Subject:
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Re: bug in semaphore code (was Re: Announce: NQCIPC update
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 30 Oct 1999 00:17:42 GMT
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Viewed:
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928 times
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In lugnet.robotics, Robert Munafo writes:
> [...]
> Dave Baum and I and a few others talked about this issue 4 weeks ago in this
> thread:
>
> http://www.lugnet.com/robotics/rcx/nqc/?n=172
>
> The result was code that properly handles the lockstep starvation problem as
> well as making sure that only one task uses the semaphore at any given time.
> The solution requires the tasks to have task ID numbers.
>
> I will repeat the proper code here:
> [...]
Robert,
Cool stuff. I just added it here:
http://www.lugnet.com/robotics/rcx/nqc/?p=code
--Todd
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Message has 2 Replies:
Message is in Reply To:
 | | bug in semaphore code (was Re: Announce: NQCIPC update
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| Your semaphore acquire algorithm isn't too good. Here is your code: #define sem_acquire(s) until (s == 0); s = 1; If two tasks are waiting for the semaphore at the same time, it is quite likely that both will get it: // (s is currently nonzero) task (...) (25 years ago, 29-Oct-99, to lugnet.robotics)
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