CRC-CCITT校验算法有关问题

CRC-CCITT校验算法问题
最近用DMR协议其中用到了CRC-CCITT校验算法，协议中关于其描述如下
Consider the n data bits as the coefficients of a polynomial M(x) of degree n-1, associating the MSB of the zero-th octet 
with xn-1 and the LSB of the last octet with x0. Define the generator polynomial, GH(x), and the inversion polynomial, 
IH(x). 
 GH(x) = x16 + x12 + x5 + 1 (B.15) 
 IH(x) = x15 + x14 + x13 + ... + x2 + x + 1 (B.16) 
The CRC polynomial, FH(x), is then computed from the formula: 
 FH(x) = (x16 M(x) mod GH(x)) + IH(x) (B.17) 
modulo 2, i.e. in GF(2). 
The coefficients of FH(x) are placed in the CRC field with the MSB of the zero-th octet of the CRC corresponding to 
x15 and the LSB of the next octet of the CRC corresponding to x0. For the CRC-CCITT calculation the initial remainder 
shall be 000016.

我从网上找了CRC-CCITT的算法程序如下

C/C++ code

void crc16(unsigned char d[], int len){    unsigned char b = 0;    unsigned short crc = 0xffff;    int i, j;    for(i=0; i<len; i++)    {                for(j=0; j<8; j++)        {            b = ((d[i]<<j)&0x80) ^ ((crc&0x8000)>>8);            crc<<=1;            if(b!=0)        crc^=0x1021;        }    }    crc = ~crc;    printf("crc: 0x%.4X ", crc);} 

但是算出了结果不一样，比如一串数据
unsigned char test[10] = {0xb8, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0x00, 0x03, 2b};
我自己算出来crc校验位是0x98CB，但是实际答案是0xDC57，谁帮我看看是不是我找的CRC-CCITT算法有问题？

[解决办法]
google crc, 了解一下，每种的多项式不同，多项式常量不同，不是网上找一个就直接可用的，一般protoclo 中有讲
[解决办法]
CRC16的C语言代码：

typedef unsigned short uint16_t;
typedef unsigned char BYTE;

uint16_t crc16_ccitt(BYTE *ucbuf, int iLen)
{
uint16_t crc = 0xFFFF; // initial value
uint16_t polynomial = 0x1021; // 0001 0000 0010 0001 (0, 5, 12)

for (int j = 0; j < iLen; ++j) {
for (int i = 0; i < 8; i++) {
char bit = ((ucbuf[j] >> (7-i) & 1) == 1);
char c15 = ((crc >> 15 & 1) == 1);
crc <<= 1;
if (c15 ^ bit) crc ^= polynomial;
}
}

crc &= 0xffff;

return crc;
}

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