From ccdf60d5252080ae05a75e3ab29ce72b7066eac3 Mon Sep 17 00:00:00 2001
From: Pascal Langer <planger@mathworks.com>
Date: Fri, 17 May 2019 17:00:08 +0200
Subject: [PATCH] XN297DUMP: dynamic address search

The dump process is now looking for addresses with different length (3..5) additonnaly to the packet length.
Untested...
---
 Multiprotocol/Multiprotocol.h        |  2 +-
 Multiprotocol/XN297Dump_nrf24l01.ino | 45 +++++++++++++++-------------
 2 files changed, 26 insertions(+), 21 deletions(-)

diff --git a/Multiprotocol/Multiprotocol.h b/Multiprotocol/Multiprotocol.h
index 73bf54d..1969753 100644
--- a/Multiprotocol/Multiprotocol.h
+++ b/Multiprotocol/Multiprotocol.h
@@ -19,7 +19,7 @@
 #define VERSION_MAJOR		1
 #define VERSION_MINOR		2
 #define VERSION_REVISION	1
-#define VERSION_PATCH_LEVEL	47
+#define VERSION_PATCH_LEVEL	48
 
 //******************
 // Protocols
diff --git a/Multiprotocol/XN297Dump_nrf24l01.ino b/Multiprotocol/XN297Dump_nrf24l01.ino
index 59bd4e4..0f60ea8 100644
--- a/Multiprotocol/XN297Dump_nrf24l01.ino
+++ b/Multiprotocol/XN297Dump_nrf24l01.ino
@@ -18,7 +18,6 @@
 #include "iface_nrf24l01.h"
 
 // Parameters which can be modified
-#define XN297DUMP_ADDRESS_LENGTH	5		// Default address length is 5, valid address length is between 3 and 5
 #define XN297DUMP_PERIOD_DUMP		2000	// Multiplied by 50, default 2000=100ms
 #define XN297DUMP_MAX_RF_CHANNEL	84		// Default 84
 
@@ -27,6 +26,8 @@
 #define XN297DUMP_MAX_PACKET_LEN	32
 #define XN297DUMP_CRC_LENGTH		2
 
+uint8_t address_length;
+
 static void __attribute__((unused)) XN297Dump_init()
 {
 	NRF24L01_Initialize();
@@ -41,7 +42,7 @@ static void __attribute__((unused)) XN297Dump_init()
 	NRF24L01_WriteRegisterMulti(NRF24L01_0A_RX_ADDR_P0, (uint8_t*)"\x55\x0F\x71", 3);	// set up RX address to xn297 preamble
 	NRF24L01_WriteReg(NRF24L01_11_RX_PW_P0, XN297DUMP_MAX_PACKET_LEN);	// Enable rx pipe 0
 
-	debug("XN297 dump, scramble=%c, address length=%d, speed=",RX_num?'N':'Y', XN297DUMP_ADDRESS_LENGTH);
+	debug("XN297 dump, scramble=%c, speed=",RX_num?'N':'Y');
 	switch(sub_protocol)
 	{
 		case 0:
@@ -67,17 +68,18 @@ static void __attribute__((unused)) XN297Dump_init()
 
 static boolean __attribute__((unused)) XN297Dump_process_packet(void)
 {
+	uint16_t crcxored;
 	uint8_t packet_ori[XN297DUMP_MAX_PACKET_LEN];
 	memcpy(packet_ori,packet,XN297DUMP_MAX_PACKET_LEN);
-	packet_length=XN297DUMP_MAX_PACKET_LEN-XN297DUMP_CRC_LENGTH;
-
-    while(packet_length > XN297DUMP_ADDRESS_LENGTH)
+	address_length=5;
+	
+    while(address_length >= 3)
 	{
 		// init crc
 		crc = 0xb5d2;
 		
 		// unscramble address
-		for (uint8_t i = 0; i < XN297DUMP_ADDRESS_LENGTH; i++)
+		for (uint8_t i = 0; i < address_length; i++)
 		{
 			crc = crc16_update(crc, packet[i], 8);
 			rx_id[i]=packet[i];
@@ -85,26 +87,29 @@ static boolean __attribute__((unused)) XN297Dump_process_packet(void)
 				rx_id[i] ^= xn297_scramble[i];
 		}
 		// reverse address order
-		for (uint8_t i = 0; i < XN297DUMP_ADDRESS_LENGTH; i++)
-			packet[i]=rx_id[XN297DUMP_ADDRESS_LENGTH-1-i];
+		for (uint8_t i = 0; i < address_length; i++)
+			packet[i]=rx_id[address_length-1-i];
 		
 		// unscramble payload
-		for (uint8_t i = XN297DUMP_ADDRESS_LENGTH; i < packet_length; i++)
+		for (uint8_t i = address_length; i < XN297DUMP_MAX_PACKET_LEN-XN297DUMP_CRC_LENGTH; i++)
 		{
 			crc = crc16_update(crc, packet[i], 8);
 			if (!RX_num)
 				packet[i] ^= xn297_scramble[i];
 			packet[i] = bit_reverse(packet[i]);
+			// check crc
+			if (RX_num)
+				crcxored = crc ^ pgm_read_word(&xn297_crc_xorout[i - 3]);
+			else
+				crcxored = crc ^ pgm_read_word(&xn297_crc_xorout_scrambled[i - 3]);
+			if( (crcxored >> 8) == packet[i + 1] && (crcxored & 0xff) == packet[i + 2])
+			{
+				packet_length=i+1;
+				return true;
+			}
 		}
 
-		// check crc
-		if (RX_num)
-			crc ^= pgm_read_word(&xn297_crc_xorout[packet_length - 3]);
-		else
-			crc ^= pgm_read_word(&xn297_crc_xorout_scrambled[packet_length - 3]);
-		if( (crc >> 8) == packet[packet_length] && (crc & 0xff) == packet[packet_length + 1])
-			return true;
-		packet_length--;
+		address_length--;
 		memcpy(packet,packet_ori,XN297DUMP_MAX_PACKET_LEN);
 	}
 	return false;
@@ -145,12 +150,12 @@ static uint16_t XN297Dump_callback()
 			if(XN297Dump_process_packet())
 			{ // valid crc found
 				debug("A=");
-				for(uint8_t i=0; i<XN297DUMP_ADDRESS_LENGTH; i++)
+				for(uint8_t i=0; i<address_length; i++)
 				{
 					debug(" %02X",packet[i]);
 				}
-				debug(" P(%d)=",packet_length-XN297DUMP_ADDRESS_LENGTH);
-				for(uint8_t i=XN297DUMP_ADDRESS_LENGTH; i<packet_length; i++)
+				debug(" P(%d)=",packet_length-address_length);
+				for(uint8_t i=address_length; i<packet_length; i++)
 				{
 					debug(" %02X",packet[i]);
 				}