Added examples/smtbmc/demo2.v

1 files changed, 29 insertions, 0 deletions

diff --git a/examples/smtbmc/demo2.v b/examples/smtbmc/demo2.v
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+++ b/examples/smtbmc/demo2.v
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+// Nothing to prove in this demo.
+// Just an example for memories, vcd dumps and vlog testbench dumps.
+
+`ifdef FORMAL
+`define assume(_expr_) assume(_expr_)
+`else
+`define assume(_expr_)
+`endif
+
+module demo2(input clk, input [4:0] addr, output reg [31:0] data);
+	reg [31:0] mem [0:31];
+	always @(posedge clk)
+		data <= mem[addr];
+
+	reg [31:0] used_addr = 0;
+	reg [31:0] used_dbits = 0;
+	reg initstate = 1;
+
+	always @(posedge clk) begin
+		initstate <= 0;
+		`assume(!used_addr[addr]);
+		used_addr[addr] <= 1;
+		if (!initstate) begin
+			`assume(data != 0);
+			`assume((used_dbits & data) == 0);
+			used_dbits <= used_dbits | data;
+		end
+	end
+endmodule