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[proxmark3-svn] / common / iso14443crc.c

#include "iso14443crc.h"\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
void ComputeCrc14443(int CrcType,\r
                     unsigned char *Data, int Length,\r
                     unsigned char *TransmitFirst,\r
                     unsigned char *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 = (unsigned char) (wCrc & 0xFF);\r
    *TransmitSecond = (unsigned char) ((wCrc >> 8) & 0xFF);\r
    return;\r
}\r