1 /*********************************** CRC32 ***********************************/

     2 

     3 /* Use a type crc32_t variable to store the crc value.

     4  * Initialise the variable to CRC32INIT before running the crc routine.

     5  * for more details see the CRC32.C file */

     6 

     7 #ifndef CRC32INIT

     8 #define CRC32INIT 0xFFFFFFFFL /* the initializer for the 32-bit CRC */

     9 

    10 typedef unsigned long crc32_t; /* the type of the 32-bit CRC */

    11 

    12 extern const crc32_t crc32tab[]; /* a table of 32-bit CRC feedback terms */

    13 

    14 #ifdef __cplusplus

    15 

    16 inline crc32_t crc32_update (const crc32_t crc, const unsigned char octet)

    17 {

    18   return crc32tab [(unsigned char) crc ^ octet] ^ ((crc >> 8) & 0x00FFFFFFL);

    19 }

    20 

    21 class crc32_c

    22 {

    23 private:

    24   crc32_t val;

    25 public:

    26   inline crc32_c (const crc32_t v = 0L) : val (v ^ CRC32INIT) {}

    27   inline void init () { val = CRC32INIT; }

    28   inline operator crc32_t () const { return val ^ CRC32INIT; }

    29   inline crc32_t operator = (const crc32_c &n) {

    30     return (val = n.val) ^ CRC32INIT;

    31   }

    32   inline crc32_t operator = (const crc32_t &n) {

    33     return val = n ^ CRC32INIT, n;

    34   }

    35   inline void update (const unsigned char octet) {

    36     val = crc32_update (val, octet);

    37   }

    38   crc32_t update (const unsigned char *block, int len);

    39   inline crc32_t update (const char* block, int len) {

    40     return update((const unsigned char*)block, len);

    41   }

    42 };

    43 #else

    44 #define crc32_update(crc32,octet) ( crc32 = crc32tab[(unsigned char)(crc32) ^ \

    45         (unsigned char)(octet) ] ^ ( ((crc32)>>8) & 0x00FFFFFFL ) )

    46 #endif

    47 

    48 #endif CRC32INIT