Re: Internal handling of interrupt vectors and jump table
Am 08/11/2015 um 12:04 PM schrieb Klaus Rudolph:
> can someone explain how interrupt vectors are handled in gcc internally?
ISR functions are implemented as function attributes, i.e. there are
avr-specific function attribute (__interrupt__, __signal__) which turn an
ordinary function into an ISR. Main outcome of these attributes is that
./gcc/config/avr/avr.c::avr_expand_prologue() emits a different prologue for
ISRs. Similar for avr_expand_epilogue().
Attribute handling like special diagnostics for ISRs is performed by
> OK, I saw that in /opt/avr_5.2.0/lib/gcc/avr/5.2.0/../../../../avr/lib/avr5/crtatmega32.o
> the empty vector table is included, like:
> Disassembly of section .vectors:
> 00000000 <__vectors>:
> 0: 0c 94 00 00 jmp 0 ; 0x0 <__vectors>
> 4: 0c 94 00 00 jmp 0 ; 0x0 <__vectors>
> 8: 0c 94 00 00 jmp 0 ; 0x0 <__vectors>
> And I also can see, that my code results in:
> Disassembly of section .text:
> 00000000 <__vector_7>:
The .vectors section is implemented in AVR-LibC's gcrt1.S.
ISR and similar macros are provided by interrupt.h.
> but where can I see that __vector_7 goes to the correct place in the table?
To see the macros after expansion compile with -save-temps and read the
respective .i file (C) or .ii file (C++).