[avr-gcc-list] Use of variables and programming in avr-gcc

[Robert Rozman]

Hello,

I'm relatively newbie to avr-gcc. I've not found any reference/advice on
how to declare variables and how to use them in avr-gcc. Ther is only
one Application note on atmel site about efficient programming in C, but
it is for one of commercial compilers.

I've several question and I'd kindly ask if someone from more
experienced guys is willing to organize his experience in few sentences
of advice to novice users. Among other I have few specific questions:
- do recomendations from mentioned application note apply also for
avr-gcc ? if not, what should be done differently ?
- what declaration keywords are really implemented and what is their
effect (const, register, volatile, ...) and how exactly to use them ?
- is it better to keep SRAM variables in structures - as APP note
recomends) or not ?

I'd kindly ask for answers in code space and also from speed point of
view.

Thanks in advance and special thanks to all guys working on avr-gcc,

Robert Rozman