LongMessageService.h

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// Copyright (C) Sven Rosvall (sven@rosvall.ie)
// This file is part of VLCB-Arduino project on https://github.com/SvenRosvall/VLCB-Arduino
// Licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
// The full licence can be found at: http://creativecommons.org/licenses/by-nc-sa/4.0/
 
#pragma once
 
#include "Service.h"
#include <vlcbdefs.hpp>
 
namespace VLCB
{
 
const int LONG_MESSAGE_DEFAULT_DELAY = 20;      // delay in milliseconds between sending successive long message fragments
const int LONG_MESSAGE_RECEIVE_TIMEOUT = 5000;  // timeout waiting for next long message packet
const int NUM_EX_CONTEXTS = 4;                  // number of send and receive contexts for extended implementation = number of concurrent messages
const int EX_BUFFER_LEN = 64;                   // size of extended send and receive buffers
 
//
//
 
enum {
  LONG_MESSAGE_INCOMPLETE = 0,
  LONG_MESSAGE_COMPLETE,
  LONG_MESSAGE_SEQUENCE_ERROR,
  LONG_MESSAGE_TIMEOUT_ERROR,
  LONG_MESSAGE_CRC_ERROR,
  LONG_MESSAGE_TRUNCATED
};
 
struct VlcbMessage;
 
//
//
class LongMessageService : public Service
{
 
public:
 
  virtual void process() override;
  virtual void processAction(const Action &action) override;
  bool sendLongMessage(const void *msg, const unsigned int msg_len, const byte stream_id);
  void subscribe(byte *stream_ids, const byte num_stream_ids, void *receive_buffer, const unsigned int receive_buffer_len, void (*messagehandler)(void *fragment, const unsigned int fragment_len, const byte stream_id, const byte status));
  virtual void processReceivedMessageFragment(const VlcbMessage *frame);
  bool is_sending();
  void setDelay(byte delay_in_millis);
  void setTimeout(unsigned int timeout_in_millis);
 
  virtual VlcbServiceTypes getServiceID() const override { return SERVICE_ID_STREAMING; }
  virtual byte getServiceVersionID() const override { return 1; }
 
protected:
 
  void handleMessage(const VlcbMessage *msg);
  bool sendMessageFragment(VlcbMessage *frame);
 
  bool _is_receiving = false;
  byte *_send_buffer, *_receive_buffer;
  byte _send_stream_id = 0, _receive_stream_id = 0, *_stream_ids = NULL, _num_stream_ids = 0;
  byte _msg_delay = LONG_MESSAGE_DEFAULT_DELAY;
  unsigned int _send_buffer_len = 0, _incoming_message_length = 0, _receive_buffer_len = 0, _receive_buffer_index = 0;
  unsigned int _send_buffer_index = 0, _incoming_message_crc = 0, _incoming_bytes_received = 0;
  unsigned int _receive_timeout = LONG_MESSAGE_RECEIVE_TIMEOUT, _send_sequence_num = 0, _expected_next_receive_sequence_num = 0;
  unsigned long _last_fragment_sent = 0UL, _last_fragment_received = 0UL;
 
  void (*_messagehandler)(void *fragment, const unsigned int fragment_len, const byte stream_id, const byte status);        // user callback function to receive long message fragments
};
 

 
// send and receive contexts
 
struct receive_context_t {
  bool in_use;
  byte receive_stream_id;
  byte *buffer;
  unsigned int receive_buffer_index, incoming_bytes_received, incoming_message_length, expected_next_receive_sequence_num, incoming_message_crc;
  unsigned long last_fragment_received;
};
 
struct send_context_t {
  bool in_use;
  byte send_stream_id, msg_delay;
  byte *buffer;
  unsigned int send_buffer_len, send_buffer_index, send_sequence_num;
  unsigned long last_fragment_sent;
};
 
//
//
class LongMessageServiceEx : public LongMessageService
{
public:
 
  bool allocateContexts(byte num_receive_contexts = NUM_EX_CONTEXTS, unsigned int receive_buffer_len = EX_BUFFER_LEN, byte num_send_contexts = NUM_EX_CONTEXTS);
  bool sendLongMessage(const void *msg, const unsigned int msg_len, const byte stream_id);
  virtual void process() override;
  void subscribe(byte *stream_ids, const byte num_stream_ids, void (*messagehandler)(void *msg, unsigned int msg_len, byte stream_id, byte status));
  virtual void processReceivedMessageFragment(const VlcbMessage *frame);
  byte is_sending();
  void use_crc(bool use_crc);
 
private:
 
  bool _use_crc = false;
  byte _num_receive_contexts = NUM_EX_CONTEXTS, _num_send_contexts = NUM_EX_CONTEXTS;
  receive_context_t **_receive_context = NULL;
  send_context_t **_send_context = NULL;
};
 
}