter@...glemail.com>
Subject: Re: [RFC PATCH] consolidate within() implementations

Peter Oberparleiter writes:
 > +static inline int addr_within_len(const void *addr, const void *start,
 > +				  size_t len)
 > +{
 > +	return ((unsigned long) addr >= (unsigned long) start) &&
 > +	       ((unsigned long) addr < ((unsigned long) start + len));
 > +}

On most machines you'd get better code with

	return (unsigned long)((char*)addr - (char*)start) < (unsigned long)len;

Maybe a candidate for a follow-up optimisation patch?
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