verilator/examples/make_protect_lib/secret_impl.v

// DESCRIPTION: Verilator: --protect-lib example secret module
//
// This file ONLY is placed into the Public Domain, for any use,
// without warranty, 2019 by Todd Strader.

// This module will be used as libsecret.a or libsecret.so without
// exposing the source.
module secret_impl(
		   input [31:0]        a,
		   input [31:0]        b,
		   output logic [31:0] x,
		   input 	       clk);

   logic [31:0] 		       accum_q = 0;
   logic [31:0] 		       secret_value = 9;

   initial $display("%m: initialized");

   always @(posedge clk) begin
      accum_q <= accum_q + a;
      if (accum_q > 10)
        x <= b;
      else
        x <= a + b + secret_value;
   end

endmodule