1 files changed, 105 insertions, 0 deletions
diff --git a/techlibs/ice40/tests/test_bram_tb.v b/techlibs/ice40/tests/test_bram_tb.v
new file mode 100644
index 00000000..b0ac0402
--- /dev/null
+++ b/techlibs/ice40/tests/test_bram_tb.v
@@ -0,0 +1,105 @@
+module bram_tb #(
+	parameter ABITS = 8, DBITS = 8
+);
+	reg clk;
+	reg [ABITS-1:0] WR_ADDR;
+	reg [DBITS-1:0] WR_DATA;
+	reg WR_EN;
+	reg [ABITS-1:0] RD_ADDR;
+	wire [DBITS-1:0] RD_DATA;
+
+	bram uut  (
+		.clk    (clk    ),
+		.WR_ADDR(WR_ADDR),
+		.WR_DATA(WR_DATA),
+		.WR_EN  (WR_EN  ),
+		.RD_ADDR(RD_ADDR),
+		.RD_DATA(RD_DATA)
+	);
+
+	reg [63:0] xorshift64_state = 64'd88172645463325252 ^ (ABITS << 24) ^ (DBITS << 16);
+
+	task xorshift64_next;
+		begin
+		// see page 4 of Marsaglia, George (July 2003). "Xorshift RNGs". Journal of Statistical Software 8 (14).
+		xorshift64_state = xorshift64_state ^ (xorshift64_state << 13);
+		xorshift64_state = xorshift64_state ^ (xorshift64_state >>  7);
+		xorshift64_state = xorshift64_state ^ (xorshift64_state << 17);
+		end
+	endtask
+
+	reg [ABITS-1:0] randaddr1;
+	reg [ABITS-1:0] randaddr2;
+	reg [ABITS-1:0] randaddr3;
+
+	function [31:0] getaddr(input [3:0] n);
+		begin
+			case (n)
+				0: getaddr = 0;
+				1: getaddr = 2**ABITS-1;
+				2: getaddr = 'b101 << (ABITS / 3);
+				3: getaddr = 'b101 << (2*ABITS / 3);
+				4: getaddr = 'b11011 << (ABITS / 4);
+				5: getaddr = 'b11011 << (2*ABITS / 4);
+				6: getaddr = 'b11011 << (3*ABITS / 4);
+				7: getaddr = randaddr1;
+				8: getaddr = randaddr2;
+				9: getaddr = randaddr3;
+				default: begin
+					getaddr = 1 << (2*n-16);
+					if (!getaddr) getaddr = xorshift64_state;
+				end
+			endcase
+		end
+	endfunction
+
+	reg [DBITS-1:0] memory [0:2**ABITS-1];
+	reg [DBITS-1:0] expected_rd, expected_rd_masked;
+
+	event error;
+	integer i, j;
+
+	initial begin
+		// $dumpfile("testbench.vcd");
+		// $dumpvars(0, bram_tb);
+
+		xorshift64_next;
+		xorshift64_next;
+		xorshift64_next;
+		xorshift64_next;
+
+		randaddr1 = xorshift64_state;
+		xorshift64_next;
+
+		randaddr2 = xorshift64_state;
+		xorshift64_next;
+
+		randaddr3 = xorshift64_state;
+		xorshift64_next;
+
+		clk <= 0;
+		for (i = 0; i < 512; i = i+1) begin
+			WR_DATA <= xorshift64_state;
+			xorshift64_next;
+
+			WR_ADDR <= getaddr(i < 256 ? i[7:4] : xorshift64_state[63:60]);
+			xorshift64_next;
+
+			RD_ADDR <= getaddr(i < 256 ? i[3:0] : xorshift64_state[59:56]);
+			WR_EN <= xorshift64_state[55];
+			xorshift64_next;
+
+			#1; clk <= 1;
+			#1; clk <= 0;
+
+			expected_rd = memory[RD_ADDR];
+			if (WR_EN) memory[WR_ADDR] = WR_DATA;
+
+			for (j = 0; j < DBITS; j = j+1)
+				expected_rd_masked[j] = expected_rd[j] !== 1'bx ? expected_rd[j] : RD_DATA[j];
+
+			$display("#OUT# %3d | WA=%x WD=%x WE=%x | RA=%x RD=%x (%x) | %s", i, WR_ADDR, WR_DATA, WR_EN, RD_ADDR, RD_DATA, expected_rd, expected_rd_masked === RD_DATA ? "ok" : "ERROR");
+			if (expected_rd_masked !== RD_DATA) begin -> error; end
+		end
+	end
+endmodule