Subject: Re: 64bit FP emulation
To: Toru Nishimura <locore32@gaea.ocn.ne.jp>
From: Simon Burge <simonb@wasabisystems.com>
List: port-mips
Date: 11/17/2002 15:20:14
On Sun, Nov 17, 2002 at 12:51:52PM +0900, Toru Nishimura wrote:
> We have to be serious about implementing 64bit FP insn emulation.
> It should be a full scale implementation even for cores equipped with
> no FP hardware. Note that no FP hardware is an extreme case of
> FP insn emulation and as long as emulation is smart enough
> there is no necessity to sprinkle SOFTFLOAT/NOFPU.
I keep meaning to try out the softfloat library (in libkern). 64-bit
FP will be easy with this, but I don't know the performance differences
between it and our current FP emulation for 32-bit math.
And yes, the SOFTFLOAT/NOFPU bit needs to be cleaned up at least. For
example, I'm not exactly sure how to build a kernel right now that
supports say both 5Kc (without FPU) and 20Kc (with FPU) such that the
FPU is used when it's available. Not that I've looked that closely.
> I once toyed an idea to approach Algorithmics but the company is...
Now that Algorithmics is part of MIPS I dunno if they'd be more or less
interested in releasing their FP emulation under a BSD-style licence...
Simon.
--
Simon Burge <simonb@wasabisystems.com>
NetBSD Development, Support and Service: http://www.wasabisystems.com/