Subject:
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Re: Why java is (not) bad for Mindstorms
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 24 Jan 2006 13:21:52 GMT
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Viewed:
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1527 times
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In lugnet.robotics, "Laurent Desnogues" <Laurent.Desnogues@arm.com> wrote:
>
> In lugnet.robotics, pisymbol Clague wrote:
> >
> > I mean the NXT
> > could already have a JIT type execution environment already
> > whereby the
> > graphical IDE generates pseudo-code ("bytecode") and the
> > firmware on the NXT
> > does the dynamic translation on the fly. I don't know, but
> > the above *seems*
> > reasonable to me. Moreover, future versions of the NXT
> > compiler within the
> > graphical IDE would be compatible with any platform changes
> > (new JIT firmware).
> >
> > Right?
>
> Wrong :) For two reasons:
>
> - a JIT is quite complex if you want to really gain
> something and requires too much memory (remember
> the NXT only has 64 KB of RAM);
I believe there are JIT for J2ME environments which can be as low as 128KB of
RAM. I'm not disagreeing with you, I'm just stating that the JIT technology is
applicable to embedded systems and the argument of "its too complex" doesn't
always apply (probably does in this case).
> - JIT and real-time are not good friends...
Sure, sure...
> Of course, there are two assumptions here: that the
> bytecode is low level and that the interpreter is fine
> tuned for speed. But if the bytecode is not low level then
> it means that each operation does complex tasks and so
> compiling would not bring much anyway. This leaves us with
> the potential problem of a too slow interpreter and to what
> Steve Hassenplug talked about: a faster firmware.
Yeah, I believe my understanding of JIT technology is that the intermediate
bytecode has to be somewhat low-level to make runtime compilation easy (and
already half optimized). If the bytecode is high-level as you put it, then
yeah, it would seem to me that JIT would get you nothing if not slow you down.
-aps
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Message is in Reply To:
 | | RE: Why java is (not) bad for Mindstorms
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| (...) Wrong :) For two reasons: - a JIT is quite complex if you want to really gain something and requires too much memory (remember the NXT only has 64 KB of RAM); - JIT and real-time are not good friends... On top of that, a carefully implemented (...) (18 years ago, 24-Jan-06, to lugnet.robotics)
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