Hmmm. It seems to me that you can check the STCBBFP flag both at save
time and at restore time:
* If off at save time, then don't save them, but remember that it was off.
* At restore time, if STCBBFP had been off at save time, but now
is on, then you know that the signal handler did, indeed, use the AFP
regs, in which case, you can "restore" them simply by zeroing them.
Wouldn't that work?
Dave Cole
At 9/27/2017 01:25 PM, Thomas David Rivers wrote:
The problem is that a BPX SIR needs to save/restore the floating-pt
registers before invoking the signal handler.
Checking the CVT bits is all well-and-good, but then unconditionally
saving all 16 registers then will cause MVS to set the bit in CR0.
If the program has no need to save/restore all of the FP registers (because
it's not using them) it would be nice if the BPX signal handler
didn't accidently
kick the AFP bit of CR0 "on" by using the AFP registers.
That is - I'm in this state of "If the AFP regs haven't been used, I don't
want to be the one to use them, but if they have I need to
save/restore them."
But - on reflection - perhaps that is incorrect thinking... the
invoked signal
handler may use the AFP registers. In fact, it might be the first such use
in the execution of the program. In that case, the SIR should have
saved/restored
all the AFP registers, even though CR0's AFP bit might have been
"off" at the start
of the SIR. Since the SIR can't know what the handler is going to do;
I guess it's stuck at always saving/restoring the AFP regs if the
CVTBFPH flag
is on...
- Thanks everyone! -
- Dave Rivers -
--
[email protected] Work: (919) 676-0847
Get your mainframe programming tools at http://www.dignus.com
----------------------------------------------------------------------
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO IBM-MAIN
Dave Cole
ColeSoft Marketing
414 Third Street, NE
Charlottesville, VA 22902
EADDRESS: <mailto:[email protected]>[email protected]
Home page: www.colesoft.com
LinkedIn: www.xdc.com
Facebook: www.facebook.com/colesoftware
YouTube: www.youtube.com/user/colesoftware
----------------------------------------------------------------------
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO IBM-MAIN
