mmu2_crc.h

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#pragma once
#include <stdint.h>
 
namespace modules {
 
// clang-format off
// prevent silly indenting of the whole file
 
namespace crc {
 
class CRC8 {
public:
    static uint8_t CCITT_update(uint8_t crc, uint8_t b);
 
    static constexpr uint8_t CCITT_updateCX(uint8_t crc, uint8_t b) {
        uint8_t data = crc ^ b;
        for (uint8_t i = 0; i < 8; i++) {
            if ((data & 0x80U) != 0) {
                data <<= 1U;
                data ^= 0x07U;
            } else {
                data <<= 1U;
            }
        }
        return data;
    }
 
    static constexpr uint8_t CCITT_updateW(uint8_t crc, uint16_t w) {
        union U {
            uint8_t b[2];
            uint16_t w;
            explicit constexpr inline U(uint16_t w)
                : w(w) {}
        } u(w);
        return CCITT_updateCX(CCITT_updateCX(crc, u.b[0]), u.b[1]);
    }
};
 
} // namespace crc
 
// clang-format on
 
} // namespace modules