X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/b811cc51f9a21324dc7589d1254e767374488a20..6658905f18a1eebc148836f26c731dea9c1377dc:/common/iso14443_crc.c

diff --git a/common/iso14443_crc.c b/common/iso14443_crc.c
new file mode 100644
index 00000000..cf29d0e0
--- /dev/null
+++ b/common/iso14443_crc.c
@@ -0,0 +1,35 @@
+//-----------------------------------------------------------------------------
+// Routines to compute the CRCs (two different flavours, just for confusion)
+// required for ISO 14443, swiped directly from the spec.
+//-----------------------------------------------------------------------------
+
+#define	CRC_14443_A	0x6363	/* ITU-V.41 */
+#define	CRC_14443_B 0xFFFF  /* ISO/IEC 13239 (formerly ISO/IEC 3309) */
+
+static unsigned short UpdateCrc14443(unsigned char ch, unsigned short *lpwCrc)
+{
+    ch = (ch ^ (unsigned char) ((*lpwCrc) & 0x00FF));
+    ch = (ch ^ (ch << 4));
+    *lpwCrc =	(*lpwCrc >> 8) ^ ((unsigned short) ch << 8) ^
+            	((unsigned short) ch << 3) ^ ((unsigned short) ch >> 4);
+    return (*lpwCrc);
+}
+
+static void ComputeCrc14443(int CrcType, BYTE *Data, int Length,
+           BYTE *TransmitFirst, BYTE *TransmitSecond)
+{
+    unsigned char chBlock;
+    unsigned short wCrc=CrcType;
+
+	do {
+        chBlock = *Data++;
+        UpdateCrc14443(chBlock, &wCrc);
+    } while (--Length);
+
+    if (CrcType == CRC_14443_B)
+        wCrc = ~wCrc;                /* ISO/IEC 13239 (formerly ISO/IEC 3309) */
+
+    *TransmitFirst = (BYTE) (wCrc & 0xFF);
+    *TransmitSecond = (BYTE) ((wCrc >> 8) & 0xFF);
+    return;
+}