In this work I show how to build a reference model in systemc using queues, from C++ STD.

1. Link to the main page of this work. This page explains the monitor used in this project.


2. The monitor of this project has multiple functions. In small project like this, I decided to have this monitor to collect data, calculate expected, store results in a scoreboard and also check the data, which is output by the DUT, after some latency (four clock cycles).


3. To implement a scoreboard, I use queues from C++ STD.
   The scoreboard is merely a queue (list in specman) of complex numbers, represented as two-dimensional Cartesian coordinate.
   
   class scoreboard {
     public:
     signed oa;
     signed ob;
     scoreboard(signed x, signed y) {//constructor
       oa=x;
       ob=y;
     }
   };
   


4. Same as the DUT uses sign extension, the monitor does it as well.
   
   ...
     void sign_ext_p() {
       while(true) {
         sc_int<6> add_tmpa;
         sc_int<6> add_tmpb;
         sc_int<6> add_tmpc;
         sc_int<6> add_tmpd;
         a.read().range(7,7) == 0 ? add_tmpa=0 : add_tmpa=63;
         b.read().range(7,7) == 0 ? add_tmpb=0 : add_tmpb=63;
         c.read().range(7,7) == 0 ? add_tmpc=0 : add_tmpc=63;
         d.read().range(7,7) == 0 ? add_tmpd=0 : add_tmpd=63;
         ex_a.write( (add_tmpa, a.read()) );
         ex_b.write( (add_tmpa, b.read()) );
         ex_c.write( (add_tmpa, c.read()) );
         ex_d.write( (add_tmpa, d.read()) );
         wait();
       }
     }
   ...
   


5. The expected calculation as well as scoreboard operation is shown below:
   
   ...
   void logic_p() {
     while (!scbd_l.empty()) scbd_l.pop(); //clear after reset is de-asserted
     //cout << "scbd_l was cleared " << " at " << sc_time_stamp() << endl;
     while(true) {
       sc_int<14> add_tmpa;
       sc_int<14> add_tmpb;
       add_tmpa = (ex_a.read()*ex_c.read()) - (ex_b.read()*ex_d.read());
       add_tmpb = (ex_a.read()*ex_d.read()) + (ex_b.read()*ex_c.read());
       //cout << "a=" << ex_a << " b=" << ex_b << " c=" << ex_c << " d=" << ex_d << " ";
       //cout << add_tmpa << " " << add_tmpb << " at " << sc_time_stamp() << endl;
   
       //add to scoreboard
       scbd_tmp = new scoreboard((signed)add_tmpa, (signed)add_tmpb);
       //
       if(scbd_l.size() == 2) {
         scoreboard *scbd_chk;
         scbd_chk=&scbd_l.front();
         e_oaq.write(scbd_chk->oa);
         e_obq.write(scbd_chk->ob);
         scbd_l.pop();
         cmp_ok.write(1);
         if(e_oaq.read() != oa.read()) {
           cmp_ok.write(0);
           cout << "a error exp " << e_oaq.read() << " got " << oa.read() << " at " << sc_time_stamp() << endl;
         }
         if(e_obq.read() != ob.read()) {
           cmp_ok.write(0);
           cout << "b error exp " << e_obq.read() << " got " << ob.read() << " at " << sc_time_stamp() << endl;
         }
       } else {
         cmp_ok.write(1);
       }
       scbd_l.push(*scbd_tmp);
       wait();
     }
   }
   ...