From: nikki AT gameboutique DOT co (nikki)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: memcpy(); is there something faster?
Date: 25 Feb 1997 09:35:14 GMT
Organization: GameBoutique Ltd.
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

> Actually... The fpu memcpy and MMX memcpy which both copy 8 bytes at a time
> are basically the same. They're both using the same processor and fpu stack.
> 
> hmm.. gotta learn djgpp style asm so I can port it to djgpp..

if y'all want an fpu memcopy in inline asm for djgpp i wrote one here :)
sadly it's not as good as the old rep movsd though :( basically fpu memcopy
will outperform anything given that you can guarentee none of the 8bytes you
are moving will cause an fpu exception. if they do you have to do it the
'safe' way which gives you a transfer rate of 16bytes/16cycles and 1/2 as
many cache write misses. if it's 686 or higher you get 1/4 write cache misses.
sadly, if it's 686 or higher the rep movsd will go faster ;(
basically fpu memcopy is not all it's cracked up to be.

regards,
nik


-- 
Graham Tootell           
nikki AT gameboutique DOT com