Date: Thu, 09 Nov 1995 09:28:58 +0100 From: Poul-Henning Kamp <phk@critter.tfs.com> To: koshy@blr.novell.com Cc: hasty@rah.star-gate.com (), freebsd-hackers@freebsd.org Subject: Re: Load/Store using FPU regs ... Message-ID: <6254.815905738@critter.tfs.com> In-Reply-To: Your message of "Thu, 09 Nov 1995 14:03:00 %2B0700." <30a1bccf0.4265@novidc.blr.novell.com>
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> >>>>> "Amancio" == "Amancio Hasty Jr " <hasty@rah.star-gate.com> writes: > > >>> L20: fldl (%ebx) fstpl (%ecx) ... > >>> > >>> The resulting program copies data at about 60 Megabytes per > >>> second. > > > Using the FPU registers for memmove/bitblt operations was a technique > I first saw on an i860. We used to do a series of reads into FPU regs > ... I think I saw something like that about 8 years back on an 20 year old system... > Now, I'm not sure if this approach can be used across all processors. > Some FPU's could raise exceptions if illegal bit-patterns are loaded > into its registers. The x86 FPU in particular has very few registers > and a LIFO access pattern for loads and stores so I don't know if the > same trick would work well for it. Not to mention that you might not have a FPU. I guess it would be interesting to try to do the zero of pages with it... -- Poul-Henning Kamp | phk@FreeBSD.ORG FreeBSD Core-team. http://www.freebsd.org/~phk | phk@login.dknet.dk Private mailbox. whois: [PHK] | phk@ref.tfs.com TRW Financial Systems, Inc. Future will arrive by its own means, progress not so.
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