comm_drv_n2k_serial.cpp

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/***************************************************************************
 *   Copyright (C) 2022 by David Register                                  *
 *   Copyright (C) 2022 Alec Leamas                                        *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, see <https://www.gnu.org/licenses/>. *
 **************************************************************************/
 
#include <mutex>  // std::mutex
#include <queue>  // std::queue
#include <vector>
 
// For compilers that support precompilation, includes "wx.h".
#include <wx/wxprec.h>
#ifndef WX_PRECOMP
#include <wx/wx.h>
#endif
 
#include <wx/log.h>
 
#include "model/comm_buffers.h"
#include "model/comm_drv_n2k_serial.h"
#include "model/comm_navmsg_bus.h"
#include "model/comm_drv_registry.h"
#include "model/logger.h"
#include "model/comm_drv_stats.h"
 
#include "N2kMsg.h"
 
/* Copied from canboat Project
 * https://github.com/canboat/canboat
 *
 * The following startup command reverse engineered from Actisense NMEAreader.
 * It instructs the NGT1 to clear its PGN message TX list, thus it starts
 * sending all PGNs that it knows about.
 */
static unsigned char NGT_STARTUP_SEQ[] = {
    0x11, /* msg byte 1, meaning ? */
    0x02, /* msg byte 2, meaning ? */
    0x00  /* msg byte 3, meaning ? */
};
 
static std::vector<unsigned char> BufferToActisenseFormat(tN2kMsg& msg);
 
class CommDriverN2KSerialEvent;  // fwd
 
class CommDriverN2KSerialThread : public wxThread {
public:
  CommDriverN2KSerialThread(CommDriverN2KSerial* Launcher,
                            const wxString& PortName,
                            const wxString& strBaudRate);
 
  ~CommDriverN2KSerialThread();
  void* Entry();
  bool SetOutMsg(const std::vector<unsigned char>& load);
  void OnExit();
  DriverStats GetStats() const;
 
private:
#ifndef __ANDROID__
  serial::Serial m_serial;
#endif
  void ThreadMessage(const wxString& msg);
  bool OpenComPortPhysical(const wxString& com_name, int baud_rate);
  void CloseComPortPhysical();
  size_t WriteComPortPhysical(std::vector<unsigned char> msg);
  size_t WriteComPortPhysical(unsigned char* msg, size_t length);
  void SetGatewayOperationMode();
 
  CommDriverN2KSerial* m_pParentDriver;
  wxString m_PortName;
  wxString m_FullPortName;
 
  unsigned char* put_ptr;
  unsigned char* tak_ptr;
 
  unsigned char* rx_buffer;
 
  int m_baud;
  int m_n_timeout;
 
  CircularBuffer<std::vector<unsigned char>> m_out_que;
  DriverStats m_driver_stats;
  mutable std::mutex m_stats_mutex;
#ifdef __WXMSW__
  HANDLE m_hSerialComm;
  bool m_nl_found;
#endif
};
 
class CommDriverN2KSerialEvent;
wxDECLARE_EVENT(wxEVT_COMMDRIVER_N2K_SERIAL, CommDriverN2KSerialEvent);
 
class CommDriverN2KSerialEvent : public wxEvent {
public:
  CommDriverN2KSerialEvent(wxEventType commandType = wxEVT_NULL, int id = 0)
      : wxEvent(id, commandType) {};
  ~CommDriverN2KSerialEvent() {};
 
  // accessors
  void SetPayload(std::shared_ptr<std::vector<unsigned char>> data) {
    m_payload = data;
  }
  std::shared_ptr<std::vector<unsigned char>> GetPayload() { return m_payload; }
 
  // required for sending with wxPostEvent()
  wxEvent* Clone() const {
    CommDriverN2KSerialEvent* newevent = new CommDriverN2KSerialEvent(*this);
    newevent->m_payload = this->m_payload;
    return newevent;
  };
 
private:
  std::shared_ptr<std::vector<unsigned char>> m_payload;
};
 
//========================================================================
/*    commdriverN2KSerial implementation
 * */
 
wxDEFINE_EVENT(wxEVT_COMMDRIVER_N2K_SERIAL, CommDriverN2KSerialEvent);
 
