Add identifiable packets through a counter (#272)

Author: hrfarmer

pysquared/hardware/radio/packetizer/packet_manager.py

@@ -2,6 +2,7 @@
 import time
 
 from ....logger import Logger
+from ....nvm.counter import Counter
 from ....protos.radio import RadioProto
 
 try:
@@ -17,17 +18,18 @@ def __init__(
         logger: Logger,
         radio: RadioProto,
         license: str,
+        message_counter: Counter,
         send_delay: float = 0.2,
     ) -> None:
         """Initialize the packet manager with maximum packet size"""
         self._logger: Logger = logger
         self._radio: RadioProto = radio
         self._send_delay: float = send_delay
         self._license: str = license
-        self._header_size: int = (
-            5  # 2 bytes for sequence number, 2 for total packets, 1 for rssi
-        )
+        # 1 byte for packet identifier, 2 bytes for sequence number, 2 for total packets, 1 for rssi
+        self._header_size: int = 6
         self._payload_size: int = radio.get_max_packet_size() - self._header_size
+        self._message_counter: Counter = message_counter
 
     def send(self, data: bytes) -> bool:
         """Send data"""
@@ -55,8 +57,10 @@ def _pack_data(self, data: bytes) -> list[bytes]:
         """
         Takes input data and returns a list of packets ready for transmission
         Each packet includes:
+        - 1 byte: packet identifier
         - 2 bytes: sequence number (0-based)
         - 2 bytes: total number of packets
+        - 1 byte: rssi
         - remaining bytes: payload
         """
         # Calculate number of packets needed
@@ -67,11 +71,14 @@ def _pack_data(self, data: bytes) -> list[bytes]:
             data_length=len(data),
         )
 
+        packet_identifier: int = self._get_packet_identifier()
+
         packets: list[bytes] = []
         for sequence_number in range(total_packets):
             # Create header
             header: bytes = (
-                sequence_number.to_bytes(2, "big")
+                packet_identifier.to_bytes(1, "big")
+                + sequence_number.to_bytes(2, "big")
                 + total_packets.to_bytes(2, "big")
                 + abs(self._radio.get_rssi()).to_bytes(1, "big")
             )
@@ -117,6 +124,8 @@ def listen(self, timeout: Optional[int] = None) -> bytes | None:
             if packet is None:
                 continue
 
+            packet_identifier, _, total_packets, _ = self._get_header(packet)
+
             # Log received packets
             self._logger.debug(
                 "Received packet",
@@ -125,11 +134,19 @@ def listen(self, timeout: Optional[int] = None) -> bytes | None:
                 payload=self._get_payload(packet),
             )
 
-            # Process received packet
+            if received_packets:
+                (
+                    first_packet_identifier,
+                    _,
+                    _,
+                    _,
+                ) = self._get_header(received_packets[0])
+                if packet_identifier != first_packet_identifier:
+                    continue
+
             received_packets.append(packet)
 
             # Check if we have all packets
-            _, total_packets, _ = self._get_header(packet)
             if total_packets == len(received_packets):
                 self._logger.debug(
                     "Received all expected packets", received=total_packets
@@ -150,19 +167,25 @@ def _unpack_data(self, packets: list[bytes]) -> bytes:
         Returns None if packets are missing or corrupted
         """
         sorted_packets: list = sorted(
-            packets, key=lambda p: int.from_bytes(p[:2], "big")
+            packets, key=lambda p: int.from_bytes(p[1:3], "big")
         )
 
         return b"".join(self._get_payload(packet) for packet in sorted_packets)
 
-    def _get_header(self, packet: bytes) -> tuple[int, int, int]:
+    def _get_header(self, packet: bytes) -> tuple[int, int, int, int]:
         """Returns the sequence number and total packets stored in the header."""
         return (
-            int.from_bytes(packet[0:2], "big"),  # sequence number
-            int.from_bytes(packet[2:4], "big"),  # total packets
-            -int.from_bytes(packet[4:5], "big"),  # RSSI
+            int.from_bytes(packet[0:1], "big"),  # packet identifier
+            int.from_bytes(packet[1:3], "big"),  # sequence number
+            int.from_bytes(packet[3:5], "big"),  # total packets
+            -int.from_bytes(packet[5:6], "big"),  # RSSI
         )
 
     def _get_payload(self, packet: bytes) -> bytes:
         """Returns the payload of the packet."""
         return packet[self._header_size :]
+
+    def _get_packet_identifier(self) -> int:
+        """Increments message_counter and returns the current identifier for a packet"""
+        self._message_counter.increment()
+        return self._message_counter.get()