Initial commit for the firmware. Used the 20090306_ela version as baseline.

[proxmark3-svn] / common / iso14443_crc.c

diff --git a/common/iso14443_crc.c b/common/iso14443_crc.c
new file mode 100644 (file)
index 0000000..cf29d0e
--- /dev/null
+++ b/common/iso14443_crc.c
@@ -0,0 +1,35 @@
+//-----------------------------------------------------------------------------\r
+// Routines to compute the CRCs (two different flavours, just for confusion)\r
+// required for ISO 14443, swiped directly from the spec.\r
+//-----------------------------------------------------------------------------\r
+\r
+#define        CRC_14443_A     0x6363  /* ITU-V.41 */\r
+#define        CRC_14443_B 0xFFFF  /* ISO/IEC 13239 (formerly ISO/IEC 3309) */\r
+\r
+static unsigned short UpdateCrc14443(unsigned char ch, unsigned short *lpwCrc)\r
+{\r
+    ch = (ch ^ (unsigned char) ((*lpwCrc) & 0x00FF));\r
+    ch = (ch ^ (ch << 4));\r
+    *lpwCrc =  (*lpwCrc >> 8) ^ ((unsigned short) ch << 8) ^\r
+               ((unsigned short) ch << 3) ^ ((unsigned short) ch >> 4);\r
+    return (*lpwCrc);\r
+}\r
+\r
+static void ComputeCrc14443(int CrcType, BYTE *Data, int Length,\r
+           BYTE *TransmitFirst, BYTE *TransmitSecond)\r
+{\r
+    unsigned char chBlock;\r
+    unsigned short wCrc=CrcType;\r
+\r
+       do {\r
+        chBlock = *Data++;\r
+        UpdateCrc14443(chBlock, &wCrc);\r
+    } while (--Length);\r
+\r
+    if (CrcType == CRC_14443_B)\r
+        wCrc = ~wCrc;                /* ISO/IEC 13239 (formerly ISO/IEC 3309) */\r
+\r
+    *TransmitFirst = (BYTE) (wCrc & 0xFF);\r
+    *TransmitSecond = (BYTE) ((wCrc >> 8) & 0xFF);\r
+    return;\r
+}\r