Re: A float point arithmetic in kernel extension
Re: A float point arithmetic in kernel extension
- Subject: Re: A float point arithmetic in kernel extension
- From: Quinn <email@hidden>
- Date: Tue, 7 Mar 2006 10:30:20 +0000
At 21:56 -0800 6/3/06, Mike Smith wrote:
Floating point math is not generally supported in the kernel; you'll
need to find another way of doing what you need to do.
Just to clarify this, we /do/ support the use of floating point (and
vector) instructions in kernel code. For example, the Mac OS X audio
sub-system makes extensive use of floating point in the kernel.
However, there are caveats. This topic is covered pretty well in the
documentation.
<http://developer.apple.com/documentation/Darwin/Conceptual/KernelProgramming/style/chapter_5_section_5.html>
The problem you're seeing is not related to floating point
instructions, per se, but to floating point libraries. The
availability, in kernel, of commonly used library functions is also
covered in the documentation.
<http://developer.apple.com/documentation/Darwin/Conceptual/KernelProgramming/style/chapter_5_section_4.html>
Unfortunately, standard floating point library functions, like pow
and acos, are not present in the kernel. In this respect, the
difference between Xcode 1.5 and Xcode 2.2 is an improvement; there's
no point allowing you to include <math.h> if the functions aren't
available anyway.
You will have to eliminate your dependency on these functions. I'm
not a Maths Geek (tm), but there's got to be a way...
S+E
--
Quinn "The Eskimo!" <http://www.apple.com/developer/>
Apple Developer Technical Support * Networking, Communications, Hardware
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