feat: add Modbus support

lib/eModbus/src/ModbusServer.h

@@ -0,0 +1,86 @@
+// =================================================================================================
+// eModbus: Copyright 2020 by Michael Harwerth, Bert Melis and the contributors to eModbus
+//               MIT license - see license.md for details
+// =================================================================================================
+#ifndef _MODBUS_SERVER_H
+#define _MODBUS_SERVER_H
+
+#include "options.h"
+
+#include <map>
+#include <vector>
+#include <functional>
+#if USE_MUTEX
+#include <mutex>      // NOLINT
+#endif
+#include "ModbusTypeDefs.h"
+#include "ModbusError.h"
+#include "ModbusMessage.h"
+
+#if USE_MUTEX
+using std::mutex;
+using std::lock_guard;
+#endif
+
+// Standard response variants for "no response" and "echo the request"
+const ModbusMessage NIL_RESPONSE (std::vector<uint8_t>{0xFF, 0xF0});
+const ModbusMessage ECHO_RESPONSE(std::vector<uint8_t>{0xFF, 0xF1});
+
+// MBSworker: function signature for worker functions to handle single serverID/functionCode combinations
+using MBSworker = std::function<ModbusMessage(ModbusMessage msg)>;
+
+class ModbusServer {
+public:
+  // registerWorker: register a worker function for a certain serverID/FC combination
+  // If there is one already, it will be overwritten!
+  void registerWorker(uint8_t serverID, uint8_t functionCode, MBSworker worker);
+  
+  // getWorker: if a worker function is registered, return its address, nullptr otherwise
+  MBSworker getWorker(uint8_t serverID, uint8_t functionCode);
+
+  // unregisterWorker; remove again all or part of the registered workers for a given server ID
+  // Returns true if the worker was found and removed
+  bool unregisterWorker(uint8_t serverID, uint8_t functionCode = 0);
+
+  // isServerFor: if any worker function is registered for the given serverID, return true
+  bool isServerFor(uint8_t serverID);
+
+  // getMessageCount: read number of messages processed
+  uint32_t getMessageCount();
+
+  // getErrorCount: read number of errors responded
+  uint32_t getErrorCount();
+
+  // resetCounts: set both message and error counts to zero
+  void resetCounts();
+
+  // Local request to the server
+  ModbusMessage localRequest(ModbusMessage msg);
+
+  // listServer: print out all server/FC combinations served
+  void listServer();
+
+protected:
+  // Constructor
+  ModbusServer();
+
+  // Destructor
+  ~ModbusServer();
+
+  // Prevent copy construction or assignment
+  ModbusServer(ModbusServer& other) = delete;
+  ModbusServer& operator=(ModbusServer& other) = delete;
+
+  // Virtual function to prevent this class being instantiated
+  virtual void isInstance() = 0;
+
+  std::map<uint8_t, std::map<uint8_t, MBSworker>> workerMap;      // map on serverID->functionCode->worker function
+  uint32_t messageCount;         // Number of Requests processed
+  uint32_t errorCount;           // Number of errors responded
+  #if USE_MUTEX
+  mutex m;                       // mutex to cover changes to messageCount and errorCount
+  #endif
+};
+
+
+#endif