Best way to pass parameters trough modules

[João Paulo]

I'm creating a parametrized Network on Chip on SystemC, and i need to pass the position of each router by parameters, so i tried templates but they don't accept variables, only const values, for now, i'm using the sc_in port, but i'm trying to not use this, anyone now's other ways?

[Eyck]

Why not use constructor prameters? Another option would be cci_params. Via the broker they can be given a value before they are created. So you can use them in contructor bodies....

[maehne]

As @Eyck suggested, constructor parameters should fit best your needs. You can even give them default values if it is sensible. If the number of parameters grows, grouping them in a struct may become handy. Its members can be default-initialised and you can override them with assignments before passing the whole struct to the module constructor. Personally, I like to first check for consistency and legal range for these parameters in the constructor / member function to which I pass this struct, e.g., by using assertions before actually using them for describing any behaviour/internal structure.

[songlin941111]

Hello,

I have a similar preoblem ：

I define a parameter NUM in My_module : static const int NUM = 7;

And this parameter is for port : sc_in< sc_uint<NUM> > a{"a"};

Then i would like to initialize this parameter in module constructor like this:
SC_CTOR(My_module ); My_module (const sc_module_name& name, int NUM): sc_module(name), NUM(NUM) {}

But it doesn't work, because of the error :
error: 'const int My_module::NUM' is a static data member; it can only be initialized at its definition

It seems like that sc_unit<> accepts onlt static parameter, and constructor parameter doesn't accept static...

Do you have some good advise for this parameter transfer need, pls?

[David Black]

The discussed issue indicates a lack of proper understanding and mastery of C++ by the originators of this thread. Both @João Paulo and @songlin941111 need to obtain a better education in C++. There are many ways to do this, but it is fundamental to success with SystemC. SystemC is not C; although, I find many folks don't understand this. You can indeed understand a lot of SystemC with just a C background, but you truly do not understand SystemC until you fully understand C++.

C++ templates are a compile-time abstraction. As @Eyck and @maehne suggest, constructor arguments are the right way to go, which probably means using some base classes (e.g., sc_int_base or sc_uint_base -- see IEEE-1666-2011 section 7.5 and following) rather than templates. The use of CCI would also be appropriate to augment this.