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Lou Sortman wrote:
> > ID TO FROM LENGTH ..... CHECKSUM(16 or 8 bit? probably 16)
>
> What is the ID? Is it for framing? Is it a byte that is not currently
> taken up by a Lego bytecode? Do we even care about colliding with Lego's
> communication protocol?
Yes, it's a start byte. Jacob suggested using 0xFn to identify protocol
versions, 0xFF being the LEGO standard.
> > Tasks could register to receive messages from certain ports. But can
> > that replace suspend/resume? I think not.
>
> Suspend/resume is a different subject, isn't it? It has been suggested to
> me that tasks could be suspended simply by changing their state to something
> like "P_SUSPEND" (and changing the scheduler to deal with it). That is much
> simpler than the way that I had been thinking of implementing it (with a
> separate queue for suspended processes in each priority level). That's the
> easy part, though. First, we would need signals.
Actually, you wouldn't have to change much, just treat P_SUSPENDED tasks
like they're P_WAITING and the condition failed. suspend(pid) and
resume(pid) wouldn't really need signals that way, as the pid equals the
address of the
process data block - we could manipulate it directly.
> I'd expect to wait for a datagram by doing the wait_event() thing. Either
> explicitly or wrapped in a function which also grabs the datagram from my
> task's point of view.
Uh, what about datagrams arriving faster than the task can handle,
because it is low priority? We need buffers somewhere.
--
Markus L. Noga noga@inrialpes.fr
Check out legOS! http://www.multimania.com/legos/
"Quand on n'a pas de caractere, il faut bien se donner une methode."
-Camus on Software Engineering
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Message has 1 Reply:
 | | Re: Idle process
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| (...) That is true. (...) Yes, we do, but is that something the tasks need to worry about? If the kernel has buffered 3 datagrams since the last timeslice, the next 3 waits would return immediately, since their criterion (datagram ready for reading) (...) (28 years ago, 20-Mar-99, to lugnet.robotics.rcx.legos)
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Message is in Reply To:
| | Re: Idle process
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| (...) Cool! (...) I had been thinking along the same lines. (...) What is the ID? Is it for framing? Is it a byte that is not currently taken up by a Lego bytecode? Do we even care about colliding with Lego's communication protocol? (...) (...) (28 years ago, 19-Mar-99, to lugnet.robotics.rcx.legos)
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