> Undefined means that this situation is not specified by the standard.
> The compiler is free to assume that this points to a valid instance and to
> do what it wants with it. So if you ever switch to another compiler or
the > gcc folks decide for whatever reason to do something fancy in methods,
you > are lost. This is not very likely, but nevertheless an avoidable risk.
For > principle reasons such risks should be avoided.
Except that this is only required if the method needs to implicitly access
either the class's data or other class methods - not the case with the
interrupt handlers being discussed here. But I concede that whether a this
is provided by the compiler when the "signal" attribute is used is compiler
specific, sometimes even context specific. As we agree - use "static".
> > Yes, this is almost working. In the avr-gcc case, a plethora of
> > processors
> > have much the same peripherals and the compiler managers have rightly
> > standardized on common names for common peripherals, with the
> > translation to
> > the correct vector done via processor specific macros. My last
> > problem looks
> > like it should be easy but I have run out of ideas. It is in the
> > method
> > declaration. For example:
> >
> > static void MyOverflowInterrupt(void) asm(TIMER0_OVF_vect)
> > __attribute__ ((signal, __INTR_ATTRS));
> >
> > Somewhere in the device header for a particular processor is the
> line:
> >
> > #define TIMER0_OVF_vect _VECTOR(16)
> >
> > And elsewhere is defined:
> >
> > #define _VECTOR(N) __vector_ ## N
> >
> > So the definition becomes the almost correct:
> >
> > static void MyOverflowInterrupt(void) asm(__vector_16)
> > __attribute__ ((signal, __INTR_ATTRS));
> >
> > How do I get it to be:
> >
> > static void MyOverflowInterrupt(void) asm("__vector_16")
> > __attribute__ ((signal, __INTR_ATTRS));
>
> Oh, this one is actually easy :-)
>
> You just need another macro-indirection that uses the "stringify"
> operator (#) of the pre-processor:
>
> >>>>
> lohmann@mocca:~/tmp$ cat test.cpp
> #define TIMER0_OVF_vect _VECTOR(16)
> #define _VECTOR(N) __vector_ ## N
>
> #define IRQ_VECTOR(vec) asm(#vec) __attribute__ ((signal,
> __INTR_ATTRS))
>
> class Timer0 {
> static void MyOverflowInterrupt(void) IRQ_VECTOR(TIMER0_OVF_vect);
> };
> <<<<
>
> After pre-processing this becomes:
>
> >>>>
> lohmann@mocca:~/tmp$ g++ -E test.cpp
>
> class Timer0 {
> static void MyOverflowInterrupt(void) asm("TIMER0_OVF_vect")
> __attribute__ ((signal, __INTR_ATTRS));
> };
> <<<<
>
> Daniel
>
> P.S. Answers to to the list, please. Other readers might be
> interested and contribute as well.
Sorry, I was not too clear here. The user does not really know the vector
number, only the "TIMER_OVF_vect" name. So the user definition:
static void MyOverflowInterrupt(void) asm(TIMER0_OVF_vect)
__attribute__ ((signal, __INTR_ATTRS));
must end up after macro substitution being presented to the compiler like:
static void MyOverflowInterrupt(void) asm("__vector_16")
__attribute__ ((signal, __INTR_ATTRS));
Perhaps not quite so easy :-(
Ron
E-mail message checked by Spyware Doctor (5.5.0.178)
Database version: 5.09090
http://www.pctools.com/spyware-doctor/
