function decode($datafile)
{
	global $db;
	global $LOG_END;
	global $fh;
	global $pos;
	global $length;

	$fh = fopen($datafile, "r");
	$time = time();
	$csvfile = "log/" . $time . ".csv";
	$pkmlfile = "log/" . $time . "p.kml";
	$skmlfile = "log/" . $time . "s.kml";
	log_line_to_db("#LOG_START", $db);
	
	$RETRY_BLOCK_SIZE = 16;
	$LOG_END = "0706010000BBBBBBBB";
	$ENDING = "BBBBBBBB";
	$HEADER_LENGTH = 1056;
	$NEW_SET_BEGIN = "AAAAAAAAAAAAAA";
	$ZERO = "00000000";
	$FFFF = "FFFFFFFF";

	$results = array();

	$size = hexdec(fread($fh, 16));
	echo "format=" . $format = (fread($fh, 16));
	echo "\n";

	if(is_int($format)) $format = dechex($format);
	$length = get_bytes_per_line($format) * 2;
	$datasize = filesize($datafile);
	$pos = 0;

	$line = resync("");
	
	$line_number = 0;
	$continue = true;

	for(;;)
	{
		//if($line_number == 0) echo "line = " . $line . "\n\n\n"; //break;
		if(strlen($line) < $length) break;
		if(substr($line, 0, strlen($NEW_SET_BEGIN)) == $NEW_SET_BEGIN || preg_match("/^[A-F0-9]{18}43000000002A/", substr($line, 0, 32)))
		{
			$line = resync($line);
			//echo "line = " . $line . "\n\n\n"; //break;
//			$results[] = "#LOG_START";
//			$pos += 32;
//			$waypoint = fread($fh, 32);
//			echo $line . " " . $waypoint . "\n\n\n";
			log_line_to_csv("#LOG_START", $csvfile);
			log_line_to_kml("#LOG_START", $pkmlfile, $skmlfile);
			log_line_to_db("#LOG_START", $db);
			continue;
		}
		else if(substr($line, 0, strlen($FFFF)) == $FFFF)
		{
			$tries = ($HEADER_LENGTH + $length) / ($RETRY_BLOCK_SIZE / 2);
			while((($found = strpos($line, $ENDING)) === false) && $tries-- > 0)
			{
				//echo $tries . " + " . $line . "\n";
				$pos += $RETRY_BLOCK_SIZE;
				$line = substr($line, $RETRY_BLOCK_SIZE) . fread($fh, $RETRY_BLOCK_SIZE);
				if(strlen($line) < $length) break;
			}
			if($found !== false)
			{
				$extra = $length - ($found + strlen($ENDING));
				if($extra > 0) $line = substr($line, $extra) . fread($fh, $extra);
				if(strlen($line) < $length) break;
			}
			else
			{
				break;
			}
		}
		else
		{
			$tries = $HEADER_LENGTH + length;
			while((($result = decode_line($line, $format)) == false) && $tries-- > 0)
			{
				$pos += 2;
				$line = substr($line, 2) . fread($fh, 2);
				if(strlen($line) < $length) break;

				if($error) echo "."; else echo "Error!  Attempting to resync... ";
				$error = true;

				//$results[] = "#ERROR";
				//echo "error at line $line_number (0x" . dechex($pos) . ")\n";
				//echo "   " . $line . "\n";
				break;
			}
			if($error && $result !== false)
			{
				echo "Recovered!";
				$error = false;
			}
			if($result != false)
			{
//				$results[] = $result;
				log_line_to_csv($result, $csvfile);
				log_line_to_db($result, $db);
				log_line_to_kml($result, $pkmlfile, $skmlfile);
			}
			$pos += $length;
			if($pos + $length > $datasize) break;
		}
		$line_number++;
		$line = fread($fh, $length);
	}
	echo "\n";
	fclose($fh);
	log_line_to_kml("#END", $pkmlfile, $skmlfile);
	return $results;
}

function resync($block)
{
	global $LOG_END;
	global $fh;
	global $pos;
	global $length;

	$block_size = strlen($LOG_END);
	$pos += $block_size; //strpos($data, $LOG_END) + strlen($LOG_END);
	$tries = 2048;
	$return = "";
	if(strlen($block) < $block_size) $block .= $return = fread($fh, $block_size - strlen($block));
	while((($found = strpos($block, $LOG_END)) === false) && $tries-- > 0)
	{
		//echo $tries . " " . $block . "\n";
		$pos += 2;
		$return .= $block = substr($block, 1) . fread($fh, 1);
	}
	if($found > strlen($block) - $block_size) $amount = $length - $found; else $amount = $length;
	$line = fread($fh, $amount);
	return $line;
}

function decode_line($line, $format)
{
	global $LOG, $LOGC;

	// Convert the hex-encoded string to a byte array //
	$bytes = array();
	for($i = 0; $i < strlen($line); $i += 2)
	{
		$bytes[] = hexdec($line{$i} . $line{$i + 1});
	}
	
	// Validate checksum //
	$csum = $bytes[count($bytes) - 1];
	$bytes = array_slice($bytes, 0, count($bytes) - 2);
	$chk = 0;
	foreach($bytes as $byte) $chk ^= $byte;
	if($chk != $csum) return false;
	
	// Get the list of fields in the correct order //
	$log_mask = $LOG;
	asort($LOG);
	$logformat = hexdec($format);
	$fields = array();
	foreach($log_mask as $name => $mask)
	{
		if($logformat & $mask) $fields[] = $name;
	}

	// Parse the data //
	$result = array();
	$addr = 0;
	foreach($fields as $field)
	{
		$str = "";
		$part = array_slice($bytes, $addr, $LOGC[$field]['size']);
		foreach($part as $byte) $str .= chr($byte);
		$val = unpack($LOGC[$field]['type'], $str);
		$result[$field] = $val[1];
		$addr += $LOGC[$field]['size'];
	}

	return $result;
}

function get_bytes_per_line($format)
{
	global $LOG, $LOGC;
	
	$log_mask = $LOG;
	asort($LOG);
	$logformat = hexdec($format);
	$fields = array();
	foreach($log_mask as $name => $mask)
	{
		if($logformat & $mask) $fields[] = $name;
	}
	$length = 2;
	foreach($fields as $field) $length += $LOGC[$field]['size'];

	return $length;
}

quote:

---

Originally posted by elijahparker

Here's my code that is currently working. I would do a bit differently now that I know more about the protocol, but this works and I've built a lot on top of it. One thing is doesn't allow which I have since learned is possible is sending multiple command at once and then receiving and confirming the multiple replies. This isn't important with my software so much, but still would have been nice.

---