src/marnav/seatalk/message_51.cpp

   1 #include <marnav/seatalk/message_51.hpp>
   2 #include <marnav/math/floatingpoint.hpp>
   3
   4 namespace marnav::seatalk
   5 {
   6
   7 message_51::message_51()
   8         : message(ID)
   9 {
  10 }
  11
  12 std::unique_ptr<message> message_51::parse(const raw & data)
  13 {
  14         check_size(data, SIZE);
  15
  16         std::unique_ptr<message> result = std::make_unique<message_51>();
  17         auto & msg = static_cast<message_51 &>(*result);
  18
  19         // 51  Z2  XX  YY  YY
  20         // raw  1   2   3   4
  21
  22         const uint32_t degrees = data[2];
  23         uint32_t m = 0;
  24         m += data[3];
  25         m <<= 8;
  26         m += data[4];
  27
  28         const uint32_t minutes = (m & 0x7fff) / 100;
  29         const uint32_t seconds = (((m & 0x7fff) % 100) * 60) / 100;
  30         const geo::longitude::hemisphere hemisphere
  31                 = (m & 0x8000) ? geo::longitude::hemisphere::east : geo::longitude::hemisphere::west;
  32
  33         msg.lon_ = geo::longitude{degrees, minutes, seconds, hemisphere};
  34
  35         // deliberately ignored 'Z'
  36
  37         return result;
  38 }
  39
  40 raw message_51::get_data() const
  41 {
  42         uint16_t m = 0;
  43         m += lon_.minutes() * 100;
  44         m += math::float_cast<decltype(m)>((lon_.seconds() * 100) / 60);
  45         if (lon_.hem() == geo::longitude::hemisphere::east)
  46                 m |= 0x8000;
  47
  48         return raw{static_cast<uint8_t>(ID), 0x02, static_cast<uint8_t>(lon_.degrees() & 0xff),
  49                 static_cast<uint8_t>((m >> 8) & 0xff), static_cast<uint8_t>((m >> 0) & 0xff)};
  50 }
  51 }