| | 1 | //-----------------------------------------------------------------------------\r |
| | 2 | // Routines to compute the CRCs (two different flavours, just for confusion)\r |
| | 3 | // required for ISO 14443, swiped directly from the spec.\r |
| | 4 | //-----------------------------------------------------------------------------\r |
| | 5 | \r |
| | 6 | #define CRC_14443_A 0x6363 /* ITU-V.41 */\r |
| | 7 | #define CRC_14443_B 0xFFFF /* ISO/IEC 13239 (formerly ISO/IEC 3309) */\r |
| | 8 | \r |
| | 9 | static unsigned short UpdateCrc14443(unsigned char ch, unsigned short *lpwCrc)\r |
| | 10 | {\r |
| | 11 | ch = (ch ^ (unsigned char) ((*lpwCrc) & 0x00FF));\r |
| | 12 | ch = (ch ^ (ch << 4));\r |
| | 13 | *lpwCrc = (*lpwCrc >> 8) ^ ((unsigned short) ch << 8) ^\r |
| | 14 | ((unsigned short) ch << 3) ^ ((unsigned short) ch >> 4);\r |
| | 15 | return (*lpwCrc);\r |
| | 16 | }\r |
| | 17 | \r |
| | 18 | static void ComputeCrc14443(int CrcType, unsigned char *Data, int Length,\r |
| | 19 | unsigned char *TransmitFirst, unsigned char *TransmitSecond)\r |
| | 20 | {\r |
| | 21 | unsigned char chBlock;\r |
| | 22 | unsigned short wCrc=CrcType;\r |
| | 23 | \r |
| | 24 | do {\r |
| | 25 | chBlock = *Data++;\r |
| | 26 | UpdateCrc14443(chBlock, &wCrc);\r |
| | 27 | } while (--Length);\r |
| | 28 | \r |
| | 29 | if (CrcType == CRC_14443_B)\r |
| | 30 | wCrc = ~wCrc; /* ISO/IEC 13239 (formerly ISO/IEC 3309) */\r |
| | 31 | \r |
| | 32 | *TransmitFirst = (unsigned char) (wCrc & 0xFF);\r |
| | 33 | *TransmitSecond = (unsigned char) ((wCrc >> 8) & 0xFF);\r |
| | 34 | return;\r |
| | 35 | }\r |
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