The problem of reading the custom structure is reasonable.

[mariaantoanet]

Hello friends.
I have questions to ask for your help.

I have a struct defined as 

struct pixel {
    sc_uint<8> r;
    sc_uint<8> g;
    sc_uint<8> b;
};
Then I try to pass actual pixel values to the ports, defined as pixel data type in main.cpp

sc_signal<pixel> p1;
sc_signal<pixel> p2;

p1.write(pixel(1, 2, 3));
p2.write(pixel(4, 5, 6));

But it seems p1.write() and p2.write() didn't initialize p1 and p2 correctly as I still see they don't have the expected pixel values (1,2,3) and (4,5,6).

Do I need to use sc_interface to pass this customized data type around?

Thank's a lot!

[David Black]

sc_core::sc_signal<T> requires that you define the following:

T::operator=(const T&)

T::operator==(const T&)

ostringstream&. operator<<( ostringstream&,const T& )

 

[Andy Goodrich]

I addition to the requirements mentioned by David, you need  to define a constructor with 3 arguments for pixel, something like:

 

struct pixel {

    sc_dt::sc_uint<8> r;

    sc_dt::sc_uint<8> g;

    sc_dt::sc_uint<8> b;

    pixel() :r(0), g(0), b(0) {}

    pixel( const sc_dt::sc_uint<8>& r_init, const sc_dt::sc_uint<8>& g_init, const sc_dt::sc_uint<8>& b_init ) : r(r_init), g(g_init), b(b_init) {}

};

[karthickg]

Quote

But it seems p1.write() and p2.write() didn't initialize p1 and p2 correctly as I still see they don't have the expected pixel values (1,2,3) and (4,5,6).

I'm guessing you are trying to read the signal values immediately after calling write(). That won't return the values just written due to how update semantics work with primitive channels in SystemC.

To make sure this is the cause of confusion, you can try creating a thread in your model where the signal values are written and read back after a delta-cycle wait:

SC_MODULE(some_module)
{
   sc_signal<pixel> p1;
   sc_signal<pixel> p2;

   void some_thread() {
     p1.write(pixel(1, 2, 3));
     p2.write(pixel(4, 5, 6));
     // Read and print p1 and p2
     // Values won't be updated here
     wait(0, SC_NS);
     // Read and print p1 and p2
     // Values will be updated here
};