From owner-freebsd-hackers Thu Nov 9 01:50:11 1995 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.6.12/8.6.6) id BAA01407 for hackers-outgoing; Thu, 9 Nov 1995 01:50:11 -0800 Received: from tfs.com (tfs.com [140.145.250.1]) by freefall.freebsd.org (8.6.12/8.6.6) with SMTP id BAA01390 for ; Thu, 9 Nov 1995 01:50:03 -0800 Received: from critter.tfs.com by tfs.com (smail3.1.28.1) with SMTP id m0tDTad-0003wZC; Thu, 9 Nov 95 01:48 PST Received: from localhost (localhost [127.0.0.1]) by critter.tfs.com (8.6.11/8.6.9) with SMTP id JAA06256; Thu, 9 Nov 1995 09:28:59 +0100 X-Authentication-Warning: critter.tfs.com: Host localhost didn't use HELO protocol To: koshy@blr.novell.com cc: hasty@rah.star-gate.com (), freebsd-hackers@freebsd.org Subject: Re: Load/Store using FPU regs ... In-reply-to: Your message of "Thu, 09 Nov 1995 14:03:00 +0700." <30a1bccf0.4265@novidc.blr.novell.com> Date: Thu, 09 Nov 1995 09:28:58 +0100 Message-ID: <6254.815905738@critter.tfs.com> From: Poul-Henning Kamp Sender: owner-hackers@freebsd.org Precedence: bulk > >>>>> "Amancio" == "Amancio Hasty Jr " 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.