Subject:
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Re: signals / legOS internals
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Sat, 26 Jun 1999 06:54:16 GMT
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Viewed:
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1264 times
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Lou Sortman <theball@bigfoot.com> wrote:
> So, should I abandon my implementation? If something every bit as good
> is already there, it may be silly for me to continue. I haven't looked
> at Librcx yet, so I don't completely understand how it works.
No, you should not abandon your implementation - not if you want to use
LegOS. I was only explaining how I implemented similar functionality, for
the sake of comparison.
Regarding Librcx, I might release another version at some point, to add
more-generalized non-ROM support for all types of i/o, but who knows when
that will happen. I have been playing around with other things lately, and
have not been spending too much time with my RCX.
> I think one of the original reasons for implementing signals may have
> been to suspend and resume tasks.
That is a reasonable, per-thread thing that I had not thought of using
signals for and that my signal-like implementation does not handle.
But why do you need signals to do that? If you are a thread, and you have
a reference to another thread (pid, pointer to thread data structure,
whatever), then there should be functions for you to manipulate the thread
you have a pointer to, including suspending and resuming that thread.
Or maybe signals are a nicer way of doing this in some cases I haven't
thought of?
> > Actually, I bet this is slightly different from the signal mechanism being
> > discussed, which probably has one vector per thread/process. Librcx only
> > has a single, global set of vectors.
>
> Ok, I know I'm being dense, but what are the implications of this?
If there is only one vector that gets called when a specific event occurs
(say, a button is pressed), then only one thread can hook into that vector.
Therefore, you might way that the vectors are not very thread-friendly.
But they are not supposed to be. The vectors are meant to be very
low-level hooks, internal to the library but there if you want to modify
them. The default thing hooked into a vector (if anything is hooked into
the vector) is supposed to be some other part of the library, something
that provides higher level event notification to any number of threads.
-Kekoa
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Message has 1 Reply:
 | | Re: signals / legOS internals
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| (...) Cool. I will proceed. (...) Yup. I was out of the loop for awhile, and am once again whompin' on this project. (...) That is true. Signals would give the task the opportunity to stop/start tasks under its control, though, without the task that (...) (25 years ago, 26-Jun-99, to lugnet.robotics.rcx.legos)
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Message is in Reply To:
| | Re: signals / legOS internals
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| (...) So, should I abandon my implementation? If something every bit as good is already there, it may be silly for me to continue. I haven't looked at Librcx yet, so I don't completely understand how it works. I think one of the original reasons for (...) (25 years ago, 26-Jun-99, to lugnet.robotics.rcx.legos)
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