Path: utzoo!attcan!uunet!husc6!mailrus!ames!oliveb!sun!smile!alanf
From: alanf%smile@Sun.COM (Alan Fargusson)
Newsgroups: comp.lang.c
Subject: Re: Shifting question
Message-ID: <60670@sun.uucp>
Date: 20 Jul 88 18:43:35 GMT
References: <705@bnr-rsc.UUCP> <11556@steinmetz.ge.com> <60290@sun.uucp> <1818@spar.SPAR.SLB.COM>
Sender: news@sun.uucp
Lines: 18

In article <1818@spar.SPAR.SLB.COM>, hunt@spar.SPAR.SLB.COM (Neil Hunt) writes:
> 	rshift = count > 0 ? count : 0;
> 	lshift = count < 0 ? -count : 0;
> 
> 	for(j = 0; j < image->rows; j++)
> 		for(i = 0; i < image->cols; i++)
> 			image->pixels[i][j] =
> 			  ((image->pixels[i][j] >> rshift) << lshift);
> 
> We are talking factors of two in execution time for these functions.
> What a pain !!

What is your solution?  Since most (I think all) hardware does not handle shift
count less then zero the compiler would have to generate the same code that it
generates for your example above.
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Alan Fargusson		Sun Microsystems
alanf@sun.com		..!sun!alanf