CommDriverN2KSerial::CommDriverN2KSerial(const ConnectionParams* params,
                                         DriverListener& listener)
    : CommDriverN2K(params->GetStrippedDSPort()),
      m_Thread_run_flag(-1),
      m_params(*params),
      m_bok(false),
      m_portstring(params->GetDSPort()),
      m_pSecondary_Thread(NULL),
      m_listener(listener),
      m_stats_timer(*this, 2s),
      m_closing(false) {
  m_BaudRate = wxString::Format("%i", params->Baudrate), SetSecThreadInActive();
  m_manufacturers_code = 0;
  m_got_mfg_code = false;
  this->attributes["canAddress"] = std::string("-1");
  this->attributes["userComment"] = params->UserComment.ToStdString();
  this->attributes["ioDirection"] = DsPortTypeToString(params->IOSelect);
 
  // Prepare the wxEventHandler to accept events from the actual hardware thread
  Bind(wxEVT_COMMDRIVER_N2K_SERIAL, &CommDriverN2KSerial::handle_N2K_SERIAL_RAW,
       this);
 
  // Dummy Driver Stats, may be polled before worker thread is active
  m_driver_stats.driver_bus = NavAddr::Bus::N2000;
  m_driver_stats.driver_iface = m_params.GetStrippedDSPort();
  m_driver_stats.available = false;
 
  Open();
 
  wxMilliSleep(100);
  GetMfgCode();
 
  //  Initialize the device clearing all rx/tx filterx
  SendMgmtMsg(NGT_STARTUP_SEQ, sizeof(NGT_STARTUP_SEQ), 0x11, 0, NULL);
}
 
CommDriverN2KSerial::~CommDriverN2KSerial() { Close(); }
 
DriverStats CommDriverN2KSerial::GetDriverStats() const {
  if (m_closing) return m_driver_stats;
 
#ifndef ANDROID
  if (m_pSecondary_Thread)
    return m_pSecondary_Thread->GetStats();
  else
#endif
    return m_driver_stats;
}
 
bool CommDriverN2KSerial::Open() {
  wxString comx;
  comx = m_params.GetDSPort().AfterFirst(':');  // strip "Serial:"
 
  comx =
      comx.BeforeFirst(' ');  // strip off any description provided by Windows
 
#ifndef ANDROID
  //    Kick off the  RX thread
  SetSecondaryThread(new CommDriverN2KSerialThread(this, comx, m_BaudRate));
  SetThreadRunFlag(1);
  GetSecondaryThread()->Run();
#endif
 
  return true;
}
 
void CommDriverN2KSerial::Close() {
  wxLogMessage(wxString::Format("Closing N2K Driver %s", m_portstring.c_str()));
 
  m_stats_timer.Stop();
  m_closing = true;
 
  //    Kill off the Secondary RX Thread if alive
  if (m_pSecondary_Thread) {
    if (m_bsec_thread_active)  // Try to be sure thread object is still alive
    {
      wxLogMessage("Stopping Secondary Thread");
 
      m_Thread_run_flag = 0;
      int tsec = 10;
      while ((m_Thread_run_flag >= 0) && (tsec--)) wxSleep(1);
 
      wxString msg;
      if (m_Thread_run_flag < 0)
        msg.Printf("Stopped in %d sec.", 10 - tsec);
      else
        msg.Printf("Not Stopped after 10 sec.");
      wxLogMessage(msg);
    }
 
    m_pSecondary_Thread = NULL;
    m_bsec_thread_active = false;
  }
}
static uint64_t PayloadToName(const std::vector<unsigned char> payload) {
  uint64_t name;
  memcpy(&name, reinterpret_cast<const void*>(payload.data()), sizeof(name));
  return name;
}
 
bool CommDriverN2KSerial::SendMessage(std::shared_ptr<const NavMsg> msg,
                                      std::shared_ptr<const NavAddr> addr) {
  if (m_closing) return false;
  if (!msg) return false;
 
#ifndef ANDROID
 
  auto msg_n2k = std::dynamic_pointer_cast<const Nmea2000Msg>(msg);
  std::vector<uint8_t> load = msg_n2k->payload;
 
  uint64_t _pgn = msg_n2k->PGN.pgn;
  auto destination_address = std::static_pointer_cast<const NavAddr2000>(addr);
 
  tN2kMsg N2kMsg;  // automatically sets destination 255
  N2kMsg.SetPGN(_pgn);
  N2kMsg.Priority = msg_n2k->priority;
  if (destination_address) N2kMsg.Destination = destination_address->address;
 
  for (size_t i = 0; i < load.size(); i++) N2kMsg.AddByte(load.at(i));  // data
 
  const std::vector<uint8_t> acti_pkg = BufferToActisenseFormat(N2kMsg);
 
