|  | // 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 A, | 
|  | output wire Y | 
|  | ); | 
|  |  | 
|  | parameter [0:0] INV_A = 1'b0; | 
|  |  | 
|  | endmodule | 
|  |  | 
|  | (* keep_hierarchy *) | 
|  | module child ( | 
|  | input  wire       I, | 
|  | output wire [1:0] O | 
|  | ); | 
|  |  | 
|  | wire d; | 
|  |  | 
|  | \$_NOT_ n (.A(I), .Y(d)); | 
|  |  | 
|  | box b0 (.A(I), .Y(O[0])); | 
|  | box b1 (.A(d), .Y(O[1])); | 
|  |  | 
|  | endmodule | 
|  |  | 
|  |  | 
|  | module top( | 
|  | input  wire       di, | 
|  | output wire [4:0] do | 
|  | ); | 
|  |  | 
|  | wire [1:0] d; | 
|  |  | 
|  | \$_NOT_ n0 (.A(di), .Y(d[0])); | 
|  | \$_NOT_ n1 (.A(di), .Y(d[1])); | 
|  |  | 
|  | box   b0 (.A(d[0]), .Y(do[0])); | 
|  | box   b1 (.A(d[1]), .Y(do[1])); | 
|  | child c  (.I(d[1]), .O({do[3], do[2]})); | 
|  |  | 
|  | endmodule |