c++ 实现CRC-16 校验

以下是C++实现CRC-16校验的示例代码：

#include <iostream>

using namespace std;

unsigned short crc16(unsigned char *data, unsigned int length, unsigned short crc)
{
    const unsigned short polynomial = 0x1021;
    unsigned short crc_register = crc;

    for (unsigned int i = 0; i < length; i++)
    {
        for (unsigned char bit = 0x80; bit > 0; bit >>= 1)
        {
            bool c15 = crc_register & 0x8000;
            bool bit_in = data[i] & bit;
            crc_register <<= 1;
            if (bit_in != 0)
                crc_register |= 0x0001;
            if (c15 != 0)
                crc_register ^= polynomial;
        }
    }

    return crc_register;
}

int main()
{
    unsigned char data[] = {0x01, 0x02, 0x03, 0x04};
    unsigned int length = sizeof(data);
    unsigned short crc = 0x0000;

    unsigned short crc_result = crc16(data, length, crc);

    cout << "CRC-16校验结果为：" << hex << crc_result << endl;

    return 0;
}

其中，crc16函数接受三个参数：待校验数据的指针，数据长度和初始CRC值。在函数内部，我们使用了CRC-16的标准生成多项式0x1021进行计算，最后返回计算出的CRC校验值。在main函数中，我们将待校验数据赋值给data数组，调用crc16函数计算CRC-16校验值，并输出结果。