SystemC：未使用 or 固定値端子の処理

How to terminate unused ports of modules in the port binding?

SystemCモデルの接続において、Verilog HDLのように
未使用端子を簡単に処理出来ません。
VHDLのように何かしらを接続する必要があります。

つまり、以下のようなコードになります。

#include <systemc.h>

SC_MODULE( hoge ){
  sc_in <int>  a;
  sc_in <int>  b;
  sc_in <int>  c;

  sc_out<int>  out;
  sc_out<bool> irq;

  void process(){
    out = a + b + c;
    irq = ((a+b+c) > 10)? 1 : 0;
  }

  SC_CTOR( hoge )
  {
    SC_METHOD( process );
    sensitive << a << b << c ;
  }
};

int sc_main( int argc, char* argv[] ) {

  sc_signal<int>  sig_a;
  sc_signal<int>  sig_b;
  sc_signal<int>  sig_c;
  sc_signal<int>  sig_out;
  sc_signal<bool> sig_irq;

  hoge uhoge("hoge");
  uhoge.a(sig_a);
  uhoge.b(sig_b);
  uhoge.c(sig_c);
  uhoge.out(sig_out);
  uhoge.irq(sig_irq);

  sig_a = 1;
  sig_b = 2;
  sig_c = 3;

  sc_start(1.0, SC_PS);

  cout << "a = " ; sig_a.print(); cout << ", ";
  cout << "b = " ; sig_b.print(); cout << ", ";
  cout << "c = " ; sig_c.print(); cout << ", ";
  cout << "out = "; sig_out.print(); cout << ", ";
  cout << "irq = "; sig_irq.print(); cout << endl;

  sig_a = 3;
  sig_b = 4;
  sig_c = 5;

  sc_start(1.0, SC_PS);

  cout << "a = " ; sig_a.print(); cout << ", ";
  cout << "b = " ; sig_b.print(); cout << ", ";
  cout << "c = " ; sig_c.print(); cout << ", ";
  cout << "out = "; sig_out.print(); cout << ", ";
  cout << "irq = "; sig_irq.print(); cout << endl;

  return 0;
}

実行結果

a = 1, b = 2, c = 3, out = 6, irq = 0
a = 3, b = 4, c = 5, out = 12, irq = 1

さて、これは非常に手間だと思います。
わざわざ sc_signalを宣言し、値を代入する。
なので、そのような手間を省くために共通化したクラス(部品)を作ればいいのです。

オープン端子(output側)

static struct {

  template < typename T >
  operator sc_core::sc_signal_inout_if<T> & () const
  {
    return *(new sc_core::sc_signal<T>(sc_core::sc_gen_unique_name("vh_open")));
  }

} const vh_open = {};

固定値(input側)

template<typename T>
sc_core::sc_signal_in_if<T> const &
vh_const( T const & v ) // keep the name consistent with vh_open
{
  // Yes, this is an (elaboration-time) memory leak.  You can avoid it with some extra effort
  sc_core::sc_signal<T>* sig_p = new sc_core::sc_signal<T>( sc_core::sc_gen_unique_name("vh_const") );
  sig_p->write( v );
  return *sig_p;
}

記述全体はこちらになります。

#include <systemc.h>

//---------------------------------------------//
static struct {

  template < typename T >
  operator sc_core::sc_signal_inout_if<T> & () const
  {
    return *(new sc_core::sc_signal<T>(sc_core::sc_gen_unique_name("vh_open")));
  }

} const vh_open = {};
//---------------------------------------------//
template<typename T>
sc_core::sc_signal_in_if<T> const &
vh_const( T const & v ) // keep the name consistent with vh_open
{
  // Yes, this is an (elaboration-time) memory leak.  You can avoid it with some extra effort
  sc_core::sc_signal<T>* sig_p = new sc_core::sc_signal<T>( sc_core::sc_gen_unique_name("vh_const") );
  sig_p->write( v );
  return *sig_p;
}
//---------------------------------------------//

SC_MODULE( hoge ){
  sc_in <int>  a;
  sc_in <int>  b;
  sc_in <int>  c;

  sc_out<int>  out;
  sc_out<bool> irq;

  void process(){
    out = a + b + c;
    irq = ((a+b+c) > 10)? 1 : 0;
  }

  SC_CTOR( hoge )
  {
    SC_METHOD( process );
    sensitive << a << b << c ;
  }
};

int sc_main( int argc, char* argv[] ) {

  sc_signal<int>  sig_a;
  sc_signal<int>  sig_b;
  sc_signal<int>  sig_c;
  sc_signal<int>  sig_out;
  sc_signal<bool> sig_irq;

  hoge uhoge("hoge");
  uhoge.a(sig_a);
  uhoge.b(sig_b);
  uhoge.c(vh_const(42)); // const value
  uhoge.out(sig_out);
  uhoge.irq(vh_open);  // open

  sig_a = 1;
  sig_b = 2;
  sig_c = 3;

  sc_start(1.0, SC_PS);

  cout << "a = " ; sig_a.print(); cout << ", ";
  cout << "b = " ; sig_b.print(); cout << ", ";
  cout << "c = " ; sig_c.print(); cout << ", ";
  cout << "out = "; sig_out.print(); cout << ", ";
  cout << "irq = "; sig_irq.print(); cout << endl;

  sig_a = 3;
  sig_b = 4;
  sig_c = 5;

  sc_start(1.0, SC_PS);

  cout << "a = " ; sig_a.print(); cout << ", ";
  cout << "b = " ; sig_b.print(); cout << ", ";
  cout << "c = " ; sig_c.print(); cout << ", ";
  cout << "out = "; sig_out.print(); cout << ", ";
  cout << "irq = "; sig_irq.print(); cout << endl;

  return 0;
}

実行結果はこちら

a = 1, b = 2, c = 3, out = 45, irq = 0
a = 3, b = 4, c = 5, out = 49, irq = 0

ちゃんと出来ていますね！