  // Create the internal message  and notify upper layers
  std::vector<unsigned char> msg_payload;
  for (size_t i = 2; i < acti_pkg.size() - 2; i++)
    msg_payload.push_back(acti_pkg[i]);
  auto name = PayloadToName(load);
  m_listener.Notify(
      std::make_shared<const Nmea2000Msg>(_pgn, msg_payload, GetAddress(name)));
 
  if (GetSecondaryThread()) {
    if (IsSecThreadActive()) {
      int retry = 10;
      while (retry) {
        if (GetSecondaryThread()->SetOutMsg(acti_pkg))
          return true;
        else
          retry--;
      }
      return false;  // could not send after several tries....
    } else
      return false;
  }
#endif
  return true;
}
 
void CommDriverN2KSerial::ProcessManagementPacket(
    std::vector<unsigned char>* payload) {
  if (payload->at(2) != 0xF2) {  // hearbeat
    // printf("    pl ");
    // for (unsigned int i = 0; i < payload->size(); i++)
    //  printf("%02X ", payload->at(i));
    // printf("\n");
  }
 
  switch (payload->at(2)) {
    case 0x47:
      m_bmg47_resp = true;
      break;
    case 0x01:
      m_bmg01_resp = true;
      break;
    case 0x4B:
      m_bmg4B_resp = true;
      break;
    case 0x041: {
      m_bmg41_resp = true;
      if (payload->at(3) == 0x02) {  // ASCII device_common_name
        std::string device_common_name;
        for (unsigned int i = 0; i < 32; i++) {
          device_common_name += payload->at(i + 14);
        }
        device_common_name += '\0';
        m_device_common_name = device_common_name;
      }
      break;
    }
    case 0x042: {
      m_bmg42_resp = true;
      unsigned char name[8];
      for (unsigned int i = 0; i < 8; i++) name[i] = payload->at(i + 15);
 
      memcpy((void*)&NAME, name, 8);
      // Extract the manufacturers code
      int* f1 = (int*)&NAME;
      int f1d = *f1;
      m_manufacturers_code = f1d >> 21;
      break;
    }
 
    default:
      break;
  }
}
 
void CommDriverN2KSerial::handle_N2K_SERIAL_RAW(
    CommDriverN2KSerialEvent& event) {
  auto p = event.GetPayload();
 
  std::vector<unsigned char>* payload = p.get();
 
  if (payload->at(0) == 0xA0) {
    ProcessManagementPacket(payload);
    return;
  }
 
  // If port INPUT is not set, filter the mesage here
  if (m_params.IOSelect != DS_TYPE_OUTPUT) {
    // extract PGN
    uint64_t pgn = 0;
    unsigned char* c = (unsigned char*)&pgn;
    *c++ = payload->at(3);
    *c++ = payload->at(4);
    *c++ = payload->at(5);
 
    auto name = PayloadToName(*payload);
    auto msg =
        std::make_shared<const Nmea2000Msg>(pgn, *payload, GetAddress(name));
 
    m_listener.Notify(std::move(msg));
  }
}
 
int CommDriverN2KSerial::GetMfgCode() {
  unsigned char request_name[] = {0x42};
  int ni = SendMgmtMsg(request_name, sizeof(request_name), 0x41, 2000,
                       &m_bmg42_resp);
  if (ni) return ni;  // Not responding, return error so upper retries.
  m_got_mfg_code = true;
  return 0;
}
 
int CommDriverN2KSerial::SendMgmtMsg(unsigned char* string, size_t string_size,
                                     unsigned char cmd_code, int timeout_msec,
                                     bool* response_flag) {
#ifndef ANDROID
  // Make a message
  int byteSum = 0;
  uint8_t CheckSum;
  std::vector<unsigned char> msg;
 
  msg.push_back(ESCAPE);
  msg.push_back(STARTOFTEXT);
  msg.push_back(0xA1);
  byteSum += 0xA1;
  msg.push_back(string_size);  // payload length
  byteSum += string_size;
 
  for (unsigned int i = 0; i < string_size; i++) {
    if (string[i] == ESCAPE) msg.push_back(string[i]);
    msg.push_back(string[i]);
    byteSum += string[i];
  }
 
  // checksum
  byteSum %= 256;
  CheckSum = (uint8_t)((byteSum == 0) ? 0 : (256 - byteSum));
  msg.push_back(CheckSum);
 
  msg.push_back(ESCAPE);
  msg.push_back(ENDOFTEXT);
 
