wait() suspends the thread or clocked thread process instance from which it is called for the very next occasion on which that process instance is resumed, and for that occasion only. The dynamic sensitivity is determined by the arguments passed to function wait (Example clock).

A call to the function wait with an empty argument list or with a single integer argument shall use the static sensitivity of the process instance. This is the only form of wait permitted within a clocked thread process. A call to the function wait with one or more non-integer arguments shall override the static sensitivity of the process instance.

When calling function wait with a passed-by-reference parameter, the application shall be obliged to ensure that the lifetimes of any actual arguments passed-by-reference extend from the time the function is called to the time the function call completes, and moreover in the case of a parameter of type sc_time, the application shall not modify the value of the actual argument during that period.

Note :It is error to call function wait from a method process.

wait takes parameter, some of which are listed below

• wait() : Wait for the sensitive list event to occur.
• wait(int) : Wait for n events to occur, events are the one in sensitive list.
• wait(event) : Wait for the event mentioned as parameter to occur.
• wait(double,sc_time_unit) : Wait for specified time.
• wait(double,sc_time_unit, event) : Wait for specified time or event to occur.

  1 #include <systemc.h>
  2 
  3 SC_MODULE (wait_example) {
  4   sc_in<bool> clock;
  5 
  6   sc_event  e1;
  7   sc_event  e2;
  8 
  9   void do_test1() {
 10     while (true) {
 11       // Wait for posedge of clock
 12       wait();
 13       cout << "@" << sc_time_stamp() <<" Starting test"<<endl;
 14       // Wait for 5 posedge of clock
 15       wait(5);
 16       cout << "@" << sc_time_stamp() <<" Triggering e1"<<endl;
 17       // Trigger event e1
 18       e1.notify(5,SC_NS);
 19       // Wait for 3 NS
 20       cout << "@" << sc_time_stamp() <<" Time before wait 3 ns"<<endl;
 21       wait(3, SC_NS);
 22       cout << "@" << sc_time_stamp() <<" Time after wait 3 ns"<<endl;
 23       // Wait for event e2
 24       wait(e2);
 25       cout << "@" << sc_time_stamp() <<" Got Trigger e2"<<endl;
 26       // Wait for posedge of clock
 27       wait(30);
 28       cout<<"Terminating Simulation"<<endl;
 29       sc_stop(); // sc_stop triggers end of simulation
 30     }
 31   }
 32 
 33   void do_test2() {
 34     while (true) {
 35       // Wait for event e2
 36       wait(e1);
 37       cout << "@" << sc_time_stamp() <<" Got Trigger e1"<<endl;
 38       // Wait for 3 posedge of clock
 39       wait(20);
 40       cout << "@" << sc_time_stamp() <<" Triggering e2"<<endl;
 41       // Trigger event e2
 42       e2.notify();
 43       // Wait for either 20ns or event e1
 44       wait(20,SC_NS,e1);
 45       cout << "@" << sc_time_stamp() <<" Done waiting for 20ns or event e1"<<endl;
 46     }
 47   }
 48 
 49   SC_CTOR(wait_example) {
 50     SC_CTHREAD(do_test1,clock.pos());
 51     SC_CTHREAD(do_test2,clock.pos());
 52   }
 53 }; 
 54 
 55 int sc_main (int argc, char* argv[]) {
 56   sc_clock clock ("my_clock",1,0.5);
 57 
 58   wait_example  object("wait");
 59     object.clock (clock.signal());
 60 
 61   sc_start(0); // First time called will init schedular
 62   sc_start();  // Run the simulation till sc_stop is encountered
 63   return 0;// Terminate simulation
 64 }

 @1 ns Starting test
 @6 ns Triggering e1
 @6 ns Time before wait 3 ns
 @9 ns Time after wait 3 ns
 @11 ns Got Trigger e1
 @31 ns Triggering e2
 @32 ns Got Trigger e2
 @51 ns Done waiting for 20ns or event e1
 Terminating Simulation
 SystemC: simulation stopped by user.

Copyright © 1998-2014

Deepak Kumar Tala - All rights reserved

Do you have any Comment? mail me at:deepak@asic-world.com