```
// ===========================================================
// SyncClearFlipFlop: ?Shows a flip-flop with synchronous
// clear.
//
// ------------------------------------------------------------
// 2005-02-14 jmw: v. 1.2 Added separate testbench module.
// 2005-01-27 jmw: v. 1.1 Changed some nonblocking delays for
// ? ? ? ? ? ?synthesis.
// 2004-12-03 jmw: v. 1.0 implemented.
// ============================================================
//
`timescale 1ns/100ps
//
module SyncClearFlipFlop (output Q, input D, clk, clr);
//
reg QReg;// Storage.
//
// ========= End declarations. =====================
//
assign #1 Q = QReg; // Put stored value on I/O.
//
// ----------------------------------
// Just remove the clr sensitivity:
//
always@(posedge clk)
begin
if (clr == 1'b1)
QReg <= 1'b0;
else QReg <= D;
end
//
endmodule // SyncClearFlipFlop.
// ========= End behavior. =========================
//
? `ifdef DC
? `else
module SyncClearTst;
//
wire QWire;
reg clk, D, clr;
//
always@(clk) #5 clk <= ~clk;
//
initial
begin
//
#0 D = 1'b0;
clr = 1'b0;
#02 clk = 1'b0; // Start clock shift vs other changes.
//
#03 D = 1'b1;
#05 D = 1'b0;
#10 clr = 1'b1;
#10 clr = 1'b0;
#05 D = 1'b1;
#10 clr = 1'b1;
#10 clr = 1'b0;
//
#15 $finish;
end
SyncClearFlipFlop SC\_FF1 ( .Q(QWire), .D(D), .clk(clk), .clr(clr) );
//
endmodule // SyncClearTst.
? `endif
```