  // send it out
 
  if (response_flag) *response_flag = false;  // prime the response detector
 
  // Send the msg
  bool bsent = false;
  bool not_done = true;
  int ntry_outer = 10;
  while (not_done) {
    if (GetSecondaryThread() && IsSecThreadActive()) {
      int retry = 10;
      while (retry) {
        if (GetSecondaryThread()->SetOutMsg(msg)) {
          bsent = true;
          not_done = false;
          break;
        } else
          retry--;
      }
    } else {
      wxMilliSleep(100);
      if (ntry_outer-- <= 0) not_done = false;
    }
  }
 
  if (!bsent) return 1;
 
  bool bOK = false;
  if (timeout_msec) {
    int timeout = timeout_msec;
    while (timeout > 0) {
      wxYieldIfNeeded();
      wxMilliSleep(100);
      if (response_flag) {
        if (*response_flag) {
          bOK = true;
          break;
        }
      }
      timeout -= 100;
    }
  } else
    bOK = true;
 
  if (!bOK) {
    // printf( "***Err-1\n");
    return 1;
  }
  // else
  // printf("***OK-1  %d\n", timeout);
#endif
  return 0;
}
 
int CommDriverN2KSerial::SetTXPGN(int pgn) {
  //  Enable PGN message
  unsigned char request_enable[] = {0x47, 0x00, 0x00, 0x00,  // pgn
                                    0x00, 0x01, 0xFF, 0xFF, 0xFF, 0xFF};
 
  int PGN = 0;
  unsigned char* c = (unsigned char*)&pgn;
  request_enable[1] = c[0];
  request_enable[2] = c[1];
  request_enable[3] = c[2];
 
  int aa = SendMgmtMsg(request_enable, sizeof(request_enable), 0x47, 2000,
                       &m_bmg47_resp);
  if (aa) return 0;  // Probably YDNU-02 device
 
  //  Commit message
  unsigned char request_commit[] = {0x01};
  int bb = SendMgmtMsg(request_commit, sizeof(request_commit), 0x01, 2000,
                       &m_bmg01_resp);
 
  // Activate message
  unsigned char request_activate[] = {0x4B};
  int cc = SendMgmtMsg(request_activate, sizeof(request_activate), 0x4B, 2000,
                       &m_bmg4B_resp);
 
  return 0;
}
void CommDriverN2KSerial::AddTxPGN(int pgn) {
  auto it = std::find(pgn_tx_list.begin(), pgn_tx_list.end(), pgn);
  if (it != pgn_tx_list.end())
    return;
  else {
    SetTXPGN(pgn);
    pgn_tx_list.push_back(pgn);
  }
}
 
#ifndef __ANDROID__
 
// Commonly used raw format is actually inherited from an old paketizing format:
// <10><02><application data><CRC (1)><10><03>
 
// Actisense application data, from NGT-1 to PC
// <data code=93><length (1)><priority (1)><PGN (3)><destination(1)><source
// (1)><time (4)><len (1)><data (len)>
 
// As applied to a real application data element, after extraction from packet
// format: 93 13 02 01 F8 01 FF 01 76 C2 52 00 08 08 70 EB 14 E8 8E 52 D2 BB 10
 
// length (1):      0x13
// priority (1);    0x02
// PGN (3):         0x01 0xF8 0x01
// destination(1):  0xFF
// source (1):      0x01
// time (4):        0x76 0xC2 0x52 0x00
// len (1):         0x08
// data (len):      08 70 EB 14 E8 8E 52 D2
// packet CRC:      0xBB
 
#define DS_RX_BUFFER_SIZE 4096
 
CommDriverN2KSerialThread::CommDriverN2KSerialThread(
    CommDriverN2KSerial* Launcher, const wxString& PortName,
    const wxString& strBaudRate)
    : m_out_que(OUT_QUEUE_LENGTH) {
  m_pParentDriver = Launcher;  // This thread's immediate "parent"
 
  m_PortName = PortName;
  m_FullPortName = "Serial:" + PortName;
 
  rx_buffer = new unsigned char[DS_RX_BUFFER_SIZE + 1];
 
  put_ptr = rx_buffer;  // local circular queue
  tak_ptr = rx_buffer;
 
  m_baud = 9600;  // default
  long lbaud;
  if (strBaudRate.ToLong(&lbaud)) m_baud = (int)lbaud;
  {
    std::lock_guard lock(m_stats_mutex);
    m_driver_stats.driver_bus = NavAddr::Bus::N2000;
    m_driver_stats.driver_iface = m_pParentDriver->m_params.GetStrippedDSPort();
    m_driver_stats.available = false;
  }
 
