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Mail Archives: djgpp/1997/04/15/02:46:20

From: Tom Burgess <Tom_Burgess AT bc DOT sympatico DOT ca>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: What is faster STOSD or MOVSD
Date: Mon, 14 Apr 1997 21:51:32 -0700
Organization: BCTEL Advanced Communications
Lines: 14
Message-ID: <33530954.4366@bc.sympatico.ca>
References: <5iu501$rqj AT nr1 DOT toronto DOT istar DOT net>
NNTP-Posting-Host: pntn02m01-21.bctel.ca
Mime-Version: 1.0
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Jeff Weeks wrote:
> 
> Which is faster?
> 
> rep stosd or
> rep movsd
>               486 cycles    Pentium
rep movs:     11+(3.3)n     13+(1.1)n
rep stos:     8+(4.1)n      5+(4.5)n

rep movs wins (for aligned transfers within primary cache). Recommended
book for good info on optimization issues: "Inner Loops" by Rick Booth.

	regards, tom

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