From owner-freebsd-current Wed Jun 10 23:19:51 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id XAA01567 for freebsd-current-outgoing; Wed, 10 Jun 1998 23:19:51 -0700 (PDT) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from labinfo.iet.unipi.it (labinfo.iet.unipi.it [131.114.9.5]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id XAA01542 for ; Wed, 10 Jun 1998 23:19:46 -0700 (PDT) (envelope-from luigi@labinfo.iet.unipi.it) Received: from localhost (luigi@localhost) by labinfo.iet.unipi.it (8.6.5/8.6.5) id GAA21849; Thu, 11 Jun 1998 06:43:09 +0200 From: Luigi Rizzo Message-Id: <199806110443.GAA21849@labinfo.iet.unipi.it> Subject: Re: floating point usage within the kernel - howto ? To: mike@smith.net.au (Mike Smith) Date: Thu, 11 Jun 1998 06:43:08 +0200 (MET DST) Cc: current@FreeBSD.ORG In-Reply-To: <199806110503.WAA00904@antipodes.cdrom.com> from "Mike Smith" at Jun 10, 98 10:03:30 pm X-Mailer: ELM [version 2.4 PL23] Content-Type: text Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > > a local user has a need to do some Floating Point computations within > > the kernel. I think this is not possible without explicitly ... > The simple answer is "don't do it". You might try '-msoft-float' as a > compiler option, but it'd be better just to come up with a fixed-point > or manually-coded floating point implementation. > > What do they want to do FP in the kernel for anyway? they want to run a P-I-D controller (and more generic controllers if this goes well) to control a few motors, for didactical purposes. The used to do the same thing under DOS, by hooking this 'real-time' task to the timer interrupt. I am trying to push them to use FreeBSD (and an LKM for this module) so that they can easily access the controller across the network or via the web, use high level stuff for visualization, etc. For sure they can do fixed point, but if i can find a solution for 'save_fp_regs()/restore_fp_regs()' this might have other uses as well. cheers luigi -----------------------------+-------------------------------------- Luigi Rizzo | Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it | Universita' di Pisa tel: +39-50-568533 | via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 | http://www.iet.unipi.it/~luigi/ _____________________________|______________________________________ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message