crc8hondak.cpp

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#include <stddef.h>
#include <stdint.h>
 
#include "crc8hondak.h"
 
static inline uint8_t crc_init(void)
{
    return 0xff;
}
 
static inline uint8_t crc_next(uint8_t crc, uint8_t data)
{
    uint8_t eor;
    unsigned int i = 8;
 
    crc ^= data;
    do {
        /* This might produce branchless code */
        eor = crc & 1 ? 0xb8 : 0;
        crc >>= 1;
        crc ^= eor;
    } while (--i);
 
    return crc;
}
 
static inline uint8_t crc_final(uint8_t crc) {
    return ~crc;
}
 
uint8_t crc_hondak_calc(const uint8_t *data, size_t len) {
    uint8_t crc = crc_init();
 
    if (len) do {
        crc = crc_next(crc, *data++);
    } while (--len);
 
    return crc_final(crc);
}