add skidbuffer. Untested

tests/common/skidbuffer.sv

@@ -0,0 +1,55 @@
+module skidbuffer #(
+    parameter WIDTH = 1
+)(
+    input logic clk,
+    input logic reset,
+
+    input logic [WIDTH-1:0] in,
+    input logic in_valid,
+    output logic in_ready,
+
+    output logic [WIDTH-1:0] out,
+    output logic out_valid,
+    input logic out_ready
+);
+
+logic buffer_filled = 0;
+logic [WIDTH-1:0] buffer_val;
+
+always_ff @(posedge clk) begin
+    if (reset) begin
+        buffer_filled <= 0;
+    end else begin
+        if (in_valid && in_ready) begin
+            // input always gets stored whether it needs to be or not
+            buffer_val <= in;
+        end
+
+        if (buffer_filled) begin
+            if (out_ready && !(in_valid && in_ready)) begin
+                // out_valid = 1 since buffer is full
+                buffer_filled <= 0;
+            end
+        end else begin
+            if (in_valid && !(out_valid && out_ready)) begin
+                // in_ready = 1 since buffer is empty
+                buffer_val = in;
+                buffer_filled <= 1;
+            end
+        end
+    end
+end
+
+always_comb begin
+    if (buffer_filled) begin
+        in_ready = out_ready;
+        out_valid = 1;
+        out = buffer_val;
+    end else begin
+        in_ready = 1;
+        out_valid = in_valid;
+        out = in;
+    end
+end
+
+endmodule