1 files changed, 30 insertions, 0 deletions
diff --git a/rtl/src/io.v b/rtl/src/io.v
new file mode 100644
index 0000000..f53062b
--- /dev/null
+++ b/rtl/src/io.v
@@ -0,0 +1,30 @@
+module io (
+  input clk,
+  input rstn,
+
+  input we,
+  input [31:0] addr,
+  input [31:0] wd,
+
+  output reg [31:0] rd,
+
+  input [31:0] io_in,
+  output reg [31:0] io_out
+);
+
+`include "include/consts.vh"
+
+always @ (posedge clk or negedge rstn) begin
+  if (!rstn) begin
+    io_out <= 32'b0;
+  end else if (we && addr == 32'h0000_0004) begin
+    io_out <= wd;
+  end
+end
+
+always @ (posedge clk) begin
+  if      (addr == 32'h0000_0000) rd <= io_in;
+  else if (addr == 32'h0000_0004) rd <= io_out;
+  else                            rd <= 32'b0;
+end
+endmodule
+\ No newline at end of file