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Subjectasm in C slightly OT
Can someone point be to some documentation on the asm capabilities in
gcc. In particular I find this in asm/hw_irq.h:

#define BUILD_COMMON_IRQ() \
asmlinkage void call_do_IRQ(void); \
__asm__( \
"\n" __ALIGN_STR"\n" \
"common_interrupt:\n\t" \
SAVE_ALL \
"pushl $ret_from_intr\n\t" \
SYMBOL_NAME_STR(call_do_IRQ)":\n\t" \
"jmp "SYMBOL_NAME_STR(do_IRQ));


The first line looks like a function proto type. It is unclear how it
is related to the rest of the macro. This macro generates a bit of code
that is not a function in any way. It has an entry label
"common_interrupt" and ends with a jmp. What I really want to know is
how to refer to a C variable inside of such a construct. The gcc
documentation talks about how to do it in more standard asm. I would
like, for example to add to the above macro, for example:

"incl foo.bar" where bar is a member of structure foo.

I know this could be done as: "incl foo+xxx" where xxx is the offset
of bar in foo, but I would like the compiler to figure this for me so as
to follow structure changes.

George

P.S. I know why this code is the way it is. What I am trying to
understand is how to add references to C data structures, not to
understand the what or why of this particular code fragment.

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