Preston Wilson wrote: > "Stu Bell" wrote: > > > Hi all, > > > > I'm chasing down a problem with WinAVR 20080430 and my ATmega2560 code. > > In generated code comparisons of an ISR between 20071221 and 20080430, > > I noticed that r30 and r31 are not saved on the stack. Normally, this > > wouldn't be a problem as the ISR itself does not use r30/r31. > > > > However, this ISR calls a function that does use r30/r31. Again, it > > *should* be no problem, since the function has the responsibility to
> > store r30/r31 if it uses it. > > It is the callers responsibility to save r30 and r31 registers if they > are needed across a function call. At least that is my reading of the > following FAQ. > > http://www.nongnu.org/avr-libc/user-manual/FAQ.html#faq_reg_usage > > I admit I do not know what is supposed to happen if an ISR is using a > call-used register. > > -Preston Up until WinAVR 2008*, the ISR took the monkey to save those registers. This appears to be a breakdown of the ISR prologue, although I have not confirmed that yet with a test case. Best regards, Stu Bell DataPlay (DPHI, Inc.) _______________________________________________ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
