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
  15 typedef struct crc {
  16         uint32_t state;
  17         int order;
  18         uint32_t polynom;
  19         uint32_t initial_value;
  20         uint32_t final_xor;
  21         uint32_t mask;
  22 } crc_t;
  23
  24 /* Initialize a crc structure. order is the order of the polynom, e.g. 32 for a CRC-32
  25  * polynom is the CRC polynom. initial_value is the initial value of a clean state.
  26  * final_xor is XORed onto the state before returning it from crc_result(). */
  27 extern void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor);
  28
  29 /* Update the crc state. data is the data of length data_width bits (only the the
  30  * data_width lower-most bits are used).
  31  */
  32 extern void crc_update(crc_t *crc, uint32_t data, int data_width);
  33
  34 /* Clean the crc state, e.g. reset it to initial_value */
  35 extern void crc_clear(crc_t *crc);
  36
  37 /* Get the result of the crc calculation */
  38 extern uint32_t crc_finish(crc_t *crc);
  39
  40 // Calculate CRC-8/Maxim checksum
  41 uint32_t CRC8Maxim(uint8_t *buff, size_t size  );
  42 /* Static initialization of a crc structure */
  43 #define CRC_INITIALIZER(_order, _polynom, _initial_value, _final_xor) { \
  44         .state = ((_initial_value) & ((1L<<(_order))-1)), \
  45         .order = (_order), \
  46         .polynom = (_polynom), \
  47         .initial_value = (_initial_value), \
  48         .final_xor = (_final_xor), \
  49         .mask = ((1L<<(_order))-1) }
  50
  51 #endif /* __CRC_H */