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`timescale 1us/1us
module counter_tb;
logic tst_clk, tst_store_X, tst_count;
logic [15:0] tst_in_X, tst_result;
counter uut (
.clk_in(tst_clk),
.X_in(tst_in_X),
.counter_out(tst_result),
.st_store_X_in(tst_store_X),
.count_enable_in(tst_count)
);
string filename;
initial begin
`ifdef DUMP_FILE_NAME
filename=`DUMP_FILE_NAME;
`else
filename="counter.lxt2";
`endif
$dumpfile(filename); $dumpvars();
tst_clk = 0;
tst_store_X = 0;
tst_in_X = 0;
tst_count = 0;
end
always #10 tst_clk = ~tst_clk;
initial begin
// start of with count disabled
repeat(5) @(posedge tst_clk);
assert (tst_result == 0)
else $error("Expected 0, got %d", tst_result);
tst_count = 1;
// now that counting is enabled
repeat(5) @(posedge tst_clk);
assert (tst_result == 5)
else $error("Expected 5, got %d", tst_result);
@(posedge tst_clk);
tst_store_X = 1;
tst_in_X = 16'd834;
repeat(3) begin
@(posedge tst_clk);
assert (tst_result == 834)
else $error("Expected 834, got %d", tst_result);
// this shouldn't matter
tst_count = !tst_count;
end
tst_store_X = 0;
tst_count = 1;
@(posedge tst_clk);
assert (tst_result == 835)
else $error("Expected 835, got %d", tst_result);
#30
$finish();
end
endmodule
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