Add meminit handling for NX_RFB_U

tests/arch/nanoxplore/meminit.v

@@ -0,0 +1,50 @@
+module top(clk);
+parameter DEPTH_LOG2 = 10;
+parameter WIDTH = 36;
+parameter PRIME = 237481091;
+localparam DEPTH = 2**DEPTH_LOG2;
+
+input wire clk;
+
+(* syn_ramstyle = "distributed" *)
+reg [WIDTH-1:0] mem [DEPTH-1:0];
+
+integer i;
+initial begin
+    for (i = 0; i < DEPTH; i = i + 1) begin
+        // Make up data by multiplying a large prime with the address,
+        // then cropping and retaining the lower bits
+        mem[i] = PRIME * (i*2+1);
+    end
+end
+
+reg [DEPTH_LOG2-1:0] counter = 0;
+reg done = 1'b0;
+
+reg did_read = 1'b0;
+reg [DEPTH_LOG2-1:0] read_addr;
+reg [WIDTH-1:0] read_val;
+
+always @(posedge clk) begin
+    if (!done) begin
+        did_read <= 1'b1;
+        read_addr <= counter;
+        read_val <= mem[counter];
+    end else begin
+        did_read <= 1'b0; 
+    end
+
+    if (!done)
+        counter = counter + 1;
+    if (counter == 0)
+        done = 1;
+end
+
+wire [WIDTH-1:0] expect_val = PRIME * (read_addr*2+1);
+always @(posedge clk) begin
+    if (did_read) begin
+        $display("addr %x expected %x actual %x", read_addr, expect_val, read_val);
+        assert(read_val == expect_val);
+    end
+end
+endmodule