Add counter.sv SVA test

diff --git a/tests/sva/counter.sv b/tests/sva/counter.sv
new file mode 100644 (file)
index 0000000..5e4b77e
--- /dev/null
+++ b/tests/sva/counter.sv
@@ -0,0 +1,29 @@
+module top (input clk, reset, up, down, output reg [7:0] cnt);
+       always @(posedge clk) begin
+               if (reset)
+                       cnt <= 0;
+               else if (up)
+                       cnt <= cnt + 1;
+               else if (down)
+                       cnt <= cnt - 1;
+       end
+
+       default clocking @(posedge clk); endclocking
+       default disable iff (reset);
+
+       assert property (up |=> cnt == $past(cnt) + 8'd1);
+       // assert property (up [*2] |=> cnt == $past(cnt, 2) + 8'd2);
+       // assert property (up ##1 up |=> cnt == $past(cnt, 2) + 8'd2);
+
+`ifndef FAIL
+       assume property (down |-> !up);
+`endif
+       assert property (down |=> cnt == $past(cnt) - 8'd1);
+
+       property down_n(n);
+               down [*n] |=> cnt == $past(cnt, n) + n;
+       endproperty
+
+       // assert property (down_n(3));
+       // assert property (down_n(5));
+endmodule