|  | // 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 |