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   1 /*
   2  * crc.h
   3  *
   4  * Generic CRC calculation code.
   5  *
   6  */
   7
   8 #ifndef CRC_H_
   9 #define CRC_H_
  10
  11 #include <stdint.h>
  12
  13 typedef struct crc {
  14         uint32_t state;
  15         int order;
  16         uint32_t polynom;
  17         uint32_t initial_value;
  18         uint32_t final_xor;
  19         uint32_t mask;
  20 } crc_t;
  21
  22 /* Initialize a crc structure. order is the order of the polynom, e.g. 32 for a CRC-32
  23  * polynom is the CRC polynom. initial_value is the initial value of a clean state.
  24  * final_xor is XORed onto the state before returning it from crc_result(). */
  25 extern void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor);
  26
  27 /* Update the crc state. data is the data of length data_width bits (only the the
  28  * data_width lower-most bits are used).
  29  */
  30 extern void crc_update(crc_t *crc, uint32_t data, int data_width);
  31
  32 /* Clean the crc state, e.g. reset it to initial_value */
  33 extern void crc_clear(crc_t *crc);
  34
  35 /* Get the result of the crc calculation */
  36 extern uint32_t crc_finish(crc_t *crc);
  37
  38 /* Static initialization of a crc structure */
  39 #define CRC_INITIALIZER(_order, _polynom, _initial_value, _final_xor) { \
  40         .state = ((_initial_value) & ((1L<<(_order))-1)), \
  41         .order = (_order), \
  42         .polynom = (_polynom), \
  43         .initial_value = (_initial_value), \
  44         .final_xor = (_final_xor), \
  45         .mask = ((1L<<(_order))-1) }
  46
  47 #endif /* CRC_H_ */