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Article #407Re: fast memcpy
From: oleg kibirev
Date: Tue, 21 Jul 1992 16:26
Date: Tue, 21 Jul 1992 16:26
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In article <1992Jul19.234636.25680@ccu1.aukuni.ac.nz> stuartw@ccu1.aukuni.ac.nz (Stuart Woolford) writes: > >in microsoft ( 5.0 and 6.0, atleast... ) a memcpy is done with an inline >string move instruction, ie:no call overhead, short of using DMA, there >is no way of going faster ( I think it uses word move, but could be wrong.. ) > So, each time you use memcpy, optimization is turned off for the entire module? Or it's only Borland's reacrion to ASM? I think there is a way to do it faster (sometimes): checking if the start of both source and dest are misaligned and fixing it with single movsb before doing word move. DMA won't be faster on anything better than 4.77MHz PC: it operates at 4MHz on all later machines. Oleg Kibirev
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Newsgroups: comp.os.msdos.programmer Path: arc1-ca.pugleaf.net!sparky!uunet!caen!sol.ctr.columbia.edu!csa!kibirev From: kibirev@csa.bu.edu (oleg kibirev) Subject: Re: fast memcpy Organization: Computer Science Department, Boston University, Boston, MA, USA References: <2a66baaf@ralf> <1992Jul19.234636.25680@ccu1.aukuni.ac.nz> Message-ID: <1992Jul21.162618.25425@ctr.columbia.edu> Sender: news@ctr.columbia.edu (The Daily Lose) Date: Tue, 21 Jul 1992 16:26:18 GMT X-Posted-From: csa.bu.edu X-Posted-Through: sol.ctr.columbia.edu Lines: 17