RTOS bug fixing and update example to use Signal

Author: tact1m4n3

examples/espressif/esp/src/tcp_server.zig

@@ -52,7 +52,7 @@ const SERVER_PORT = 3333;
 
 var maybe_netif: ?*lwip.c.netif = null;
 
-var ip_ready_semaphore: rtos.Semaphore = .init(0, 1);
+var ip_ready_signal: rtos.Signal(void) = .{};
 var ip: lwip.c.ip_addr_t = undefined;
 
 extern fn netconn_new_with_proto_and_callback(t: lwip.c.enum_netconn_type, proto: lwip.c.u8_t, callback: ?*const anyopaque) [*c]lwip.c.struct_netconn;
@@ -103,9 +103,10 @@ pub fn main() !void {
     }
 
     try radio.wifi.connect_blocking();
+
     try lwip.c_err(lwip.c.netifapi_netif_common(&netif, lwip.c.netif_set_link_up, null));
 
-    ip_ready_semaphore.take();
+    ip_ready_signal.wait();
     std.log.info("Listening on {f}:{}", .{ IP_Formatter.init(netif.ip_addr), SERVER_PORT });
 
     const server_conn = netconn_new_with_proto_and_callback(lwip.c.NETCONN_TCP, 0, null) orelse {
@@ -201,7 +202,7 @@ fn netif_status_callback(netif_ptr: [*c]lwip.c.netif) callconv(.c) void {
     const netif = &netif_ptr[0];
     if (netif.ip_addr.u_addr.ip4.addr != 0) {
         ip = netif.ip_addr;
-        ip_ready_semaphore.give();
+        ip_ready_signal.put({});
     }
 }