From 1d5464397c4a6e0c251ba7ed80f4f797a9063cb0 Mon Sep 17 00:00:00 2001
From: iceman1001 <iceman@iuse.se>
Date: Tue, 16 Feb 2016 10:44:12 +0100
Subject: [PATCH] ADD: first try to implement crc-16 for Legic Advant *not
 working yet*  Can't verify it.

---
 common/crc16.c | 8 ++++++++
 common/crc16.h | 1 +
 2 files changed, 9 insertions(+)

diff --git a/common/crc16.c b/common/crc16.c
index c90eeb55..9d3f68c9 100644
--- a/common/crc16.c
+++ b/common/crc16.c
@@ -9,6 +9,7 @@
 #include "crc16.h"
 #define CRC16_POLY_CCITT 0x1021
 #define CRC16_POLY 0x8408
+#define CRC16_POLY_LEGIC 0xB400
 
 unsigned short update_crc16( unsigned short crc, unsigned char c )
 {
@@ -48,6 +49,13 @@ uint16_t crc16_ccitt(uint8_t const *message, int length) {
 uint16_t crc16_ccitt_kermit(uint8_t const *message, int length) {
     return bit_reverse_uint16(crc16(message, length, 0x0000, CRC16_POLY_CCITT));
 }
+
+//ICEMAN: not working yet,
+// This CRC-16 is used in Legic Advant systems. 
+uint16_t crc16_legic(uint8_t const *message, int length, uint16_t inital) {
+	return crc16(message, length, inital, CRC16_POLY_LEGIC);
+}
+
 uint16_t bit_reverse_uint16 (uint16_t value) {
 	const uint16_t mask0 = 0x5555;
 	const uint16_t mask1 = 0x3333;
diff --git a/common/crc16.h b/common/crc16.h
index 8eb4befb..d53c7766 100644
--- a/common/crc16.h
+++ b/common/crc16.h
@@ -13,5 +13,6 @@ unsigned short update_crc16(unsigned short crc, unsigned char c);
 uint16_t crc16(uint8_t const *message, int length, uint16_t remainder, uint16_t polynomial);
 uint16_t crc16_ccitt(uint8_t const *message, int length);
 uint16_t crc16_ccitt_kermit(uint8_t const *message, int length);
+uint16_t crc16_legic(uint8_t const *message, int length, uint16_t inital);
 uint16_t bit_reverse_uint16 (uint16_t value);
 #endif
-- 
2.39.2