updater/crccheck.c

   1 /****************************************************************************/
   2 /* CRC32 stuff taken and adapted from lib_crc version 1.16 :                */
   3 /*   Library         : lib_crc                                              */
   4 /*   File            : lib_crc.c                                            */
   5 /*   Author          : Lammert Bies  1999-2008                              */
   6 /*   E-mail          : info@lammertbies.nl                                  */
   7 /****************************************************************************/
   8
   9 /* the ATxmega series NVM CRC compatible polynom */
  10 /* on ATxmega you can do this much faster in hardware */
  11 #define                 P_32        0xEDB88320L
  12 #define                 D_32        0xFFFFFFFFL
  13
  14 uint32_t crc_tab32_value(uint8_t address) {
  15   uint32_t result;
  16   uint8_t  j;
  17
  18   result = (uint32_t)address & 0xffL;
  19   for (j=0; j<8; j++) {
  20       if (result & 0x00000001L) result = (result >> 1) ^ P_32;
  21       else                      result = result >> 1;
  22   }
  23
  24   return result;
  25 }
  26
  27 uint32_t update_crc_32(uint32_t crc, uint8_t c) {
  28   uint32_t tmp, long_c;
  29
  30   long_c = (uint32_t)c & 0xffL;
  31
  32   tmp = crc ^ long_c;
  33   crc = (crc >> 8) ^ crc_tab32_value(tmp & 0xffL);
  34
  35   return crc;
  36 }