| // Copyright 2020-2022 F4PGA Authors | 
 | // | 
 | // Licensed under the Apache License, Version 2.0 (the "License"); | 
 | // you may not use this file except in compliance with the License. | 
 | // You may obtain a copy of the License at | 
 | // | 
 | //     http://www.apache.org/licenses/LICENSE-2.0 | 
 | // | 
 | // Unless required by applicable law or agreed to in writing, software | 
 | // distributed under the License is distributed on an "AS IS" BASIS, | 
 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | 
 | // See the License for the specific language governing permissions and | 
 | // limitations under the License. | 
 | // | 
 | // SPDX-License-Identifier: Apache-2.0 | 
 |  | 
 | (* blackbox *) | 
 | module box( | 
 |     (* invertible_pin="INV_A" *) | 
 |     input  wire [1:0] A, | 
 |     input  wire [1:0] B, | 
 |  | 
 |     output wire Y | 
 | ); | 
 |  | 
 |     parameter [1:0] INV_A = 2'b00; | 
 |  | 
 | endmodule | 
 |  | 
 |  | 
 | module top( | 
 |     input  wire [3:0] di, | 
 |     output wire       do | 
 | ); | 
 |  | 
 |     wire [3:0] d; | 
 |  | 
 |     \$_NOT_ n0 (.A(di[0]), .Y(d[0])); | 
 |     \$_NOT_ n1 (.A(di[1]), .Y(d[1])); | 
 |     \$_NOT_ n2 (.A(di[2]), .Y(d[2])); | 
 |     \$_NOT_ n3 (.A(di[3]), .Y(d[3])); | 
 |  | 
 |     box #(.INV_A(2'b01)) the_box ( | 
 |         .A ({d[1], d[0]}), | 
 |         .B ({d[3], d[2]}), | 
 |  | 
 |         .Y (do) | 
 |     ); | 
 |  | 
 | endmodule |