  Create();
}
 
CommDriverN2KSerialThread::~CommDriverN2KSerialThread() { delete[] rx_buffer; }
 
void CommDriverN2KSerialThread::OnExit() {}
 
DriverStats CommDriverN2KSerialThread::GetStats() const {
  std::lock_guard lock(m_stats_mutex);
  return m_driver_stats;
}
 
bool CommDriverN2KSerialThread::OpenComPortPhysical(const wxString& com_name,
                                                    int baud_rate) {
  try {
    m_serial.setPort(com_name.ToStdString());
    m_serial.setBaudrate(baud_rate);
    m_serial.open();
    m_serial.setTimeout(250, 250, 0, 250, 0);
  } catch (std::exception&) {
    // std::cerr << "Unhandled Exception while opening serial port: " <<
    // e.what() << std::endl;
  }
  return m_serial.isOpen();
}
 
void CommDriverN2KSerialThread::CloseComPortPhysical() {
  try {
    m_serial.close();
  } catch (std::exception&) {
    // std::cerr << "Unhandled Exception while closing serial port: " <<
    // e.what() << std::endl;
  }
  std::lock_guard lock(m_stats_mutex);
  m_driver_stats.available = false;
}
 
void CommDriverN2KSerialThread::SetGatewayOperationMode() {
  // For YDNU-02 device
  // From Device User Manual
  // Set the mode to "N2K"
  unsigned char config_string[] = {0x10, 0x02, 0xA1, 0x03, 0x11,
                                   0x02, 0x00, 0x49, 0x10, 0x03};
  // std::vector<byte>writeBuffer {DLE,STX,NGT_TX_CMD,0x03,0x11,0x02,0x00,0x49,
  // DLE,ETX};
 
  WriteComPortPhysical(config_string, 10);
}
 
void CommDriverN2KSerialThread::ThreadMessage(const wxString& msg) {
  //    Signal the main program thread
  //   OCPN_ThreadMessageEvent event(wxEVT_OCPN_THREADMSG, 0);
  //   event.SetSString(std::string(msg.mb_str()));
  //   if (gFrame) gFrame->GetEventHandler()->AddPendingEvent(event);
}
 
size_t CommDriverN2KSerialThread::WriteComPortPhysical(
    std::vector<unsigned char> msg) {
  return WriteComPortPhysical(msg.data(), msg.size());
}
 
size_t CommDriverN2KSerialThread::WriteComPortPhysical(unsigned char* msg,
                                                       size_t length) {
  if (!m_serial.isOpen()) return 0;
  try {
    size_t status = m_serial.write((uint8_t*)msg, length);
    if (status) m_serial.flushOutput();
    return status;
  } catch (std::exception& e) {
    DEBUG_LOG << "Unhandled Exception while writing to serial port: "
              << e.what();
  }
  return 0;
}
 
bool CommDriverN2KSerialThread::SetOutMsg(
    const std::vector<unsigned char>& msg) {
  if (!m_out_que.IsFull()) {
    m_out_que.Put(msg);
    return true;
  }
  return false;
}
 
#ifndef __WXMSW__
void* CommDriverN2KSerialThread::Entry() {
  bool not_done = true;
  bool nl_found = false;
  wxString msg;
  uint8_t rdata[2000];
  CircularBuffer<uint8_t> circle(DS_RX_BUFFER_SIZE);
  int ib = 0;
 
  //    Request the com port from the comm manager
  if (!OpenComPortPhysical(m_PortName, m_baud)) {
    wxString msg("NMEA input device open failed: ");
    msg.Append(m_PortName);
    ThreadMessage(msg);
    std::lock_guard lock(m_stats_mutex);
    m_driver_stats.available = false;
 
    // goto thread_exit; // This means we will not be trying to connect = The
    // device must be connected when the thread is created. Does not seem to be
    // needed/what we want as the reconnection logic is able to pick it up
    // whenever it actually appears (Of course given it appears with the
    // expected device name).
  } else {
    wxMilliSleep(100);
    std::lock_guard lock(m_stats_mutex);
    m_driver_stats.available = true;
    SetGatewayOperationMode();
  }
 
  m_pParentDriver->SetSecThreadActive();  // I am alive
 
  //    The main loop
  static size_t retries = 0;
 
  bool bInMsg = false;
  bool bGotESC = false;
  bool bGotSOT = false;
 
  while ((not_done) && (m_pParentDriver->m_Thread_run_flag > 0)) {
    if (TestDestroy()) not_done = false;  // smooth exit
 
    uint8_t next_byte = 0;
    int newdata = 0;
    if (m_serial.isOpen()) {
      try {
        newdata = m_serial.read(rdata, 1000);
      } catch (std::exception& e) {
        // std::cerr << "Serial read exception: " << e.what() << std::endl;
        std::lock_guard lock(m_stats_mutex);
        m_driver_stats.error_count++;
 
