Experimental Physics and
Industrial Control System

Kay-Uwe Kasemir <[email protected]> · Thu, 10 Feb 2005 09:11:04 -0500

Hello:
Having learned the hard way,
I'm now quite aware of the VX_FP_TASK option
for vxWorks' taskCreate().
To be save inside ISR code, no matter how the compiler
optimizes your non-floating point code:
Are there vxWorks subroutines or asm(...)-type macros that allows
me to save/restore the FP registers?
If not, does anybody know the asm(..) lines that would work on
a PPC CPU?
Thanks,
-Kay
On Feb 9, 2005, at 13:02, J. Frederick Bartlett wrote:

Jeff,

...we did discover during the investigation that a FP register's
contents was being altered during the execution of the driver's
interrupt service routine (ISR) and that, even though no FP operations
were being performed in the ISR, the compiler optimization level that
we were using caused the FP registers to be used to store temporary
values.

...Jeff Hill wrote:

interrupt service routines as, on vxWorks, the FP
register contents are not saved / restored when
entering
/ exiting interrupt context. The driver must do this
manually if it finds a need to use FP in its ISR.

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System