How to ground bus access port?

[katang]

I have some modules of the same class, and only part of the instances needs access to a certain bus, the others should not be linked to the bus. Of course I know during the setup phase, which ones should and which ones should not.  The ones that should connect, I can connect, it works fine. At the same time, for the others, I would like to tell the ports they should not be connected. Is there some method to do so (i.e. I want to avoid 'complete binding failed', not more) . Or, shall I subclass a new module class for those modules, with the only difference that they have an extra port? Or, shall I give those modules a very low priority (they surely will not use the bus), and connect them formally to the bus? (maybe it causes unneeded wiring)

I.e.

[Roman Popov]

Other option is to pass some flag to constructor

struct my_module : sc_module 
{
    std::unique_ptr< bus_port  >  bus_slave;
  
    my_module(sc_module_name, bool has_slave_port) 
    {
        if (has_slave_port) 
        {
            bus_slave = std::make_unique<bus_port>("bus_slave");
        }
    }

 

For SystemC 2.4 there is a sc_optional<T> class proposal that will allow to create ports "on demand" at any time during elaboration.

 

[katang]

Sorry, I forgot to mention: I have a master port, like this

 sc_port<scBus_blocking_if> bus_port;

If I understand the point correctly, I shall use pointer, that (still within the constructor) I can change from the default null.

 

 

[Roman Popov]

I mean if you don't need to connect the port, then don't create the port. This is the idea.

[katang]

You are absolutely right, thank you. From point of view of programming, it is OK. Till now, however, I never thought about ports that one create them with new 🙂