Example Test Bench Using Interface and Classes

I'm sharing this code, which is an example of using an SV Interface to transmit a class of data & functions to a DUT. // Todd Mackett Cadence Design Systems // ncverilog class_across_interface.sv +sv +linedebug +gui // tested wtih IUS5.83s1 /* top-------------------------- | test --->interface---->dut | |----------------------------- */ package mypack; class some_class; //class is the rudimentry data container int some_int; real some_real; protected string some_string; // needs to be protected for IUS5.83 function void set_data (int i, real r, string s); some_int =i; some_real = r; some_string = s; endfunction task get_data(output int i, output real r, output string s); i = some_int; r = some_real; s = some_string; endtask function void print_data(); $display("Int: %d, Real: %f, String: %s", some_int, some_real, some_string); endfunction endclass endpackage // ------ // This channel is an interface that is a queue of classes interface myIF; import mypack::*; event some_event; some_class some_classQ[$]; function int some_classQ_size(); return some_classQ.size(); endfunction task push_class_in_Q(input some_class Qin); some_classQ.push_front(Qin); endtask task pop_class_out_Q(output some_class Qout); Qout = some_classQ.pop_back(); endtask endinterface // ----------------- module top(); int top_int; reg clk = 'b1; initial forever clk = #10 ~clk; // system clk myIF myIFi(); // instantiate interface test testi(clk, myIFi); dut duti(clk, myIFi); endmodule // -------------- // The test module create a class of information and puts it in the // channel (a queue in the interface) module test (input clk, myIF myIFi); import mypack::*; int i; real r; string s; initial #200 $finish; some_class top_class; always @(posedge clk) begin top_class = new; // randomize the data per class object i = $urandom_range(5,1); randcase 1: r = 3.14; 1: r = 123.456; 1: r = -943.825; endcase randcase 1: s = "IUS SystemVerilog"; 1: s = "Cadence"; 1: s = "Who needs VHDL?"; endcase top_class.set_data(i, r, s); // set the values into class myIFi.push_class_in_Q(top_class); // transmit the class -> myIFi.some_event; // cause the event end endmodule // ------------- // The dut module consumes the class when the event is valid // and displays its contents as it comes across the interface module dut (input clk, myIF myIFi); import mypack::*; some_class dut_class =new; always @(myIFi.some_event) // process event begin $display("\nQueue Size %d",myIFi.some_classQ_size() ); myIFi.pop_class_out_Q(dut_class); dut_class.print_data(); end endmodule