Module's parameter initialization troubles

SystemVerilog
,
1

Good day! English is not my native language so first of all sorry for mistakes.

I have the following code:

package my_pkg;

    class helper #(
        parameter seed = 0
    );
        
    static function int GetRand();
        return seed + 10;
    endfunction

    endclass : helper

endpackage : my_pkg

module myModule #(
    parameter myParam = 0
);

    initial begin
        $display("My value = %d", myParam);
    end

endmodule : myModule

module test_class #(
);

    myModule #(
        .myParam(my_pkg::helper #(.seed(5))::GetRand())
    ) i_myModule ();

endmodule : test_class

Real task is simplified to this short example. While launching simulation with QuestaSim 2019.2 i’m getting following errors:
** Error: …/…/…/…/bpl_test_debug.srcs/sources_1/new/TEST.sv(54): External function ‘<class-spec#1>::GetRand’ may not be used in a constant expression.
** Error: …/…/…/…/bpl_test_debug.srcs/sources_1/new/TEST.sv(54): The expression for a parameter actual associated with the parameter name (‘myParam’) for the module instance (‘i_myModule’) must be constant.

It works if i use class without parameters, but actually i have to pass at least one to be able to return from static function array with parametrized length.

May be someone can suggest any workaround?

2

In reply to DonRumata:

Without knowing how you plan to use myParam and why it needs to be a parameter, it is difficult to suggest a workaround.

I believe this code should be legal, but many tools do not support it. This Mentor/Siemens EDA sponsored public forum is not for discussing tool specific usage or issues. Please read your tool’s user manual or contact your tool vendor directly for support.

3

In reply to dave_59:

Thank you for fast reply!

I’m going to pass myParam to initialize registers array inside module. It’s simplified version, but in a real case it should have type logic [REG_NUM * REG_WIDTH - 1 : 0] and i want to get it from function which filling it.

Got it, i’ll check

4

In reply to DonRumata:

The code you wrote could easily be rewritten as

package my_pkg;
function int GetRand(int seed);
  return seed + 10;
endfunction 
endpackage : my_pkg
 
module myModule #(
    parameter myParam = 0
);
    logic [myParam:0] data;
    initial begin
        $display("My value = %d", myParam);
    end
 
endmodule : myModule
 
module test_class #(
);
 
    myModule #(
      .myParam(my_pkg::GetRand(5))
    ) i_myModule ();
 
endmodule : test_class
5

In reply to dave_59:

That’s it. But this example is just too simplified

package my_pkg;

    class helper #(
        parameter p_WIDTH = 16,
        parameter p_COUNT = 2
    );

    typedef logic [p_COUNT - 1 : 0] [p_WIDTH - 1 : 0] ret_t;

    static function ret_t GetRand(int value);
        automatic ret_t result;

        for (int i = 0; i < p_COUNT; ++i) begin
            result[i] = value * i;
        end
    endfunction

    endclass : helper

endpackage : my_pkg

module myModule #(
    parameter                                     p_WIDTH = 16,
    parameter                                     p_COUNT = 2,
    parameter [p_COUNT - 1 : 0] [p_WIDTH - 1 : 0] p_INIT  = '{default: 0}
);

    // other module i can't edit
    otherModule #(
        ......
        .p_INIT(p_INIT),
        ......
    ) (
      .....
    )

endmodule : myModule

module test_class
    import my_pkg::*;
#();

    localparam p_WIDTH = 16;
    localparam p_COUNT = 2;
    localparam p_STEP  = 6;

    typedef helper#(.p_WIDTH(p_WIDTH), .p_COUNT(p_COUNT)) helper_t;

    myModule #(
        .p_WIDTH(p_WIDTH                  ),
        .p_COUNT(p_COUNT                  ),
        .p_INIT (helper_t::GetRand(p_STEP))
    ) i_myModule (
        .....
    );

endmodule : test_class

In real case i need something like this