[driver] Successful checksum handling (still work to do on parser)

src/SeatracDriver.cpp

@@ -22,9 +22,11 @@ SeatracDriver::SeatracDriver(const IoServicePtr& ioService,
 
 void SeatracDriver::on_read(ReadBuffer& buffer, size_t byteCount)
 {
+    std::cout << "Received " << byteCount << " bytes." << std::endl;
     std::istream is(&buffer);
 
     char start = is.get();
+    std::cout << start << std::endl;
     if(start != '$') {
         std::ostringstream oss;
         oss << "Invalid data line (no starting character) :\n    "
@@ -32,17 +34,29 @@ void SeatracDriver::on_read(ReadBuffer& buffer, size_t byteCount)
         for(int i = 0; i < byteCount - 1; i++) {
             oss << (char)is.get();
         }
-        throw std::runtime_error(oss.str());
+        //throw std::runtime_error(oss.str());
+        std::cerr << oss.str() << std::endl;
     }
-
+    
+    // conversion from pair of ascii character to a 8bit value
+    auto fromAscii = [](char c) { return (uint8_t)(c >= 'A') ? (c - 'A' + 10) : (c - '0'); };
+    data_.resize((byteCount - 7) / 2);
     uint16_t checksum = 0;
-    data_.resize(byteCount - 7);
     for(auto& v : data_) {
-        v = is.get();
-        crc16_update(checksum, v);
+         v  = fromAscii(is.get()) << 4;
+         v += fromAscii(is.get());
+         crc16_update(checksum, v);
     }
 
-    //cout << "Checksum
+    uint16_t c = 0;
+    c  = fromAscii(is.get()) << 4;
+    c += fromAscii(is.get());
+    c += fromAscii(is.get()) << 12;
+    c += fromAscii(is.get()) << 8;
+
+    std::cout << std::hex << checksum << std::dec << std::endl;
+    std::cout << std::hex << c        << std::dec << std::endl;
+    std::cout << (int)is.get() << " " << (int)is.get() << std::endl;
 }
 
 }; //namespace seatrac