Jump to content
Roman Popov

Why [ ] operator is not overloaded for sc_signal ?

Recommended Posts

A follow-up question for

http://forums.accellera.org/topic/5443-vector-declaration/

 

Why square brakets are not overloaded for sc_signal class?  In case underling datatype allows bit-level access, it seems it would be handy to allow it for signals?

 

Looks like there is no technical limitation to do this, here is an example:

#include <systemc.h>

template< class T, sc_writer_policy POL = SC_DEFAULT_WRITER_POLICY >
struct my_sc_signal : public sc_signal<T, POL> {
    typedef my_sc_signal<T,POL>          this_type;
    typedef sc_signal<T, POL>            base_type;

    explicit my_sc_signal( const char* name_)  : base_type( name_ ){}

    struct signal_writer_helper {
        signal_writer_helper (this_type &s, size_t i) : sig(s), id(i) {}

        template <typename AT>
        void operator = ( const AT& val_ )
        {
            bool value_changed = !( sig.m_cur_val[id] == val_ );

            sig.m_new_val[id] = val_;
            if( value_changed )
                sig.request_update();
        }

        this_type &sig;
        size_t id;

    };

    signal_writer_helper operator [](size_t i) {
        return signal_writer_helper(*this, i);
    }

};


SC_MODULE(test) {

    static const int BUS_WIDTH = 10;
    my_sc_signal<sc_uint<BUS_WIDTH> > test_sig{"test_sig"};

    SC_CTOR(test) {
        SC_THREAD(master_thread);
        SC_METHOD(slave_method);
        sensitive << test_sig;
    }

    void master_thread() {
        for (int i = 0; i < BUS_WIDTH; ++i) {
            test_sig[i] = 1;
            wait(1, SC_NS);
        }

        for (int i = 0; i < BUS_WIDTH; ++i) {
            test_sig[i] = 1;
            wait(1, SC_NS);
        }

        sc_stop();
    }

    void slave_method() {
        cout << "New signal value is: " << test_sig.read() << endl;
    }

};

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

    test test_inst("test_inst");
    sc_start();
    return 0;

}

Share this post


Link to post
Share on other sites

There is an ASSIGN implementation proposal in:

http://nascug.org/events/17th/black_cpp11_2_27_2012.pdf

 

 

So with bit level access to sc_signals I can imagine something like:

 

ASSIGN( addr_sig, a_sel_sig = addr_sig[0] );

ASSIGN( addr_sig, b_sel_sig = addr_sig[1] );

ASSIGN( addr_sig, c_sel_sig = addr_sig[2] );

 

or even

ASSIGN( addr_sig[0], a_sel_sig = addr_sig[0] );

ASSIGN( addr_sig[1], b_sel_sig = addr_sig[1] );

ASSIGN( addr_sig[2], c_sel_sig = addr_sig[2] );

 
if sc_signal[] returns something with event capabilities
 
Highly desired for Synthesizable SystemC.
 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...