src/marnav/io/nmea_reader.cpp

   1 #include "nmea_reader.hpp"
   2 #include <algorithm>
   3 #include <marnav/utils/unique.hpp>
   4
   5 namespace marnav
   6 {
   7 namespace io
   8 {
   9 nmea_reader::~nmea_reader()
  10 {
  11 }
  12
  13 /// Initializes the reader, opens the device (if valid).
  14 ///
  15 /// @param[in] d The device to read data from, will be opened.
  16 nmea_reader::nmea_reader(std::unique_ptr<device> && d)
  17         : raw(0)
  18         , dev(std::move(d))
  19 {
  20         sentence.reserve(nmea::sentence::max_length + 1);
  21         if (dev)
  22                 dev->open();
  23 }
  24
  25 void nmea_reader::close()
  26 {
  27         if (dev)
  28                 dev->close();
  29         dev.reset();
  30 }
  31
  32 /// Reads data from the device.
  33 ///
  34 /// @retval true  Success.
  35 /// @retval false End of file.
  36 /// @exception std::runtime_error The device was invalid or read error.
  37 bool nmea_reader::read_data()
  38 {
  39         if (!dev)
  40                 throw std::runtime_error{"device invalid"};
  41         int rc = dev->read(&raw, sizeof(raw));
  42         if (rc == 0)
  43                 return false;
  44         if (rc < 0)
  45                 throw std::runtime_error{"read error"};
  46         if (rc != sizeof(raw))
  47                 throw std::runtime_error{"read error"};
  48         return true;
  49 }
  50
  51 /// Processes the data read from the device.
  52 ///
  53 /// @exception std::length_error Too many characters read for the sentence.
  54 ///   Maybe the end of line was missed or left out.
  55 void nmea_reader::process_nmea()
  56 {
  57         switch (raw) {
  58                 case '\r':
  59                         break;
  60                 case '\n': // end of sentence
  61                         process_sentence(sentence);
  62                         sentence.clear();
  63                         break;
  64                 default:
  65                         // ignore invalid characters. if this makes the sentence incomplete,
  66                         // the sentence would have been invalid anyway. the result will be
  67                         // an invalid sentence or a std::length_error.
  68                         if ((raw <= 32) || (raw >= 127))
  69                                 return;
  70
  71                         if (sentence.size() > nmea::sentence::max_length)
  72                                 throw std::length_error{"sentence size to large. receiving NMEA data?"};
  73                         sentence += raw;
  74                         break;
  75         }
  76 }
  77
  78 /// Reads data from the device and processes it. If a complete NMEA
  79 /// sentence was received the method process_message will be executed.
  80 /// This method automatcially synchronizes with NMEA data.
  81 ///
  82 /// @retval true  Success.
  83 /// @retval false End of file.
  84 /// @exception std::runtime_error Device or processing error.
  85 /// @exception std::length_error Synchronization issue.
  86 bool nmea_reader::read()
  87 {
  88         if (!read_data())
  89                 return false;
  90         process_nmea();
  91         return true;
  92 }
  93 }
  94 }