comm_can_util.h

/***************************************************************************
 *
 * Project:  OpenCPN
 * Purpose:  Low-level utility functions for socketcan support.
 * Author:   David Register, Alec Leamas
 *
 ***************************************************************************
 *   Copyright (C) 2024 by David Register, 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, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,  USA.         *
 **************************************************************************/
 
#ifndef _COMMCANUTIL_H
#define _COMMCANUTIL_H
 
#include <memory>
#include <string>
 
#include <wx/datetime.h>
 
#if !defined(__WXMSW__) && !defined(__WXMAC__)
#include <linux/can.h>
#include <linux/can/raw.h>
#endif
 
#ifdef __WXMSW__
#define CAN_MAX_DLEN 8
 
struct can_frame {
  uint32_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */
  uint8_t can_dlc; /* frame payload length in byte (0 .. 8) */
  uint8_t data[CAN_MAX_DLEN];
};
#endif
 
#if defined(__WXMAC__)
#define CAN_MAX_DLEN 8
 
struct can_frame {
  uint32_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */
  uint8_t can_dlc; /* frame payload length in byte (0 .. 8) */
  uint8_t data[CAN_MAX_DLEN];
};
#endif
 
unsigned long BuildCanID(int priority, int source, int destination, int pgn);
bool IsFastMessagePGN(unsigned pgn);
 
class CanHeader {
public:
  CanHeader();
  CanHeader(can_frame frame);
 
  bool IsFastMessage() const;
 
  unsigned char priority;
  unsigned char source;
  unsigned char destination;
  int pgn;
};
 
class FastMessageMap {
public:
  class Entry {
  public:
    Entry()
        : time_arrived(wxDateTime::Now()),
          sid(0),
          expected_length(0),
          cursor(0) {}
 
    wxDateTime time_arrived;  
 
    CanHeader header;
 
    unsigned int sid;
 
    unsigned int expected_length;  
    unsigned int cursor;  
    std::vector<unsigned char> data;  
  };
 
  FastMessageMap() : dropped_frames(0), last_gc_run(wxDateTime::Now()) {}
 
  Entry operator[](int i) const { return entries[i]; }  
  Entry& operator[](int i) { return entries[i]; }       
 
  int FindMatchingEntry(const CanHeader header, const unsigned char sid);
 
  int AddNewEntry(void);
 
  bool InsertEntry(const CanHeader header, const unsigned char* data,
                   int index);
 
  bool AppendEntry(const CanHeader hdr, const unsigned char* data, int index);
 
  void Remove(int pos);
 
  std::vector<Entry> entries;
 
private:
  bool IsEntryExpired(unsigned int i);
  int GarbageCollector(void);
  void CheckGc();
 
  int dropped_frames;
  wxDateTime last_gc_run;
  wxDateTime dropped_frame_time;
};
 
#endif  // guard