sc_event_queue

[rahuljn]

Hi All

 

I see immediate notification is not possible with sc_event_queue objects.

Is there some specific reason for this.

 

Thanks

[David Black]

I don't recall a strong reason for this, but I am not sure I see a use either. If you need immediate notification then use sc_event or you can always use a time delay of SC_ZERO_TIME.

 

The purpose of sc_event_queue was to be able to guarantee that every notification would be seen by any interested process. If you allowed for immediate notification, that would no longer be true because two notifications in a row would result in a lost notification. In other words:

SC_MODULE(Top) {
  sc_event_queue eq;

  SC_CTOR(Top) {
    SC_THREAD(sending_thread);
    SC_THREAD(watching_thread);
  }

  void sending_thread(void) {
    for(size_t i=0; i!=4; ++i) {
      eq.notify(); //< illegal syntax used for illustration
      eq.notify(); //< illegal syntax used for illustration -- **this would never be observed**
      wait(SC_ZERO_TIME);
    }
    sc_stop();
  }

  void watching_thread(void) {
    for(; {
      wait(eq);
      SC_REPORT_INFO("","Observed eq");
    }
  }
};

[rahuljn]

_{Thanks David.}

 

_{Any way there is a hack, You can use the following to implement immediate notification with sc_event_queue}

_{const_cast<sc_event*>(&eq.default_event())->notify();}

 

_Thanks

[David Black]

But why are you needing an immediate notification?

Do you realize that this may cause some processes to never see the event?

[mohitnegi]

Hello guyz

i have some issue related to this

#include "systemc.h"

class test : public sc_module {
    public :
    sc_event_queue events;
    SC_HAS_PROCESS(test);
    test(sc_module_name name){
        SC_THREAD(thread1);
        SC_THREAD(thread2);
    }
    void thread1(){
        //wait(event_1);
        events.notify(SC_ZERO_TIME);
        events.notify(SC_ZERO_TIME);
    }

    void thread2(){
        while(1){
            wait(events.default_event());
            cout<<"event arrived"<<endl;
        }
    }
};

Now this is printing " event arrived " twice ...

Now but in actual there is also a wait (commented part) in code ...

now when i am actualling implementing it , it is running only once ...i dont understand the reason for this ......

[apfitch]

I don't understand the code. The commented code should not compile as you haven't declared event_1

 

Alan

[dakupoto]

Hello guyz

i have some issue related to this

#include "systemc.h"

class test : public sc_module {
    public :
    sc_event_queue events;
    SC_HAS_PROCESS(test);
    test(sc_module_name name){
        SC_THREAD(thread1);
        SC_THREAD(thread2);
    }
    void thread1(){
        //wait(event_1);
        events.notify(SC_ZERO_TIME);
        events.notify(SC_ZERO_TIME);
    }

    void thread2(){
        while(1){
            wait(events.default_event());
            cout<<"event arrived"<<endl;
        }
    }
};

Now this is printing " event arrived " twice ...

Now but in actual there is also a wait (commented part) in code ...

now when i am actualling implementing it , it is running only once ...i dont understand the reason for this ......

Sir,

It is not clear what is the final goal of this module.

Simply looking at the stated results, the module is

doing what it is supposed to do. In 'thread1', with 

the 'wait' commented out, at zero time two events

are inserted into the event queue, and 'thread2'

responds to them.

When the 'wait' in 'thread1' is activated, then that

thread goes on waiting for 'event_1', while 'thread2'

responds to some random default event, and then

goes on waiting for 'default_event' s in the event

queue.

How is 'event_1' getting generated -- in some other

module perhaps ? Please first identify what the 

modules are supposed to do, otherwise there will

more confusion. Hope that helps.