Added scripts/cxxdemo/

1 files changed, 95 insertions, 0 deletions

diff --git a/scripts/cxxdemo/testbench.v b/scripts/cxxdemo/testbench.v
new file mode 100644
index 0000000..b8bed17
--- /dev/null
+++ b/scripts/cxxdemo/testbench.v
@@ -0,0 +1,95 @@
+`timescale 1 ns / 1 ps
+`undef VERBOSE_MEM
+`undef WRITE_VCD
+
+module testbench;
+	reg clk = 1;
+	reg resetn = 0;
+	wire trap;
+
+	always #5 clk = ~clk;
+
+	initial begin
+		repeat (100) @(posedge clk);
+		resetn <= 1;
+	end
+
+	wire mem_valid;
+	wire mem_instr;
+	reg mem_ready;
+	wire [31:0] mem_addr;
+	wire [31:0] mem_wdata;
+	wire [3:0] mem_wstrb;
+	reg  [31:0] mem_rdata;
+
+	picorv32 uut (
+		.clk         (clk        ),
+		.resetn      (resetn     ),
+		.trap        (trap       ),
+		.mem_valid   (mem_valid  ),
+		.mem_instr   (mem_instr  ),
+		.mem_ready   (mem_ready  ),
+		.mem_addr    (mem_addr   ),
+		.mem_wdata   (mem_wdata  ),
+		.mem_wstrb   (mem_wstrb  ),
+		.mem_rdata   (mem_rdata  )
+	);
+
+	localparam MEM_SIZE = 4*1024*1024;
+	reg [7:0] memory [0:MEM_SIZE-1];
+	initial $readmemh("firmware.hex", memory);
+
+	always @(posedge clk) begin
+		mem_ready <= 0;
+		if (mem_valid && !mem_ready) begin
+			mem_ready <= 1;
+			mem_rdata <= 'bx;
+			case (1)
+				mem_addr < MEM_SIZE: begin
+					if (|mem_wstrb) begin
+						if (mem_wstrb[0]) memory[mem_addr + 0] <= mem_wdata[ 7: 0];
+						if (mem_wstrb[1]) memory[mem_addr + 1] <= mem_wdata[15: 8];
+						if (mem_wstrb[2]) memory[mem_addr + 2] <= mem_wdata[23:16];
+						if (mem_wstrb[3]) memory[mem_addr + 3] <= mem_wdata[31:24];
+					end else begin
+						mem_rdata <= {memory[mem_addr+3], memory[mem_addr+2], memory[mem_addr+1], memory[mem_addr]};
+					end
+				end
+				mem_addr == 32'h 1000_0000: begin
+					$write("%c", mem_wdata[7:0]);
+				end
+			endcase
+		end
+		if (mem_valid && mem_ready) begin
+`ifdef VERBOSE_MEM
+			if (|mem_wstrb)
+				$display("WR: ADDR=%x DATA=%x MASK=%b", mem_addr, mem_wdata, mem_wstrb);
+			else
+				$display("RD: ADDR=%x DATA=%x%s", mem_addr, mem_rdata, mem_instr ? " INSN" : "");
+`endif
+			if (^mem_addr === 1'bx ||
+					(mem_wstrb[0] && ^mem_wdata[ 7: 0] == 1'bx) ||
+					(mem_wstrb[1] && ^mem_wdata[15: 8] == 1'bx) ||
+					(mem_wstrb[2] && ^mem_wdata[23:16] == 1'bx) ||
+					(mem_wstrb[3] && ^mem_wdata[31:24] == 1'bx)) begin
+				$display("CRITICAL UNDEF MEM TRANSACTION");
+				$finish;
+			end
+		end
+	end
+
+`ifdef WRITE_VCD
+	initial begin
+		$dumpfile("testbench.vcd");
+		$dumpvars(0, testbench);
+	end
+`endif
+
+	always @(posedge clk) begin
+		if (resetn && trap) begin
+			repeat (10) @(posedge clk);
+			$display("TRAP");
+			$finish;
+		end
+	end
+endmodule