| From: | Rudi Chiarito |
| Date: | 10 Sep 2000 at 19:34:05 |
| Subject: | Re: AMIOPEN: C Inline VP |
On Sun, Sep 10, 2000 at 03:55:23AM -0700, artix wrote:
> I think this has been asked before but I don't remember the answer.
> Is there a way to include inline VP code in a C program? (like asm()
> under X86 gcc)
I knew somebody had to ask it, sooner or later! ;)
I did it this way (old, incomplete code):
void *pointer_to_gc_mark = &gc_mark;
__asm__ __volatile__
(
/*
WARNING: funky code ahead!
\t and \n are needed to make the final output easier to read
while debugging. Hopefully you'll never have to bother with all
of this.
*/
"\tsync\n" // spill all the registers
"\tsyncreg\n" // to the stack
"\tcpy.p %0,p1\n" // pointer to gc_mark
[...]
"\tret\n"
: // no output
: "a" (pointer_to_gc_mark)
: "p0", "p1", "p2", "i0"
);
In the example above, variable pointer_to_gc_mark is accessed as %0 in
the assembly source.
The help page file:/usr/doc/intent/lang/cc/doc/internal.html has a
section covering inline assembly code. I strongly suggest you also take a
look at gcc's documentation (the info manual, not the man pages, section
"C Extensions::Extended Asm") to learn more about helping the compiler
generate better code, with the use of constraints. Last but not least,
there's an excellent tutorial, which discusses x86 code, but is
nevertheless extremely helpful:
http://boudicca.tux.org/hypermail/linux-kernel/1998/1998week17/0377.html
(the name of the author, Colin Plumb, might be familiar to some, as he's
an ex Amiga programmer).