Merge pull request #248 from sparkfun/revert-243-ring-buffer

Revert "Validate the RTCM and NMEA message flowing to and from the GNSS"

Author: nseidle

Firmware/RTK_Surveyor/Crc24q.ino

@@ -154,6 +154,108 @@ void ntripServerResponse(char * response, size_t maxLength)
   *response = '\0';
 }
 
+//Parse the RTCM transport data
+bool ntripServerRtcmMessage(uint8_t data)
+{
+  static uint16_t bytesRemaining;
+  static byte crcState = RTCM_TRANSPORT_STATE_WAIT_FOR_PREAMBLE_D3;
+  static uint16_t length;
+  static uint16_t message;
+  static bool sendMessage = false;
+
+  //
+  //    RTCM Standard 10403.2 - Chapter 4, Transport Layer
+  //
+  //    |<------------- 3 bytes ------------>|<----- length ----->|<- 3 bytes ->|
+  //    |                                    |                    |             |
+  //    +----------+--------+----------------+---------+----------+-------------+
+  //    | Preamble |  Fill  | Message Length | Message |   Fill   |   CRC-24Q   |
+  //    |  8 bits  | 6 bits |    10 bits     |  n-bits | 0-7 bits |   24 bits   |
+  //    |   0xd3   | 000000 |   (in bytes)   |         |   zeros  |             |
+  //    +----------+--------+----------------+---------+----------+-------------+
+  //    |                                                                       |
+  //    |<-------------------------------- CRC -------------------------------->|
+  //
+
+  switch (crcState)
+  {
+    //Wait for the preamble byte (0xd3)
+    case RTCM_TRANSPORT_STATE_WAIT_FOR_PREAMBLE_D3:
+      sendMessage = false;
+      if (data == 0xd3)
+      {
+        crcState = RTCM_TRANSPORT_STATE_READ_LENGTH_1;
+        sendMessage = (ntripServerState == NTRIP_SERVER_CASTING);
+      }
+      break;
+
+    //Read the upper two bits of the length
+    case RTCM_TRANSPORT_STATE_READ_LENGTH_1:
+      length = data << 8;
+      crcState = RTCM_TRANSPORT_STATE_READ_LENGTH_2;
+      break;
+
+    //Read the lower 8 bits of the length
+    case RTCM_TRANSPORT_STATE_READ_LENGTH_2:
+      length |= data;
+      bytesRemaining = length;
+      crcState = RTCM_TRANSPORT_STATE_READ_MESSAGE_1;
+      break;
+
+    //Read the upper 8 bits of the message number
+    case RTCM_TRANSPORT_STATE_READ_MESSAGE_1:
+      message = data << 4;
+      bytesRemaining -= 1;
+      crcState = RTCM_TRANSPORT_STATE_READ_MESSAGE_2;
+      break;
+
+    //Read the lower 4 bits of the message number
+    case RTCM_TRANSPORT_STATE_READ_MESSAGE_2:
+      message |= data >> 4;
+      bytesRemaining -= 1;
+      crcState = RTCM_TRANSPORT_STATE_READ_DATA;
+      break;
+
+    //Read the rest of the message
+    case RTCM_TRANSPORT_STATE_READ_DATA:
+      bytesRemaining -= 1;
+      if (bytesRemaining <= 0)
+        crcState = RTCM_TRANSPORT_STATE_READ_CRC_1;
+      break;
+
+    //Read the upper 8 bits of the CRC
+    case RTCM_TRANSPORT_STATE_READ_CRC_1:
+      crcState = RTCM_TRANSPORT_STATE_READ_CRC_2;
+      break;
+
+    //Read the middle 8 bits of the CRC
+    case RTCM_TRANSPORT_STATE_READ_CRC_2:
+      crcState = RTCM_TRANSPORT_STATE_READ_CRC_3;
+      break;
+
+    //Read the lower 8 bits of the CRC
+    case RTCM_TRANSPORT_STATE_READ_CRC_3:
+      crcState = RTCM_TRANSPORT_STATE_CHECK_CRC;
+      break;
+  }
+
+  //Check the CRC
+  if (crcState == RTCM_TRANSPORT_STATE_CHECK_CRC)
+  {
+    crcState = RTCM_TRANSPORT_STATE_WAIT_FOR_PREAMBLE_D3;
+
+    //Account for this message
+    rtcmPacketsSent++;
+
+    //Display the RTCM message header
+    if (settings.enablePrintNtripServerRtcm && (!inMainMenu))
+      Serial.printf ("    Message %d, %2d bytes\r\n", message, 3 + 1 + length + 3);
+  }
+
+  //Let the upper layer know if this message should be sent
+  return sendMessage && (ntripServerState == NTRIP_SERVER_CASTING);
+}
+
 //Update the state of the NTRIP server state machine
 void ntripServerSetState(byte newState)
 {
@@ -233,83 +335,29 @@ void ntripServerProcessRTCM(uint8_t incoming)
 #ifdef  COMPILE_WIFI
   if (online.rtc)
   {
-    static PARSE_STATE parseState;
+    //Timestamp the RTCM messages
+    currentMilliseconds = millis();
+    if (settings.enablePrintNtripServerRtcm
+        && (!inMainMenu)
+        && ((currentMilliseconds - previousMilliseconds) > 1))
+    {
+      //         1         2         3
+      //123456789012345678901234567890
+      //YYYY-mm-dd HH:MM:SS.xxxrn0
+      struct tm timeinfo = rtc.getTimeStruct();
+      char timestamp[30];
+      strftime(timestamp, sizeof(timestamp), "%Y-%m-%d %H:%M:%S", &timeinfo);
+      Serial.printf("RTCM: %s.%03ld\r\n", timestamp, rtc.getMillis());
+    }
+    previousMilliseconds = currentMilliseconds;
 
