m68040 FPSP question

Eric Norum norume at aps.anl.gov
Wed Feb 25 15:59:28 UTC 2004

Chris Johns wrote:
> Is the FPSP the software emulation of the instructions missing from the 
> 68020 ?

The 68040 Floating Point Support Package provides support for the floating 
point instructions missing on the 68040 (and, using a different package, the 

> If so then I suggest you consider using a -m68040 for newlib (which 
> should already be done) and RTEMS. This removes the need for any 
> emulation software.
> IMO this library is only needed if you have a binary which needs to be 
> moved from the 68020 to the 68040.

The FPSP also provides emulation for additional rounding modes and exception 
masking (i.e. to support silent truncation to 0) so it really is necessary.

> I use a multilib RTEMS for the 68EC060 without any emulation and it 
> works fine (the EC does not have a FP unit so also have -msoft-float).
>  > Are there any user-entry points to FPSP at all
>  > (apart from the installation routine, of course)?
As far as I can recall there are no user entry points to the FPSP.  It's 
intended to be placed in the kernel and to hide the CPU differences from the user.

Eric Norum                                 norume at aps.anl.gov
Advanced Photon Source                     Phone: (630) 252-4793
Argonne National Laboratory

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