R devel - Jul 2009 - how to change FPU control word?

Dear developers,

is there (already) a platform-independent way for (temporarily!) 
changing the fpu control word?
More precisely: I am looking for functions (accessible from C code in R 
packages) which read and write the fpu control word on x86 cpus (and 
cause no harm otherwise), because I need to (temporarily) turn off 
internal 80-bit precision for some algorithms relying on 64-bit IEEE 
arithmetics. Currently, I am using inline assembler (which works for x86 
cpus on Linux and Windows (MinGW)), but I am not sure what happens for 
other cpus/OSs (and I am not able to check this). I hope, there is 
already a better solution.
Any hints appreciated!

Thanks,
  Martin

-- 
Dr. Martin Becker
Statistics and Econometrics
Saarland University
Campus C3 1, Room 206
66123 Saarbruecken
Germany

On Mon, Jul 27, 2009 at 12:41:42PM +0200, Martin Becker wrote:
> is there (already) a platform-independent way for (temporarily!) 
> changing the fpu control word?
> Currently, I am using inline assembler (which works for x86 cpus on
> Linux and Windows (MinGW))
Platform-indepdendent?  I don't know about that.  But on Linux, mostly
x86-64, we use these from C:

  _FPU_GETCW()
  _FPU_SETCW()

-- 
Andrew Piskorski <atp at piskorski.com>
http://www.piskorski.com/