     //Parse the RTCM message
-    if (parseNmeaAndRtcmMessages(&parseState, incoming, (ntripServerState == NTRIP_SERVER_CASTING)))
+    if (ntripServerRtcmMessage(incoming))
     {
       ntripServer->write(incoming); //Send this byte to socket
       ntripServerBytesSent++;
       ntripServerTimer = millis();
       online.txNtripDataCasting = true;
-
-      //Timestamp the RTCM messages
-      currentMilliseconds = millis();
-      if (settings.enablePrintNtripServerRtcm
-          && parseState.rtcmPackets
-          && (!inMainMenu)
-          && ((currentMilliseconds - previousMilliseconds) >= 1000))
-      {
-        //         1         2         3
-        //123456789012345678901234567890
-        //YYYY-mm-dd HH:MM:SS.xxxrn0
-        struct tm timeinfo = rtc.getTimeStruct();
-        char timestamp[30];
-        strftime(timestamp, sizeof(timestamp), "%Y-%m-%d %H:%M:%S", &timeinfo);
-        Serial.printf("RTCM: %s.%03ld\r\n", timestamp, rtc.getMillis());
-        previousMilliseconds += 1000;
-      }
-
-      //Update the RTCM message count
-      rtcmPacketsSent += parseState.rtcmPackets;
-      parseState.rtcmPackets = 0;
-
-      //Display the RTCM message header
-      if (settings.enablePrintNtripServerRtcm && (!inMainMenu))
-      {
-        if (parseState.invalidByte)
-        {
-          Serial.printf ("    Invalid byte: 0x%02x\r\n", incoming);
-          parseState.invalidByte = false;
-        }
-        if (parseState.printMessageNumber)
-        {
-          parseState.printMessageNumber = false;
-          if (parseState.invalidRtcmCrc)
-          {
-            parseState.invalidRtcmCrc = false;
-            Serial.printf("    RTCM %d, %2d bytes, bad CRC, computed 0x%06x, sent 0x%02x%02x%02x\r\n",
-                          parseState.messageNumber,
-                          3 + 1 + parseState.length + 3,
-                          parseState.rtcmCrc,
-                          parseState.crcByte[0],
-                          parseState.crcByte[1],
-                          parseState.crcByte[2]);
-          }
-          else
-            Serial.printf("    RTCM %d, %2d bytes\r\n",
-                          parseState.messageNumber,
-                          3 + 1 + parseState.length + 3);
-        }
-        if (parseState.printMessageName)
-        {
-          parseState.printMessageName = false;
-          if (parseState.invalidNmeaChecksum)
-          {
-            parseState.invalidNmeaChecksum = false;
-            Serial.printf("    NMEA %s, %2d bytes, bad checksum, computed 0x%02x, sent 0x%c%c\r\n",
-                          parseState.messageName,
-                          parseState.length,
-                          parseState.nmeaChecksum,
-                          parseState.checksumByte1,
-                          parseState.checksumByte2);
-          }
-          else
-            Serial.printf("    NMEA %s, %2d bytes\r\n",
-                          parseState.messageName,
-                          parseState.length);
-        }
-      }
     }
 
     //Indicate that the GNSS is providing correction data