        if (10 < retries++) {
          // We timed out waiting for the next character 10 times, let's close
          // the port so that the reconnection logic kicks in and tries to fix
          // our connection.
          CloseComPortPhysical();
          retries = 0;
        }
      }
    } else {
      // Reconnection logic. Let's try to reopen the port while waiting longer
      // every time (until we simply keep trying every 2.5 seconds)
      // std::cerr << "Serial port seems closed." << std::endl;
      wxMilliSleep(250 * retries);
      CloseComPortPhysical();
      if (OpenComPortPhysical(m_PortName, m_baud)) {
        SetGatewayOperationMode();
        std::lock_guard lock(m_stats_mutex);
        m_driver_stats.available = true;
        retries = 0;
      } else if (retries < 10) {
        std::lock_guard lock(m_stats_mutex);
        m_driver_stats.available = false;
        retries++;
      }
    }
 
    if (newdata > 0) {
      std::lock_guard lock(m_stats_mutex);
      m_driver_stats.rx_count += newdata;
 
      for (int i = 0; i < newdata; i++) {
        circle.Put(rdata[i]);
      }
    }
 
    while (!circle.IsEmpty()) {
      if (ib >= DS_RX_BUFFER_SIZE) ib = 0;
      uint8_t next_byte = circle.Get();
 
      if (bInMsg) {
        if (bGotESC) {
          if (ESCAPE == next_byte) {
            rx_buffer[ib++] = next_byte;
            bGotESC = false;
          }
        }
 
        if (bGotESC && (ENDOFTEXT == next_byte)) {
          // Process packet
          //    Copy the message into a std::vector
 
          auto buffer = std::make_shared<std::vector<unsigned char>>(
              rx_buffer, rx_buffer + ib);
          std::vector<unsigned char>* vec = buffer.get();
 
          ib = 0;
          // tak_ptr = tptr;
          bInMsg = false;
          bGotESC = false;
 
          //           printf("raw ");
          //              for (unsigned int i = 0; i < vec->size(); i++)
          //                printf("%02X ", vec->at(i));
          //              printf("\n");
 
          // Message is finished
          // Send the captured raw data vector pointer to the thread's "parent"
          //  thereby releasing the thread for further data capture
          CommDriverN2KSerialEvent Nevent(wxEVT_COMMDRIVER_N2K_SERIAL, 0);
          Nevent.SetPayload(buffer);
          m_pParentDriver->AddPendingEvent(Nevent);
 
        } else {
          bGotESC = (next_byte == ESCAPE);
 
          if (!bGotESC) {
            rx_buffer[ib++] = next_byte;
          }
        }
      }
 
      else {
        if (STARTOFTEXT == next_byte) {
          bGotSOT = false;
          if (bGotESC) {
            bGotSOT = true;
          }
        } else {
          bGotESC = (next_byte == ESCAPE);
          if (bGotSOT) {
            bGotSOT = false;
            bInMsg = true;
 
            rx_buffer[ib++] = next_byte;
          }
        }
      }
    }  // if newdata > 0
 
    //      Check for any pending output message
#if 1
    bool b_qdata = !m_out_que.IsEmpty();
 
    while (b_qdata) {
      //  Take a copy of message
      std::vector<unsigned char> qmsg = m_out_que.Get();
 
      if (static_cast<size_t>(-1) == WriteComPortPhysical(qmsg) &&
          10 < retries++) {
        // We failed to write the port 10 times, let's close the port so that
        // the reconnection logic kicks in and tries to fix our connection.
        retries = 0;
        CloseComPortPhysical();
      }
 
      b_qdata = !m_out_que.IsEmpty();
    }  // while b_qdata
 
#endif
  }  // while ((not_done)
 
  // thread_exit:
  CloseComPortPhysical();
  m_pParentDriver->SetSecThreadInActive();  // I am dead
  m_pParentDriver->m_Thread_run_flag = -1;
 
  std::lock_guard lock(m_stats_mutex);
  m_driver_stats.available = false;
 
  return 0;
}
 
#else
void* CommDriverN2KSerialThread::Entry() {
  bool not_done = true;
  bool nl_found = false;
  wxString msg;
  CircularBuffer<uint8_t> circle(DS_RX_BUFFER_SIZE);
 
  //    Request the com port from the comm manager
  if (!OpenComPortPhysical(m_PortName, m_baud)) {
    wxString msg("NMEA input device open failed: ");
    msg.Append(m_PortName);
    ThreadMessage(msg);
    std::lock_guard lock(m_stats_mutex);
    m_driver_stats.available = false;
 
