On Mon, 2001-09-17 at 12:32, Dan Sugalski wrote:
> At 12:20 PM 9/17/2001 -0400, Gregor N. Purdy wrote:
> >Brian --
> > > > It would also be helpful to have jump_ic and absjump_ic, rather than
> > > > having to load these things into registers.
> > >
> > > You can use branch_ic for this. absjump is probably a bad idea since it
> > > appears the return value of the opcode function is really a memory
> > > address of the host machine. If an absolute value (relative to the
> > > beginning of the opcode stream) was used, then it would have to be
> > > relocated at load-time and wouldn't be able to remain read-only.
>
> This isn't actually a problem, as there are times we will want to return
> absolute addresses. Granted they'll be fetched from some place and not
> generated at compile time, but useful nonetheless. (For things like sub
> entry points and such, where we're potentially jumping into other code
> regions)
Jako likes absolute (chunk-relative) addresses a lot for simple
example and test programs.
> >My mental model for this thing is "Parrot is a CPU architecture" and
> >a lot of what I'm trying to make it do is behave as much as possible
> >in that way. So, if we are talking about a CPU architecture (ISA),
> >lacking the full complement of relative and absolute jumps, register
> >and constant comparisons, etc. is a bummer.
>
> Give me a bit. I'm ignoring e-mail (mostly) and getting a bunch of work
> done. I'm getting the generic stack and jsr/ret stuff done in the
> interstices between work. :)
I appreciate your work and responsiveness so far. I'm actually having
fun trying to work around the missing bits to get just enough working
stuff that Jako becomes interesting to folks other than me.
For instance, I'd like to see tests and examples in t/ get generated
from jako source (at least some of them).
I'd also like to get enough features into the language that folks
go: "Hey! Jako would be a great language for implementing other parts
of Perl6 (things that should run on the virtual CPU rather than on
the host CPU). This may be a bit much to shoot for, but that's what
would make it the most fun.
> > > Overall, I think you're barking up the wrong tree. jsr/ret are for
> > > subroutines.
>
> I should point out that these are assembly level subroutines, not Perl
> level subroutines. There'll be a separate HLL sub call op/return pair.
I wonder... What could I add to Jako so that it could be used to
implement a simple PMC type? How much more architecture work needs to
be done before we could start having simple examples that use PMC
registers?
> >Of course, this doesn't allow us to do recursion, wastes registers,
> >etc. But, it would allow me to play with the syntax of the language
> >with a simple implementation until cooler ops are available.
>
> You can recurse if you clone the register file at 'subroutine' entry.
I haven't played with this yet. Although if I do that, how do I return
a value to my caller?
Regards,
-- Gregor
_____________________________________________________________________
/ perl -e 'srand(-2091643526); print chr rand 90 for (0..4)' \
Gregor N. Purdy [EMAIL PROTECTED]
Focus Research, Inc. http://www.focusresearch.com/
8080 Beckett Center Drive #203 513-860-3570 vox
West Chester, OH 45069 513-860-3579 fax
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