Mido, In general, there is no preemption of any kind in vanilla tinyos. There are interrupts which can disrupt the normal execution of a program, these are usually denoted by the "async" keyword. There is only a single thread of execution so if one event or task takes a very long time, it will delay other tasks.
If you want to execute a very long computation (without backlogging events) it would be best to split it up into many different parts and execute each one as a task. That way the task is executed as soon as processor becomes idle. You may want to reference http://docs.tinyos.net/index.php/Modules_and_the_TinyOS_Execution_Model for more details. There have been some attempts at preemption: http://www.tinyos.net/scoop/story/2007/7/9/10921/69539 and TOSTHREADS are among them if preemption is required for your purposes. -Paul On 1/2/2010 12:12 PM, Mido wrote: > Hi, > > > I'd always assumed that events can preempt events. > > For example, in the below code, the event AMSend.sendDone should preempt > Timer1.fired (as Timer1.fired runs for a long time). > > However, this is not happening. > Things do not change when I move the code inside Timer1.fired to a task, and > post this task from Timer1.fired. > > So, do events preempt other events? > > One more question: > Section 1.2.1 of the TinyOS programming book (2nd edition), mentions > "Low-level interrupt code". > How can I find the interrupt code that is related certain events such as > Timer.fired, AMSend.sendDone, and Sensor.readDone. > > Thanks. > > > event void Boot.booted() {call AMControl.start(); } > event void AMControl.startDone(error_t err) {if (err == SUCCESS) {call > Timer0.startPeriodic(900); call Timer1.startPeriodic(1000); } else {call > AMControl.start();} } > event void AMControl.stopDone(error_t err) { } > event void Timer0.fired() > { > if (!busy) > { > BlinkToRadioMsg* btrpkt = (BlinkToRadioMsg*)(call > Packet.getPayload(&pkt, NULL)); > btrpkt->nodeid = TOS_NODE_ID; > btrpkt->counter = counter; > if (call AMSend.send(AM_BROADCAST_ADDR,&pkt, > sizeof(BlinkToRadioMsg)) == SUCCESS) {busy = TRUE;} > } > } > event void AMSend.sendDone(message_t* msg, error_t error) { if (&pkt == > msg) {busy = FALSE;}} > event void Sensor.readDone(error_t result, uint16_t data) {} > > event void Timer1.fired() > { > t=269;p=40; > for (t=0;t<100;t++){for (i=0;i<10000;i++){n+=p;n=0;n*=p+5;}}call > Leds.led0Toggle(); > } > > _______________________________________________ > Tinyos-help mailing list > Tinyos-help@millennium.berkeley.edu > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > _______________________________________________ Tinyos-help mailing list Tinyos-help@millennium.berkeley.edu https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