    // goto thread_exit; // This means we will not be trying to connect = The
    // device must be connected when the thread is created. Does not seem to be
    // needed/what we want as the reconnection logic is able to pick it up
    // whenever it actually appears (Of course given it appears with the
    // expected device name).
  } else {
    SetGatewayOperationMode();
    std::lock_guard lock(m_stats_mutex);
    m_driver_stats.available = true;
  }
 
  m_pParentDriver->SetSecThreadActive();  // I am alive
 
  //    The main loop
  static size_t retries = 0;
 
  bool bInMsg = false;
  bool bGotESC = false;
  bool bGotSOT = false;
 
  while ((not_done) && (m_pParentDriver->m_Thread_run_flag > 0)) {
    if (TestDestroy()) not_done = false;  // smooth exit
 
    uint8_t next_byte = 0;
    int newdata = -1;
    uint8_t rdata[2000];
 
    if (m_serial.isOpen()) {
      try {
        newdata = m_serial.read(rdata, 200);
      } catch (std::exception& e) {
        // std::cerr << "Serial read exception: " << e.what() << std::endl;
        if (10 < retries++) {
          // We timed out waiting for the next character 10 times, let's close
          // the port so that the reconnection logic kicks in and tries to fix
          // our connection.
          CloseComPortPhysical();
          retries = 0;
        }
      }
    } else {
      // Reconnection logic. Let's try to reopen the port while waiting longer
      // every time (until we simply keep trying every 2.5 seconds)
      // std::cerr << "Serial port seems closed." << std::endl;
      wxMilliSleep(250 * retries);
      CloseComPortPhysical();
      if (OpenComPortPhysical(m_PortName, m_baud)) {
        std::lock_guard lock(m_stats_mutex);
        m_driver_stats.available = true;
        SetGatewayOperationMode();
        retries = 0;
      } else if (retries < 10)
        retries++;
    }
 
    if (newdata > 0) {
      for (int i = 0; i < newdata; i++) {
        circle.Put(rdata[i]);
      }
    }
 
    while (!circle.IsEmpty()) {
      uint8_t next_byte = circle.Get();
 
      if (1) {
        if (bInMsg) {
          if (bGotESC) {
            if (ESCAPE == next_byte) {
              *put_ptr++ = next_byte;
              if ((put_ptr - rx_buffer) > DS_RX_BUFFER_SIZE)
                put_ptr = rx_buffer;
              bGotESC = false;
            } else if (ENDOFTEXT == next_byte) {
              // Process packet
              //    Copy the message into a std::vector
 
              auto buffer = std::make_shared<std::vector<unsigned char>>();
              std::vector<unsigned char>* vec = buffer.get();
 
              unsigned char* tptr;
              tptr = tak_ptr;
 
              while ((tptr != put_ptr)) {
                vec->push_back(*tptr++);
                if ((tptr - rx_buffer) > DS_RX_BUFFER_SIZE) tptr = rx_buffer;
              }
 
              tak_ptr = tptr;
              bInMsg = false;
              bGotESC = false;
 
              // Message is finished
              // Send the captured raw data vector pointer to the thread's
              // "parent"
              //  thereby releasing the thread for further data capture
              CommDriverN2KSerialEvent Nevent(wxEVT_COMMDRIVER_N2K_SERIAL, 0);
              Nevent.SetPayload(buffer);
              m_pParentDriver->AddPendingEvent(Nevent);
              std::lock_guard lock(m_stats_mutex);
              m_driver_stats.rx_count += vec->size();
            } else if (next_byte == STARTOFTEXT) {
              put_ptr = rx_buffer;
              bGotESC = false;
            } else {
              put_ptr = rx_buffer;
              bInMsg = false;
              bGotESC = false;
            }
 
          } else {
            bGotESC = (next_byte == ESCAPE);
 
            if (!bGotESC) {
              *put_ptr++ = next_byte;
              if ((put_ptr - rx_buffer) > DS_RX_BUFFER_SIZE)
                put_ptr = rx_buffer;
            }
          }
        }
 
        else {
          if (STARTOFTEXT == next_byte) {
            bGotSOT = false;
            if (bGotESC) {
              bGotSOT = true;
            }
          } else {
            bGotESC = (next_byte == ESCAPE);
            if (bGotSOT) {
              bGotSOT = false;
              bInMsg = true;
 
              *put_ptr++ = next_byte;
              if ((put_ptr - rx_buffer) > DS_RX_BUFFER_SIZE)
                put_ptr = rx_buffer;
            }
          }
        }
      }  // if newdata > 0
    }  // while
 
