common/crc.h

   1 //-----------------------------------------------------------------------------
   2 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
   3 // at your option, any later version. See the LICENSE.txt file for the text of
   4 // the license.
   5 //-----------------------------------------------------------------------------
   6 // Generic CRC calculation code.
   7 //-----------------------------------------------------------------------------
   8
   9 #ifndef __CRC_H
  10 #define __CRC_H
  11
  12 #include <stdint.h>
  13 #include <stddef.h>
  14 #include <stdbool.h>
  15
  16 typedef struct crc {
  17         uint32_t state;
  18         int order;
  19         uint32_t polynom;
  20         uint32_t initial_value;
  21         uint32_t final_xor;
  22         uint32_t mask;
  23 } crc_t;
  24
  25 /* Initialize a crc structure. order is the order of the polynom, e.g. 32 for a CRC-32
  26  * polynom is the CRC polynom. initial_value is the initial value of a clean state.
  27  * final_xor is XORed onto the state before returning it from crc_result(). */
  28 extern void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor);
  29
  30 /* Update the crc state. data is the data of length data_width bits (only the
  31  * data_width lower-most bits are used).
  32  */
  33 extern void crc_update(crc_t *crc, uint32_t data, int data_width);
  34
  35 /* Clean the crc state, e.g. reset it to initial_value */
  36 extern void crc_clear(crc_t *crc);
  37
  38 /* Get the result of the crc calculation */
  39 extern uint32_t crc_finish(crc_t *crc);
  40
  41 // Calculate CRC-8/Maxim checksum
  42 uint32_t CRC8Maxim(uint8_t *buff, size_t size  );
  43
  44 // Calculate CRC-8 Mifare MAD checksum
  45 uint32_t CRC8Mad(uint8_t *buff, size_t size);
  46
  47 /* Static initialization of a crc structure */
  48 #define CRC_INITIALIZER(_order, _polynom, _initial_value, _final_xor) { \
  49         .state = ((_initial_value) & ((1L<<(_order))-1)), \
  50         .order = (_order), \
  51         .polynom = (_polynom), \
  52         .initial_value = (_initial_value), \
  53         .final_xor = (_final_xor), \
  54         .mask = ((1L<<(_order))-1) }
  55
  56 #endif /* __CRC_H */