[avr-libc-dev] [bug #37104] ATtiny5/9/10/20/40 interrupt wrapper uses invalid register

[Jonathan Oakley]

URL:
  <http://savannah.nongnu.org/bugs/?37104>

                 Summary: ATtiny5/9/10/20/40 interrupt wrapper uses invalid
register
                 Project: AVR C Runtime Library
            Submitted by: jro_at_team
            Submitted on: Wed 15 Aug 2012 09:36:16 GMT
                Category: Library
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Unknown
                  Status: None
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 1.8.0
           Fixed Release: None

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Details:

I'm not sure if this is the fault of the library or GCC, but the
wrapper/prologue+epilogue generated for interrupt service routines by
ISR(vect) uses r0 and r1, which don't exist on the ATtiny5/9/10/20/40 family
(they only implement r16-r31). The result is six "register not supported"
errors when the intermediate assembler file is compiled.

The only workaround I can see is to use the ISR_NAKED attribute and generate
the correct wrapper yourself, which is obviously pretty tedious!




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