    //      Check for any pending output message
    bool b_qdata = !m_out_que.IsEmpty();
 
    while (!m_out_que.IsEmpty()) {
      //  Take a copy of message
      std::vector<unsigned char> qmsg = m_out_que.Get();
 
      if (static_cast<size_t>(-1) == WriteComPortPhysical(qmsg) &&
          10 < retries++) {
        // We failed to write the port 10 times, let's close the port so that
        // the reconnection logic kicks in and tries to fix our connection.
        retries = 0;
        CloseComPortPhysical();
      }
      std::lock_guard lock(m_stats_mutex);
      m_driver_stats.tx_count += qmsg.size();
    }
  }  // while ((not_done)
 
  // thread_exit:
  CloseComPortPhysical();
  m_pParentDriver->SetSecThreadInActive();  // I am dead
  m_pParentDriver->m_Thread_run_flag = -1;
 
  return 0;
}
 
#endif  //  wxmsw Entry()
 
#endif  // Android
 
//*****************************************************************************
// Actisense Format:
// <10><02><93><length (1)><priority (1)><PGN (3)><destination (1)><source
// (1)><time (4)><len (1)><data (len)><CRC (1)><10><03>
#define MaxActisenseMsgBuf 400
#define MsgTypeN2kTX 0x94
 
void AddByteEscapedToBuf(unsigned char byteToAdd, uint8_t& idx,
                         unsigned char* buf, int& byteSum);
 
static std::vector<unsigned char> BufferToActisenseFormat(tN2kMsg& msg) {
  unsigned long _PGN = msg.PGN;
  uint8_t msgIdx = 0;
  int byteSum = 0;
  uint8_t CheckSum;
  unsigned char ActisenseMsgBuf[MaxActisenseMsgBuf];
 
  ActisenseMsgBuf[msgIdx++] = ESCAPE;
  ActisenseMsgBuf[msgIdx++] = STARTOFTEXT;
  AddByteEscapedToBuf(MsgTypeN2kTX, msgIdx, ActisenseMsgBuf, byteSum);
  AddByteEscapedToBuf(msg.DataLen + 6, msgIdx, ActisenseMsgBuf,
                      byteSum);  // length does not include escaped chars
 
  AddByteEscapedToBuf(msg.Priority, msgIdx, ActisenseMsgBuf, byteSum);
  AddByteEscapedToBuf(_PGN & 0xff, msgIdx, ActisenseMsgBuf, byteSum);
  _PGN >>= 8;
  AddByteEscapedToBuf(_PGN & 0xff, msgIdx, ActisenseMsgBuf, byteSum);
  _PGN >>= 8;
  AddByteEscapedToBuf(_PGN & 0xff, msgIdx, ActisenseMsgBuf, byteSum);
  AddByteEscapedToBuf(msg.Destination, msgIdx, ActisenseMsgBuf, byteSum);
 
#if 0
  // For TX through Actisense compatible gateway, we skip "source" byte and msg time fields
  // Source
  AddByteEscapedToBuf(msg.Source,msgIdx,ActisenseMsgBuf,byteSum);
  // Time
  int _MsgTime = 0;
  AddByteEscapedToBuf(_MsgTime & 0xff,msgIdx,ActisenseMsgBuf,byteSum); _MsgTime>>=8;
  AddByteEscapedToBuf(_MsgTime & 0xff,msgIdx,ActisenseMsgBuf,byteSum); _MsgTime>>=8;
  AddByteEscapedToBuf(_MsgTime & 0xff,msgIdx,ActisenseMsgBuf,byteSum); _MsgTime>>=8;
  AddByteEscapedToBuf(_MsgTime & 0xff,msgIdx,ActisenseMsgBuf,byteSum);
 
#endif
 
  AddByteEscapedToBuf(msg.DataLen, msgIdx, ActisenseMsgBuf, byteSum);
 
  for (int i = 0; i < msg.DataLen; i++)
    AddByteEscapedToBuf(msg.Data[i], msgIdx, ActisenseMsgBuf, byteSum);
  byteSum %= 256;
 
  CheckSum = (uint8_t)((byteSum == 0) ? 0 : (256 - byteSum));
  ActisenseMsgBuf[msgIdx++] = CheckSum;
  if (CheckSum == ESCAPE) ActisenseMsgBuf[msgIdx++] = CheckSum;
 
  ActisenseMsgBuf[msgIdx++] = ESCAPE;
  ActisenseMsgBuf[msgIdx++] = ENDOFTEXT;
 
  std::vector<unsigned char> rv;
  for (unsigned int i = 0; i < msgIdx; i++) rv.push_back(ActisenseMsgBuf[i]);
 
  return rv;
}