Re: [avr-gcc-list] Save RAMPZ register in interrupt handler routines

[Anatoly Sokolov]

Hi.

From: "David Brown" <address@hidden>
Sent: Sunday, January 27, 2008 10:57 PM

> I'd imagine that the use of pgm_read_*_far macros
> within interrupt functions is pretty rare - perhaps the best idea is to
> use the patch, but make "-mno-save-rampz" the default?

Rare for 128K devices, but are more required for 256K devices. Also, as the 
Dmitry wrote, some instructions ('LD R,Z+') can change the RAMPZ register. I 
consider that by default saving of the RAMPZ register in interrupt handler 
routines should be enabled.

> Or is there some
> practical way to let the interrupt function save rampz if and only if it
> is used (or if a function is called), just like the volatile registers?
>

With this patch avr-gcc should save the RAMPZ register, only if the Z 
register (r30:31) is used in interrupt handler routine.

Anatoly. 


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