/*
 * ModbusRTUCRC.h
 *
 *      Author: Aleksey Gerasimenko
 *      gerasimenko.aleksey.n@gmail.com
 */

#include <math.h>
#include <stdint.h>


#ifndef MODBUSRTU_MODBUSRTUCRC_H_
#define MODBUSRTU_MODBUSRTUCRC_H_


struct Uint16ByteField
{
    uint16_t low: 8;
    uint16_t high: 8;
};//Uint16ByteField

union Uint16Register
{
    uint16_t all;
    Uint16ByteField byte;
    Uint16Register():
    all(0)
    {}
};//


namespace MODBUSRTU
{

class ModbusRTUCRC
{
private:
    static const uint16_t m_table[256];
private:

    Uint16Register  m_crc_calculate;
    uint16_t        m_table_crc_index;
    Uint16Register  m_table_crc_value;
    uint16_t        *m_start;
    uint16_t        *m_end;
public:
    ModbusRTUCRC();
public:
    uint16_t calculate(uint16_t *start, uint16_t length);
    uint16_t calculate(uint16_t *start, uint16_t *end);
    uint16_t calculate(uint16_t databyte, uint16_t crc);
private:
    inline void _while_cycle();
};

} /* namespace MODBUSRTU */

#endif /* MODBUSRTU_MODBUSRTUCRC_H_ */