CHG: extracted a #define for the crc16 poly

[proxmark3-svn] / common / iso15693tools.c

diff --git a/common/iso15693tools.c b/common/iso15693tools.c
index 6d8ae5b135c9c7390359741ae84666cb0de8eb99..26e636ca7b0c27d90dee14bf3f79d70168fd546c 100644 (file)
--- a/common/iso15693tools.c
+++ b/common/iso15693tools.c
@@ -12,6 +12,9 @@
 #include <stdlib.h>
 //#include "iso15693tools.h"
 
+#define POLY 0x8408
+
+
 // The CRC as described in ISO 15693-Part 3-Annex C
 //     v       buffer with data
 //             n       length
@@ -56,12 +59,38 @@ int sprintf(char *str, const char *format, ...);
 //             uid[]           the UID in transmission order
 //     return: ptr to string
 char* Iso15693sprintUID(char *target,uint8_t *uid) {
-  static char tempbuf[9]="";
+  static char tempbuf[2*8+1]="";
   if (target==NULL) target=tempbuf;
-  sprintf(target,"%02hX%02hX%02hX%02hX%02hX%02hX%02hX%02hX",
+  sprintf(target,"%02X%02X%02X%02X%02X%02X%02X%02X",
                                uid[7],uid[6],uid[5],uid[4],uid[3],uid[2],uid[1],uid[0]);
   return target;
 }
 
+uint16_t iclass_crc16(char *data_p, unsigned short length)
+{
+      unsigned char i;
+      unsigned int data;
+         uint16_t crc = 0xffff;
+
+      if (length == 0)
+            return (~crc);
+
+      do
+      {
+            for (i=0, data=(unsigned int)0xff & *data_p++;
+                 i < 8; 
+                 i++, data >>= 1)
+            {
+                  if ((crc & 0x0001) ^ (data & 0x0001))
+                        crc = (crc >> 1) ^ POLY;
+                  else  crc >>= 1;
+            }
+      } while (--length);
 
+      crc = ~crc;
+      data = crc;
+      crc = (crc << 8) | (data >> 8 & 0xff);
+      crc = crc ^ 0xBC3;
+      return (crc);
+}