#include <stdio.h>

#include <string.h>

//附录 A CRC16校验C程序代码

// #define RUF_MASK 0x 80

//x^16 + 12 5 1

//

#define POLYNOMIAL 0x8408

#define PRESET_VALUE 0xFFFF

#define CHECK_VALUE 0xF0B8

#define CALC_CRC 0x1

#define CHECK_CRC 0x0

unsigned short calc_crc(unsigned char byte_len, unsigned char *data_byte);

//

unsigned short calc_crc(unsigned char byte_len, unsigned char *data_byte)

{

    unsigned short current_crc_value;

    unsigned short i, j;

    current_crc_value = PRESET_VALUE;

    for (i = 0; i < byte_len; i++)

    {

        current_crc_value = current_crc_value ^ data_byte[i];

        for (j = 0; j < 8; j++)

        {

            if (current_crc_value & 0x0001)

            {

                current_crc_value = (current_crc_value >> 1) ^ POLYNOMIAL;

            }

            else

            {

                current_crc_value = (current_crc_value >> 1);

            }

        }

    }

    current_crc_value = ~current_crc_value;

    return (current_crc_value);

}

int main(int argc, char const *argv[])

{

    unsigned short res1 = 0, res2 = 0;

    /* code */

    //0c 7e 55 09 00 00 01 00 16 00 00 78 77

    unsigned char send_buffer[] = {0x09, 0x00, 0x00, 0x01, 0x00, 0x16, 0x00, 0x00};

    //1c 7e 55 19 01 00 00 00 1f 16 00 04 00 04 76 b9 c7 4a 00 00 00 00 00 00 08 00 00 87 f4

    unsigned char recv_buffer[] = {0x19, 0x01, 0x00, 0x00, 0x00, 0x1f, 0x16, 0x00,

                                   0x04, 0x00, 0x04, 0x76, 0xb9, 0xc7, 0x4a, 0x00,

                                   0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00};

    res1 = calc_crc(sizeof(send_buffer), send_buffer);

    res2 = calc_crc(sizeof(recv_buffer), recv_buffer);

    printf("send crc result is msb-->%#2X  lsb-->%#2X\n", res1 / 256, res1 % 256);

    printf("recv crc result is msb-->%#2X  lsb-->%#2X\n", res2 / 256, res2 % 256);

    getchar();

    return 0;

}