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Re: [avr-libc-dev] volatile in pgmspace.h ?


From: E. Weddington
Subject: Re: [avr-libc-dev] volatile in pgmspace.h ?
Date: Mon, 16 Jun 2003 15:44:35 GMT

> Good day!
> 
> I have subscribed on "avr-libc-dev" only a few days back 
and,
> probably, not I know all circumstances of this decision.
> 
> In my opinion, there is no necessity to 
include "volatile" in
ÍÁËÒ> Ï "__LPM" 
> and other. The result of reading (the second argument 
asm), instead of
the>  
> fact of presence of a code "lpm" in the given place is 
important only.
> 
> Presence "volatile" does not enable to lead quite 
justified optimization.

Originally, the inline assembly had not been marked 
volatile. However, I had gotten a bug report stating that 
the GCC optimizer had rearranged the inline assembly to the 
point where it wasn't working as defined. The fix was to 
mark all the inline assembly macros as volatile so the 
optimizer will leave them alone and have them work as 
defined. It would be great if you have a better solution 
that would work under all levels of optimization.

Eric
Weddington






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