feat: add Modbus support

lib/eModbus/src/ModbusServerTCPasync.h

@@ -0,0 +1,92 @@
+// =================================================================================================
+// eModbus: Copyright 2020 by Michael Harwerth, Bert Melis and the contributors to eModbus
+//               MIT license - see license.md for details
+// =================================================================================================
+#ifndef _MODBUS_SERVER_TCP_ASYNC_H
+#define _MODBUS_SERVER_TCP_ASYNC_H
+
+#include "options.h"
+
+#include <list>
+#include <queue>
+#if USE_MUTEX
+#include <mutex> // NOLINT
+#endif
+#include <vector>
+
+#include <Arduino.h> // for millis()
+
+#if defined(ESP32)
+#include <AsyncTCP.h>
+#elif defined(ESP8266)
+#include <ESPAsyncTCP.h>
+#endif
+
+#include "ModbusServer.h"
+
+#if USE_MUTEX
+using std::lock_guard;
+#endif
+
+class ModbusServerTCPasync : public ModbusServer {
+  private:
+    class mb_client {
+        friend class ModbusServerTCPasync;
+
+      public:
+        mb_client(ModbusServerTCPasync * s, AsyncClient * c);
+        ~mb_client();
+
+      private:
+        void                        onData(uint8_t * data, size_t len);
+        void                        onPoll();
+        void                        onDisconnect();
+        void                        addResponseToOutbox(ModbusMessage * response);
+        void                        handleOutbox();
+        ModbusServerTCPasync *      server;
+        AsyncClient *               client;
+        uint32_t                    lastActiveTime;
+        ModbusMessage *             message;
+        Modbus::Error               error;
+        std::queue<ModbusMessage *> outbox;
+#if USE_MUTEX
+        std::mutex obLock; // outbox protection
+#endif
+    };
+
+
+  public:
+    // Constructor
+    ModbusServerTCPasync();
+
+    // Destructor: closes the connections
+    ~ModbusServerTCPasync();
+
+    // activeClients: return number of clients currently employed
+    uint16_t activeClients();
+
+    // start: create task with TCP server to accept requests
+    bool start(uint16_t port, uint8_t max_clients, uint32_t timeout, int coreID = -1);
+
+    // stop: drop all connections and kill server task
+    bool stop();
+
+    // isRunning: return true is server is running
+    bool isRunning();
+
+  protected:
+    inline void isInstance() {
+    }
+    void onClientConnect(AsyncClient * client);
+    void onClientDisconnect(mb_client * client);
+
+    AsyncServer *          server;
+    std::list<mb_client *> clients;
+    uint8_t                maxNoClients;
+    uint32_t               idle_timeout;
+#if USE_MUTEX
+    std::mutex cListLock; // client list protection
+#endif
+};
+
+#endif