crc校验完整实验c语言实现

下面是一个简单的CRC校验的C语言代码实现：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define CRC8_POLYNOMIAL 0x07
#define CRC16_POLYNOMIAL 0x1021
#define CRC32_POLYNOMIAL 0xEDB88320

unsigned char crc8(unsigned char *data, int len)
{
    unsigned char crc = 0;
    int i, j;
    for (i = 0; i < len; i++) {
        crc ^= data[i];
        for (j = 0; j < 8; j++) {
            if (crc & 0x80) {
                crc = (crc << 1) ^ CRC8_POLYNOMIAL;
            } else {
                crc <<= 1;
            }
        }
    }
    return crc;
}

unsigned short crc16(unsigned char *data, int len)
{
    unsigned short crc = 0;
    int i, j;
    for (i = 0; i < len; i++) {
        crc ^= (data[i] << 8);
        for (j = 0; j < 8; j++) {
            if (crc & 0x8000) {
                crc = (crc << 1) ^ CRC16_POLYNOMIAL;
            } else {
                crc <<= 1;
            }
        }
    }
    return crc;
}

unsigned int crc32(unsigned char *data, int len)
{
    unsigned int crc = 0xFFFFFFFF;
    int i, j;
    for (i = 0; i < len; i++) {
        crc ^= data[i];
        for (j = 0; j < 8; j++) {
            if (crc & 0x80000000) {
                crc = (crc << 1) ^ CRC32_POLYNOMIAL;
            } else {
                crc <<= 1;
            }
        }
    }
    return ~crc;
}

int main()
{
    unsigned char data[] = "hello world";
    unsigned char crc8_val = crc8(data, strlen(data));
    unsigned short crc16_val = crc16(data, strlen(data));
    unsigned int crc32_val = crc32(data, strlen(data));
    printf("CRC8: 0x%x\n", crc8_val);
    printf("CRC16: 0x%x\n", crc16_val);
    printf("CRC32: 0x%x\n", crc32_val);
    return 0;
}

在该代码中，我们定义了三个CRC多项式，分别为8位、16位和32位的CRC校验。然后我们编写了三个函数，分别实现了对应多项式的校验算法。其中，CRC8算法使用了一个8位的查找表，CRC16算法使用了一个16位的查找表，而CRC32算法则直接按照多项式计算。最后在主函数中，我们对字符串"hello world"分别进行了三种CRC校验，并输出了校验结果。