The compiler only save registers which are needed by the isr. Why you
should do this by your own?
Hi all,
I'm working on a hard realtime application where I need to keep the time
where interrupts are disabled as small as possible. I've noticed that a
typical ISR can take 40+ cycles to push registers onto the stack before
executing any user ISR code. I'd like for interrupts to be re-enabled
immediately upon entering the ISR (before the context save).
The only way that I can think of to do this is to add the naked attribute
to my ISRs. Unfortunately, this is very unattractive because then I have
to do all context save operations manually. My ISRs are written in C and
therefore I wouldn't know which registers would need to be saved and would
be forced to save all of them --- an expensive proposition.
Is there a way to inject a simple sei() into the start of an ISR before
the automatic context save?
Thanks,
David Carr
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