From: David Fernandez <dfernandez@cct.co.uk>
To: "Ioannis E. Venetis" <venetis@capsl.udel.edu>
Cc: Ian Lance Taylor <iant@google.com>, gcc-help@gcc.gnu.org
Subject: Re: Address of label which is defined within an asm statement?
Date: Wed, 28 Jun 2006 16:00:00 -0000 [thread overview]
Message-ID: <1151510423.3070.13.camel@software.cct.co.uk> (raw)
In-Reply-To: <44A2960C.6040709@capsl.udel.edu>
On Wed, 2006-06-28 at 10:45 -0400, Ioannis E. Venetis wrote:
> Hello Ian,
>
> Thanks for answering this. I need to access the address of the label
> within the assembly code that I write. This means that I will have to
> check again the documentation of this architecture. I hope that I will
> find something.
>
> Best regards,
>
> Ioannis
>
> >
> > If you have a label in assembly code, and you want to use it in
> > assembly code, then you need to write whatever is appropriate for your
> > assembly language (e.g., "mov #MyLabel,r0"). That is not really a
> > compiler issue.
> >
> > If you have a label in assembly code, and you want to use it in C code
> > (e.g., by doing "goto MyLabel;"), then, sorry, you can't do that.
> >
> > Ian
To obtain the label address could be somthing like "mov #MyLabel, %<n>"
or "mov $MyLabel, %<n>" with <n> the output parameter number where you
get the result like : "=g" (MyLabelAddressVar).
To call a label from C code can be done using
goto *MyLabelAddressVar
I think that is a C Extension feature of gcc... You cold also pass the
value to another assembler block to do the trick, but that would be
architectural dependent some way...
"jmp *%0"
:
: "r" (MyLabelAddressVar)
David.
next prev parent reply other threads:[~2006-06-28 16:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-06-27 18:37 Ioannis E. Venetis
2006-06-28 6:08 ` Ian Lance Taylor
2006-06-28 14:41 ` Ioannis E. Venetis
2006-06-28 16:00 ` David Fernandez [this message]
2006-06-28 22:28 ` Ioannis E. Venetis
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