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// Learn with Examples, 2020, MIT license
#include <systemc>
using namespace sc_core;

SC_MODULE(QUEUE) {
  sc_event e;
  sc_event_queue eq;
  SC_CTOR(QUEUE) {
    SC_THREAD(trigger);
    SC_THREAD(catch_e);
    sensitive << e; // catch_e() will be triggered by event e
    dont_initialize(); // don't run cach_e() during initialization phase
    SC_THREAD(catch_eq);
    sensitive << eq; // cach_eq() will be triggered by event queue eq
    dont_initialize(); // don't run catch_eq() during initialization phase
  }
  void trigger() {
    while (true) {
      e.notify(2, SC_SEC); // trigger e afer 2 s
      e.notify(1, SC_SEC); // trigger e after 1 s, replaces previous trigger
      eq.notify(2, SC_SEC); // trigger eq after 2 s
      eq.notify(1, SC_SEC); // trigger eq after 1 s, both triggers available
      wait(10, SC_SEC); // another round
    }
  }
  void catch_e() {
    while (true) {
      std::cout << sc_time_stamp() << ": catches e" << std::endl;
      wait(); // no parameter --> wait for static sensitivity, i.e. e
    }
  }
  void catch_eq() {
    while (true) {
      std::cout << sc_time_stamp() << ": catches eq" << std::endl;
      wait(); // wait for eq
    }
  }
};

int sc_main(int, char*[]) {
  QUEUE queue("queue"); // instantiate object 
  sc_start(20, SC_SEC); // run simulation for 20 s
  return 0;
}

// Result:
1 s: catches e
// e scheduled at 2 s is not triggered
1 s: catches eq
// eq triggered at both 1 s and 2 s
2 s: catches eq
11 s: catches e
// e scheduled at 12 s is not triggered
11 s: catches eq
12 s: catches eq