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// DESCRIPTION: Verilator: Verilog Test module
// This file ONLY is placed under the Creative Commons Public Domain, for
// any use, without warranty, 2020 by Wilson Snyder.
// SPDX-License-Identifier: CC0-1.0
// verilator lint_off WIDTH
// verilator lint_off VARHIDDEN
module t (
clk
);
input clk;
integer cyc = 0;
reg [63:0] crc; initial crc = 64'h1;
chk chk (.clk (clk),
.rst_l (1'b1),
.expr (|crc)
);
always @ (posedge clk) begin
cyc <= cyc + 1;
crc <= {crc[62:0], crc[63] ^ crc[2] ^ crc[0]};
if (cyc==0) begin
crc <= 64'h5aef0c8d_d70a4497;
end
else if (cyc<90) begin
end
else if (cyc==99) begin
$write("*-* All Finished *-*\n");
$finish;
end
end
endmodule
module chk (input clk, input rst_l, input expr);
integer errors; initial errors = 0;
task printerr;
input [8*64:1] msg;
begin
errors = errors + 1;
$write("%%Error: %0s\n", msg);
$stop;
end
endtask
always @(posedge clk) begin
if (rst_l) begin
if (expr == 1'b0) begin
printerr("expr not asserted");
end
end
end
wire noxs = ((expr ^ expr) == 1'b0);
// TODO: this test is dodgy, noxs can be proven constant, so this block
// should never relly trigger...
reg hasx;
always @ (noxs) begin
if (noxs) begin
hasx = 1'b0;
end
else begin
hasx = 1'b1;
end
end
always @(posedge clk) begin
if (rst_l) begin
if (hasx) begin
printerr("expr has unknowns");
end
end
end
endmodule
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