| module top | |
| ( | |
| input x, | |
| input y, | |
| input cin, | |
| output reg A, | |
| output reg cout | |
| ); | |
| wire bb_out; | |
| initial begin | |
| A = 0; | |
| cout = 0; | |
| end | |
| `ifndef BUG | |
| always @(posedge x) begin | |
| A <= y + cin; | |
| end | |
| always @(negedge x) begin | |
| cout <= y + A; | |
| end | |
| `else | |
| assign {cout,A} = cin - y * x; | |
| `endif | |
| bb ubb (cin,y,x,bb_out); | |
| endmodule | |
| (* black_box *) module bb(in1, in2, clk, out1); | |
| input in1; | |
| input in2; | |
| input clk; | |
| output reg out1; | |
| always @(posedge clk) | |
| out1 <= in1 & in2; | |
| endmodule |