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Mail Archives: djgpp/1997/02/27/11:52:32

Date: Thu, 27 Feb 1997 05:37:12 +0000 ( )
From: "Gurunandan R. Bhat" <grbhat AT unigoa DOT ernet DOT in>
To: "John M. Aldrich" <fighteer AT cs DOT com>
Cc: djgpp AT delorie DOT com
Subject: Re: some advice required
In-Reply-To: <3315B014.3C8C@cs.com>
Message-Id: <Pine.LNX.3.91.970227053400.2975A-100000@aditya.unigoa.ernet.in>
Mime-Version: 1.0


On Thu, 27 Feb 1997, John M. Aldrich wrote:

> Gurunandan R. Bhat wrote:
> > 
> > greetings,
> >         will a kind assembly guru pick this nit please: assuming that x+y
> > and x|y give me the same result, which one is faster?
> 
> The logical OR is probably much faster, but those two are NOT equivalent
> unless x and y have no bits in common!  

yes, thats precisely what i have. in my app (optimised fft actually), x 
and y have no bits in common.  

> If you can _guarantee_ that,
> then the OR is one of the fastest machine insructions there is.  :)

thanks.

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