okay, let me try. On Sun, Jun 6, 2010 at 11:05 AM, Xiaohui Liu <[email protected]> wrote:
> Hi, > > Can I say event is at higher level while interrupt is at lower level? I > guess event handler may be sync if you look at Receive.receive() event. > An interrupt handler typically handles a h/w interrupt. In TinyOS you can find where we hook into the interrupt handlers by looking for TOSH_SIGNAL. In TinyOS, modules are interfaced using two mechanisms, commands for call in, and signals for call out. Signals are wired to event handlers. This is in the context of TinyOS. Other environments will vary. Commands and event handlers can be labelled as sync or async. Normally, one wants to keep everything sync. Life is simpler that way. TinyOS is about keeping things simple because less goes wrong that way. Its one of the reasons why static allocation is preferred over dynamic (ie. malloc). Wild pointers aren't much fun. However, one clearly needs to be able to signal asynchronous event too. Like how do we further connect to TinyOS modules from the interrupt handler? To denote that things can be happening in an asynchronous fashion, the keyword async word is used. The toolchain keeps track of the call chain and flags sync labelled routines that are callable from async routines because it violates the assumptions that make sync level stuff simple. Hopefully that adds some clarity. > Can you help me find an example of interrupt handler in TinyOS? Thank you. > Look for TOSH_SIGNAL. That is how code is hooked into the h/w interrupt handler. > > On Sat, Jun 5, 2010 at 3:28 PM, Ali Baharev <[email protected]> wrote: > >> Hi, >> >> "a callback subroutine in an operating system or device driver " >> http://en.wikipedia.org/wiki/Interrupt_handler >> >> When quoting, it helps to quote the whole thing... "An *interrupt handler*, also known as an *interrupt service routine* (*ISR*), is a callback <http://en.wikipedia.org/wiki/Callback_(computer_science)> subroutine in an operating system <http://en.wikipedia.org/wiki/Operating_system> or device driver <http://en.wikipedia.org/wiki/Device_driver> whose execution is triggered by the reception of an interrupt<http://en.wikipedia.org/wiki/Interrupt>. Interrupt handlers have a multitude of functions, which vary based on the reason the interrupt was generated and the speed at which the Interrupt Handler completes its task." The major difference between an event and an interrupt handler is how the event is generated. A h/w event is an interrupt and gets hooked in with TOSH_SIGNAL. An event handler is declared using "event void ..." and invoked using "signal ..." > --- >> >> "an event handler is an asynchronous callback subroutine that handles >> inputs received in a program" >> http://en.wikipedia.org/wiki/Event_handler >> >> Well that depends. On the context. There are places where that is true. However, we are talking about TinyOS. So the above confuses things. > Ali >> > > > > -- > -Xiaohui Liu > > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > -- Eric B. Decker Senior (over 50 :-) Researcher
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