[avr-gcc-list] On getting an ISR leaner with GCC

[dlc]

The subject says it all.  I've an ISR that is using too many cycles for 
something that kicks every 10us.  I'm very experienced with the PIC and 
know how to specify registers that are not touched outside of the ISR to 
avoid lots of "push-n-pop" actions.  Is there something like that in the 
AVR toolchain or am I going to have to resort to assembly to get this 
thing leaned down?  I'd like to create some memory that is dedicated to 
the ISR such that the compiler knows that it doesn't need to be saved. 
Also a way to get scratchpad memory assigned to it for some basic math 
that I don't want to have to use the overhead of push/pop.  Can anyone 
offer insight into how I can lean an ISR down or what sorts of 
operations or memory types to avoid there with avr-gcc?

many thanks,
DLC
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Dennis Clark          TTT Enterprises
www.techtoystoday.com
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