Hi First of all, I'm also not an expert. :)
Similiarly, acoording to *TinyOS Programming Manual*, an async operation could preempt another async operation. So one interrupt handler could begin to execute before another interrupt handler finished. The next question is like this: does an aync operation could preempt an sync operation? Of course yes. You could found all of this knowledge in "TinyOS Programming Manual". Best Regards, Ruitao Xu 在 2011年4月14日 下午10:36，Sergio Valcarcel <[email protected]>写道： > Good point. > > Nevertheless, in my experience, I would say that when dealing with one > node receiving from many others, async command/function can happen > relatively easy, and some variables could be overwritten. So to > protect them could be worthy. > > I am not an expert, can the same event be called twice? Or rather, it > has to wait till the first call is finished? > > Another question: imagine that an event is executing and gets to call > a C like function. So immediately, the scheduler starts running the C > function. If the same event is called again before the C function has > finished, what could it happen? > I think that the event variables of the first call could be > overwritten with this second call. > Does it make sens? > > Cheers! > Sergio > > > On Thu, Apr 14, 2011 at 3:18 PM, 徐瑞涛 <[email protected]> wrote: > > Hi, > > > > Acoording to *TinyOS Programming Manual*, by default one function (it > could > > be event or command) is sync and it could only be preempted by an async > > function (for example: an interrupt handler). But, obviously, uartIn and > > uartQueue is private and can't be accessed in any async function. So, I > > think it's useless to put atomic here. > > > > Best Regards, > > Ruitao Xu > > > > > > 在 2011年4月14日 上午1:26，Sergio Valcarcel <[email protected]>写道： > >> > >> Hi, > >> > >> I imagine that either "uartQueue" or "uartIn" could be accessed from > >> another method. If it is not the case I do not see the usefulness > >> either. > >> > >> Have a great (perhaps sunny-spring) day!! > >> Sergio > >> > >> On Wed, Apr 13, 2011 at 9:55 AM, 徐瑞涛 <[email protected]> wrote: > >> > Hi, > >> > > >> > I'm also confused. Looking forward to detailed explanation. > >> > > >> > Best Regards, > >> > Ruitao Xu > >> > > >> > 在 2011年4月11日 上午10:07，许长亮 <[email protected]>写道： > >> >> > >> >> Hi: > >> >> > >> >> I am confued by the following keyword "atomic": > >> >> > >> >> > >> >> message_t* receive(message_t *msg, void *payload, uint8_t len) { > >> >> message_t *ret = msg; > >> >> > >> >> atomic { > >> >> if (!uartFull) > >> >> { > >> >> ret = uartQueue[uartIn]; > >> >> uartQueue[uartIn] = msg; > >> >> ... > >> >> } > >> >> ... > >> >> } > >> >> > >> >> I think the context of these codes excute is "task specific ", no > >> >> interrupt occurs. so there is no need to use the keyword "atomic". > any > >> >> on > >> >> give me a shorter explanation？ thanks! > >> >> > >> >> > >> >> Best regards! > >> >> > >> >> [email protected] > >> >> _______________________________________________ > >> >> Tinyos-help mailing list > >> >> [email protected] > >> >> > >> >> > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > >> > > >> > > >> > > >> > -- > >> > Be Your Personal Best! > >> > > >> > _______________________________________________ > >> > Tinyos-help mailing list > >> > [email protected] > >> > > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > >> > > > > > > > > > -- > > Be Your Personal Best! > > > -- Be Your Personal Best!
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