sync: Add signal synchronizer module

Signed-off-by: Alex Forencich <alex@alexforencich.com>

rtl/sync/taxi_sync_signal.sv

@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: CERN-OHL-S-2.0
+/*
+
+Copyright (c) 2014-2025 FPGA Ninja, LLC
+
+Authors:
+- Alex Forencich
+
+*/
+
+`resetall
+`timescale 1ns / 1ps
+`default_nettype none
+
+/*
+ * Synchronizes an asynchronous signal to a given clock by using a pipeline of
+ * two registers.
+ */
+module taxi_sync_signal #(
+    // width of the input and output signals
+    parameter WIDTH = 1,
+    // depth of synchronizer
+    parameter N = 2
+)
+(
+    input  wire logic              clk,
+
+    input  wire logic [WIDTH-1:0]  in,
+    output wire logic [WIDTH-1:0]  out
+);
+
+(* srl_style = "register" *)
+logic [WIDTH-1:0] sync_reg[N-1:0];
+
+assign out = sync_reg[N-1];
+
+always_ff @(posedge clk) begin
+    sync_reg[0] <= in;
+    for (integer k = 1; k < N; k = k + 1) begin
+        sync_reg[k] <= sync_reg[k-1];
+    end
+end
+
+endmodule
+
+`resetall