Course : Systemverilog Verification 6 : L5.1 : Observed Region

[00:00:01]observed region in systematic simulation agency so the main purpose of observed region is to evaluate concurrent assertions so this is an assertion specific region and there are two types of assignments assertions in system will look which are immediate assertions and concurrent assertions and the immediate assertions will be evaluated in the active region set and inconcurrent assertion will be evaluated in the observed region set and also note that this evaluation of concurrent assertions will be taking place with the values that is sampled in the pre-bond region so you have already seen in the prepone region is place where all the variables that is used along with the concurrent assertions are getting sampled and that value will be used to evaluate the concurrent assertions in the observed region that that means if i told that variable is getting updated between the prepon region and observed region that is any of the active region set then that effect will not be taking uh consider in in the evaluation of this current time slots concurrent assertions and based on the pass or fail condition of the concurrent assertion it can also schedule a process uh along with this say for example if an assertion is failing you know you can call as a task in systematic and if that kind of scheduling is happening it will be put into the reactive region and so no none of those uh those activities should be happening in the upside region observed it is dedicated only for evaluation of concurrent assertions and apart from that one more thing will happen in observed region that is the triggering of clocking block so you have an um expression with you have a clocking block with which is regarding triggering at the positive edge of clock and if that clock was getting changed from zero to one in the active region so uh the trigger event is happening in the in the time region and in this current times route and the actual triggering of this clocking work will happen in the observed region so if a clocking block is getting triggered then uh in the same time slot its output can be driven into the simulation and uh you have already seen that there is a feedback possible from observed region so if you look at the previous diagram which is showing all the time regions from the observed region it is possible to go back to active region so from the observation either it can go to active within again with a feedback loop or it can go to the reactive reactive region set so we have already discussed that if there's a password fail condition uh associated with the congruent assertion evaluation that will be scheduled to this reactive regains it and when this feedback will happen so this feedback will happen only if there is an expect statement in the concurrent assertion so you can write a concurrent expression along with an expect statement so if the statement is written with an expert keyword then only this feedback from observed region to the active region will happen and again that will happen only if this expect statement is written in a module if it is written in a program block it won't happen so this feedback will happen only in in case of an expect statement that is written in a module and this statement is very rarely used in um simulation i mean system builder coding so usually the feedback from optional region to the active region will not happen in normal test benches and as we already discussed if there is another pass or fail event along with happening along with the valuation of the concurrent assertions those will be scheduled to the next set of region which is the reactive set re re-regen set so from here if a pass of fail condition is specifying some more events in this time slot it will be evaluated in the rear regions and that is the name these regions are getting called re-region so all these actions that was happening here will be again evaluated so it won't go back to this active region set but the same set of capabilities are given in in the real region a reactive the inactive ray nba and we will learn about these three reagents in the next section