[Icc-mot] uexec and XGATE chip

[Peter Lissenburg]

Hi Edward,
	with
ldaa	#0
psha
in those places you pointed out and all works fine.
Now to keep my eyes open for other differences.

Thanks for your help.
Peter L.



Peter Lissenburg wrote:
> Hi Edward,
>     thanks for that, important point I had missed, although I should 
> have questioned the extra stuff NoIce was showing me.
> Before the
> CLR 1,-SP
> should I not make another entry to modify? by
> psha
> ?
> 
> I'll have a go and learn more....
> Thanks.
> Peter L.
> 
> 
> 
> Edward Karpicz wrote:
>> Peter Lissenburg wrote:
>>
>>> Hi Richard and all,
>>> I'm starting to use the uexec code on an xgate chip. Finding a 
>>> problem(s),
>>> that I have not tracked down yet, so I thought I'd ask if anyone has 
>>> done
>>> this and solved this (unknown as yet!) problem.
>>> Thanks for any insights.
>>> Peter L.
>>>
>>>
>>
>> Hi Peter,
>>
>> S12X CCR is 16bits wide, while S12 CCR is 8bits wide. As a result 
>> interrupt stack frames do differ. This doesn't hurt anybody except 
>> when code has to manipulate interrupt stack frame. I found two 
>> "suspect places" in hc12.s file from examples12\uexec_dp256.zip, 
>> please search for "create an interrupt stack frame":
>>
>> ...
>> _UEXC_SavregsAndResched::
>> ; first create an interrupt stack frame
>> pshy
>> pshx
>> pshd  ; what a concept, not A:B
>> tpa
>> anda #0xEF ; re-enable interrupt when it "returns" since
>> psha  ; Defer() disables interrupt
>> ...
>>
>> In bottom three lines 8bit CCR is pushed to the stack. CCRh should be 
>> pushed next. CCRh holds interrupt priority level and it should be zero 
>> for foreground tasks. So add CLR 1,-SP after psha and it should get 
>> ported, I think.
>>
>> ...
>> _UEXC_SavregsAndResched::
>> ; first create an interrupt stack frame
>> pshy
>> pshx
>> pshd  ; what a concept, not A:B
>> tpa
>> anda #0xEF ; re-enable interrupt when it "returns" since
>> psha  ; Defer() disables interrupt
>>   CLR   1,-SP
>> ...
>>
>> ...
>> _UEXC_StartNewTask::
>> lds _uexc_current_sp
>> ; make KillSelf as the "return pc" of a new task, so if it
>> ; ever returns, it will reclaim the storage
>> ldd #_UEXC_KillSelf
>> pshb
>> psha
>> ldd _uexc_current_func
>> pshb
>> psha
>> ; create an interrupt stack frame
>> pshy
>> pshx
>> pshd
>> tpa
>> anda #0xEF ; re-enable interrupt
>> psha  ;
>>   CLR   1,-SP
>> ...
>>
>>
>> Regards
>> Edward
>>
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>>
>>
> 
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