findLastPacket

        fn findLastPacket(data: *const Data, buffer: *const [max_packet_len]u8) struct { u16, u16 } {
            assert(data.state == .ready);
            var packet_start: u16 = 0;
            var packet_end: u16 = 0;
            const bytes_read = data.bytes_read;
            while (bytes_read - packet_end >= 1) {
                const nodes_len: u16 = buffer[packet_end];
                const packet_len = 1 + nodes_len * (@sizeOf(Node.Storage) + @sizeOf(Node.Parent));
                if (packet_end + packet_len > bytes_read) break;
                packet_start = packet_end;
                packet_end += packet_len;
            }
            return .{ packet_start, packet_end };
        }