feat: add Modbus support

lib/eModbus/src/ModbusClient.h

@@ -0,0 +1,119 @@
+// =================================================================================================
+// eModbus: Copyright 2020 by Michael Harwerth, Bert Melis and the contributors to eModbus
+//               MIT license - see license.md for details
+// =================================================================================================
+#ifndef _MODBUS_CLIENT_H
+#define _MODBUS_CLIENT_H
+
+#include <functional> 
+#include <map>
+#include "options.h"
+#include "ModbusMessage.h"
+
+#if HAS_FREERTOS
+extern "C" {
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
+}
+#elif IS_LINUX
+#include <pthread.h>
+#endif
+
+#if USE_MUTEX
+#include <mutex>                    // NOLINT
+using std::mutex;
+using std::lock_guard;
+#endif
+
+typedef std::function<void(ModbusMessage msg, uint32_t token)> MBOnData;
+typedef std::function<void(Modbus::Error errorCode, uint32_t token)> MBOnError;
+typedef std::function<void(ModbusMessage msg, uint32_t token)> MBOnResponse;
+
+class ModbusClient {
+public:
+  bool onDataHandler(MBOnData handler);   // Accept onData handler 
+  bool onErrorHandler(MBOnError handler); // Accept onError handler 
+  bool onResponseHandler(MBOnResponse handler); // Accept onResponse handler 
+  uint32_t getMessageCount();             // Informative: return number of messages created
+  uint32_t getErrorCount();              // Informative: return number of errors received
+  void resetCounts();                    // Set both message and error counts to zero
+  inline Error addRequest(ModbusMessage m, uint32_t token) { return addRequestM(m, token); }
+  inline ModbusMessage syncRequest(ModbusMessage m, uint32_t token) { return syncRequestM(m, token); }
+
+  // Template function to generate syncRequest functions as long as there is a 
+  // matching ModbusMessage::setMessage() call
+  template <typename... Args>
+  ModbusMessage syncRequest(uint32_t token, Args&&... args) {
+    Error rc = SUCCESS;
+    // Create request, if valid
+    ModbusMessage m;
+    rc = m.setMessage(std::forward<Args>(args) ...);
+
+    // Add it to the queue and wait for a response, if valid
+    if (rc == SUCCESS) {
+      return syncRequestM(m, token);
+    } 
+    // Else return the error as a message
+    return buildErrorMsg(rc, std::forward<Args>(args) ...);
+  }
+
+  // Template function to create an error response message from a variadic pattern
+  template <typename... Args>
+  ModbusMessage buildErrorMsg(Error e, uint8_t serverID, uint8_t functionCode, Args&&... args) {
+    ModbusMessage m;
+    m.setError(serverID, functionCode, e);
+    return m;
+  }
+
+  // Template function to generate addRequest functions as long as there is a 
+  // matching ModbusMessage::setMessage() call
+  template <typename... Args>
+  Error addRequest(uint32_t token, Args&&... args) {
+    Error rc = SUCCESS;        // Return value
+
+    // Create request, if valid
+    ModbusMessage m;
+    rc = m.setMessage(std::forward<Args>(args) ...);
+
+    // Add it to the queue, if valid
+    if (rc == SUCCESS) {
+      return addRequestM(m, token);
+    }
+    // Else return the error
+    return rc;
+  }
+
+protected:
+  ModbusClient();             // Default constructor
+  virtual void isInstance() = 0;   // Make class abstract
+  ModbusMessage waitSync(uint8_t serverID, uint8_t functionCode, uint32_t token); // wait for syncRequest response to arrive
+  // Virtual addRequest variant needed internally. All others done by template!
+  virtual Error addRequestM(ModbusMessage msg, uint32_t token) = 0;
+  // Virtual syncRequest variant following the same pattern
+  virtual ModbusMessage syncRequestM(ModbusMessage msg, uint32_t token) = 0;
+  // Prevent copy construction or assignment
+  ModbusClient(ModbusClient& other) = delete;
+  ModbusClient& operator=(ModbusClient& other) = delete;
+
+  uint32_t messageCount;           // Number of requests generated. Used for transactionID in TCPhead
+  uint32_t errorCount;             // Number of errors received
+#if HAS_FREERTOS
+  TaskHandle_t worker;             // Interface instance worker task
+#elif IS_LINUX
+  pthread_t worker;
+#endif
+  MBOnData onData;                 // Data response handler
+  MBOnError onError;               // Error response handler
+  MBOnResponse onResponse;         // Uniform response handler
+  static uint16_t instanceCounter; // Number of ModbusClients created
+  std::map<uint32_t, ModbusMessage> syncResponse; // Map to hold response messages on synchronous requests
+#if USE_MUTEX
+  std::mutex syncRespM;            // Mutex protecting syncResponse map against race conditions
+  std::mutex countAccessM;         // Mutex protecting access to the message and error counts
+#endif
+
+  // Let any ModbusBridge class use protected members
+  template<typename SERVERCLASS> friend class ModbusBridge;
+};
+
+#endif