Function parse

app/rcc/scripts/parser/js/sirf_binary.js:183–223

* Parses a SiRF binary message frame into the predefined array structure. * * SiRF binary message structure: * Bytes 0-1: Start sequence (0xA0 0xA2) * Bytes 2-3: Payload length (big-endian, 15 bits) * Byte 4: Message ID * Bytes 5-n: Payload data * Bytes n+1-n+2: Check

(frame)

 * @returns {array} Array of values mapped according to messageIdMap
 */
function parse(frame) {
  if (frame.length < 5)
    return parsedValues;

  var payloadLength = ((frame[0] & 0x7F) << 8) | frame[1];

  if (frame.length < 2 + payloadLength + 2) {
    console.error("Incomplete SiRF frame");
    return parsedValues;
  }

  var messageId = frame[2];

  var payload = [];
  for (var i = 2; i < 2 + payloadLength; i++)
    payload.push(frame[i]);

  var checksumOffset   = 2 + payloadLength;
  var receivedChecksum = ((frame[checksumOffset] & 0x7F) << 8) | frame[checksumOffset + 1];

  if (!validateChecksum(payload, receivedChecksum)) {
    console.error("SiRF checksum validation failed");
    return parsedValues;
  }

  if (!messageIdMap.hasOwnProperty(messageId))
    return parsedValues;

  var config = messageIdMap[messageId];

  try {
    var values = config.parser(payload.slice(1));
    for (var i = 0; i < values.length && i < config.indices.length; i++)
      parsedValues[config.indices[i]] = values[i];
  }
  catch (e) {
    console.error("SiRF parsing error:", e.message);
  }

  return parsedValues;
}