verilator/test_regress/t/t_assign_dff.v

92 lines
1.7 KiB
Systemverilog

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain.
// SPDX-FileCopyrightText: 2026 Antmicro
// SPDX-License-Identifier: CC0-1.0
// verilog_format: off
`define stop $stop
`define checkh(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d: got='h%x exp='h%x\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0);
// verilog_format: on
module t (
input clk
);
int cyc;
wire q;
logic d = 0, clear, preset;
dff flipflop (
q,
d,
clear,
preset,
clk
);
//clear and preset signals are in inverted logic
always @(posedge clk) begin
cyc <= cyc + 1;
if (cyc == 0) begin
clear = 1;
preset = 0;
d = 0;
end
else if (cyc == 1) begin
`checkh(q, 1);
preset = 1;
d = 1;
end
else if (cyc == 2) begin
`checkh(q, 1);
clear = 0;
end
else if (cyc == 3) begin
`checkh(q, 0);
preset = 0;
end
else if (cyc == 4) begin
`checkh(q, 0);
clear = 1;
preset = 1;
end
else if (cyc == 5) begin
`checkh(q, 1);
d = 0;
end
else if (cyc == 6) begin
`checkh(q, 0);
d = 1;
end
else if (cyc == 7) begin
`checkh(q, 1);
end
else if (cyc == 8) begin
$write("*-* All Finished *-*\n");
$finish;
end
end
endmodule
// From IEEE 1800-2023 10.6.1
module dff (
q,
d,
clear,
preset,
clock
);
output q;
input d, clear, preset, clock;
logic q;
always @(clear or preset)
if (!clear) assign q = 0;
else if (!preset) assign q = 1;
else deassign q;
always @(posedge clock) q = d;
endmodule