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SubjectRe: asm in C slightly OT
"H. Peter Anvin" wrote:
>
> Followup to: <39795FCE.65EE2768@pioneer.net>
> By author: George Anzinger <george@pioneer.net>
> In newsgroup: linux.dev.kernel
> >
> > 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.
> >
>
> RTFM(info gcc)
>
> asm("incl (%0)" :: "i" (&foo.bar));

I wish it was that easy. As it turns out the asm statement is not
inside a function. This seems to turn off the ability to use the ":"
construct. Why? Wish I knew. At this point I think I must use hand
computed offsets for members of structures refered to from asm code that
is not in a function.


George

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