From f1d78c4e7c1675325a58eefbb5be4f20f1f06110 Mon Sep 17 00:00:00 2001
From: iceman1001 <iceman@iuse.se>
Date: Sat, 10 Jun 2023 12:17:56 +0200
Subject: [PATCH] new crc16 option used with Philips toothbrushes.  different
 init value 0x49a3.  Should be reported to the CRC catalog
 https://reveng.sourceforge.io/crc-catalogue/16.htm

---
 common/crc16.c | 23 ++++++++++++++---------
 common/crc16.h |  4 ++++
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/common/crc16.c b/common/crc16.c
index f78fab5b4..d402977b9 100644
--- a/common/crc16.c
+++ b/common/crc16.c
@@ -42,10 +42,14 @@ void init_table(CrcType_t crctype) {
         case CRC_15693:
         case CRC_ICLASS:
         case CRC_CRYPTORF:
+        case CRC_KERMIT:
             generate_table(CRC16_POLY_CCITT, true);
             break;
         case CRC_FELICA:
         case CRC_XMODEM:
+        case CRC_CCITT:
+        case CRC_11784:
+        case CRC_PHILIPS:
             generate_table(CRC16_POLY_CCITT, false);
             break;
         case CRC_LEGIC:
@@ -54,15 +58,6 @@ void init_table(CrcType_t crctype) {
         case CRC_LEGIC_16:
             generate_table(CRC16_POLY_LEGIC_16, true);
             break;
-        case CRC_CCITT:
-            generate_table(CRC16_POLY_CCITT, false);
-            break;
-        case CRC_KERMIT:
-            generate_table(CRC16_POLY_CCITT, true);
-            break;
-        case CRC_11784:
-            generate_table(CRC16_POLY_CCITT, false);
-            break;
         case CRC_NONE:
             crc_table_init = false;
             current_crc_type = CRC_NONE;
@@ -210,6 +205,9 @@ void compute_crc(CrcType_t ct, const uint8_t *d, size_t n, uint8_t *first, uint8
         case CRC_LEGIC_16:
             // TODO
             return;
+        case CRC_PHILIPS:
+            crc = crc16_philips(d, n);
+            break;
         case CRC_NONE:
             return;
     }
@@ -244,6 +242,8 @@ uint16_t Crc16ex(CrcType_t ct, const uint8_t *d, size_t n) {
         case CRC_LEGIC_16:
             // TODO
             return 0;
+        case CRC_PHILIPS:
+            return crc16_philips(d, n);
         case CRC_NONE:
         default:
             break;
@@ -290,6 +290,8 @@ bool check_crc(CrcType_t ct, const uint8_t *d, size_t n) {
         case CRC_LEGIC_16:
             // TODO
             return false;
+        case CRC_PHILIPS:
+            return (crc16_philips(d, n) == 0);
         case CRC_NONE:
         default:
             break;
@@ -350,3 +352,6 @@ uint16_t crc16_legic(uint8_t const *d, size_t n, uint8_t uidcrc) {
     return crc16_fast(d, n, initial, true, false);
 }
 
+uint16_t crc16_philips(uint8_t const *d, size_t n) {
+    return crc16_fast(d, n, 0x49A3, false, false);
+}
\ No newline at end of file
diff --git a/common/crc16.h b/common/crc16.h
index d9631c43c..80758d95b 100644
--- a/common/crc16.h
+++ b/common/crc16.h
@@ -42,6 +42,7 @@ typedef enum {
     CRC_KERMIT,
     CRC_XMODEM,
     CRC_CRYPTORF,
+    CRC_PHILIPS,
 } CrcType_t;
 
 uint16_t update_crc16_ex(uint16_t crc, uint8_t c, uint16_t polynomial);
@@ -78,6 +79,9 @@ uint16_t crc16_iclass(uint8_t const *d, size_t n);
 // ie:  uidcrc = 0x78  then initial_value == 0x7878
 uint16_t crc16_legic(uint8_t const *d, size_t n, uint8_t uidcrc);
 
+// Calculate CRC-16/ Philips.
+uint16_t crc16_philips(uint8_t const *d, size_t n);
+
 // table implementation
 void init_table(CrcType_t crctype);
 void reset_table(void);