C语言版CRC-16系列校验算法_crc16校验-CSDN博客

参考的这篇文章的，基本上是把他的超过来了

CRC（循环冗余校验）在线计算_ip33.com

1. CRC16常见几个标准的算法

RC16常见的标准有以下几种，被用在各个规范中，其算法原理基本一致，就是在数据的输入和输出有所差异，下边把这些标准的差异列出，并给出C语言的算法实现。

　　CRC16_CCITT：多项式x16+x12+x5+1（0x1021），初始值0x0000，低位在前，高位在后，结果与0x0000异或

　　CRC16_CCITT_FALSE：多项式x16+x12+x5+1（0x1021），初始值0xFFFF，低位在后，高位在前，结果与0x0000异或

　　CRC16_XMODEM：多项式x16+x12+x5+1（0x1021），初始值0x0000，低位在后，高位在前，结果与0x0000异或

　　CRC16_X25：多项式x16+x12+x5+1（0x1021），初始值0x0000，低位在前，高位在后，结果与0xFFFF异或

　　CRC16_MODBUS：多项式x16+x15+x5+1（0x8005），初始值0xFFFF，低位在前，高位在后，结果与0x0000异或

　　CRC16_IBM：多项式x16+x15+x5+1（0x8005），初始值0x0000，低位在前，高位在后，结果与0x0000异或

　　CRC16_MAXIM：多项式x16+x15+x5+1（0x8005），初始值0x0000，低位在前，高位在后，结果与0xFFFF异或

　　CRC16_USB：多项式x16+x15+x5+1（0x8005），初始值0xFFFF，低位在前，高位在后，结果与0xFFFF异或

2、CRC16的算法原理及程序

  1. 根据CRC16的标准选择初值CRCIn的值。

  2. 将数据的第一个字节与CRCIn高8位异或。

  3. 判断最高位，若该位为 0 左移一位，若为 1 左移一位再与多项式Hex码异或。

  4. 重复3直至8位全部移位计算结束。

  5. 重复将所有输入数据操作完成以上步骤，所得16位数即16位CRC校验码。

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void InvertUint8(unsigned char *DesBuf, unsigned char *SrcBuf)
{
    int i;
    unsigned char temp = 0;
 
    for(i = 0; i < 8; i++)
    {
        if(SrcBuf[0] & (1 << i))
        {
            temp |= 1<<(7-i);
        }
    }
    DesBuf[0] = temp;
}
void InvertUint16(unsigned short *DesBuf, unsigned short *SrcBuf)
{
    int i;
    unsigned short temp = 0;
 
    for(i = 0; i < 16; i++)
    {
        if(SrcBuf[0] & (1 << i))
        {
            temp |= 1<<(15 - i);
        }
    }
    DesBuf[0] = temp;
}
 
unsigned short CRC16_CCITT(unsigned char *puchMsg, unsigned int usDataLen)
{
    unsigned short wCRCin = 0x0000;
    unsigned short wCPoly = 0x1021;
    unsigned char wChar = 0;
 
    while (usDataLen--)
    {
        wChar = *(puchMsg++);
        InvertUint8(&wChar, &wChar);
        wCRCin ^= (wChar << 8);
 
        for(int i = 0; i < 8; i++)
        {
            if(wCRCin & 0x8000)
            {
                wCRCin = (wCRCin << 1) ^ wCPoly;
            }
            else
            {
                wCRCin = wCRCin << 1;
            }
        }
    }
    InvertUint16(&wCRCin, &wCRCin);
    return (wCRCin) ;
}
 
unsigned short CRC16_CCITT_FALSE(unsigned char *puchMsg, unsigned int usDataLen)
{
    unsigned short wCRCin = 0xFFFF;
    unsigned short wCPoly = 0x1021;
    unsigned char wChar = 0;
 
    while (usDataLen--)
    {
        wChar = *(puchMsg++);
        wCRCin ^= (wChar << 8);
 
        for(int i = 0; i < 8; i++)
        {
            if(wCRCin & 0x8000)
            {
                wCRCin = (wCRCin << 1) ^ wCPoly;
            }
            else
            {
                wCRCin = wCRCin << 1;
            }
        }
    }
    return (wCRCin) ;
}
 
unsigned short CRC16_XMODEM(unsigned char *puchMsg, unsigned int usDataLen)
{
    unsigned short wCRCin = 0x0000;
    unsigned short wCPoly = 0x1021;
    unsigned char wChar = 0;
 
    while (usDataLen--)
    {
        wChar = *(puchMsg++);
        wCRCin ^= (wChar << 8);
 
        for(int i = 0; i < 8; i++)
        {
            if(wCRCin & 0x8000)
            {
                wCRCin = (wCRCin << 1) ^ wCPoly;
            }
            else
            {
                wCRCin = wCRCin << 1;
            }
        }
    }
    return (wCRCin) ;
}
 
unsigned short CRC16_X25(unsigned char *puchMsg, unsigned int usDataLen)
{
    unsigned short wCRCin = 0xFFFF;
    unsigned short wCPoly = 0x1021;
    unsigned char wChar = 0;
 
    while (usDataLen--)
    {
        wChar = *(puchMsg++);
        InvertUint8(&wChar, &wChar);
        wCRCin ^= (wChar << 8);
 
        for(int i = 0;i < 8;i++)
        {
            if(wCRCin & 0x8000)
            {
                wCRCin = (wCRCin << 1) ^ wCPoly;
            }
            else
            {
                wCRCin = wCRCin << 1;
            }
        }
    }
    InvertUint16(&wCRCin, &wCRCin);
    return (wCRCin^0xFFFF) ;
}
 
unsigned short CRC16_MODBUS(unsigned char *puchMsg, unsigned int usDataLen)
{
    unsigned short wCRCin = 0xFFFF;
    unsigned short wCPoly = 0x8005;
    unsigned char wChar = 0;
 
    while (usDataLen--)
    {
        wChar = *(puchMsg++);
        InvertUint8(&wChar, &wChar);
        wCRCin ^= (wChar << 8);
 
        for(int i = 0; i < 8; i++)
        {
            if(wCRCin & 0x8000)
            {
                wCRCin = (wCRCin << 1) ^ wCPoly;
            }
            else
            {
                wCRCin = wCRCin << 1;
            }
        }
    }
    InvertUint16(&wCRCin, &wCRCin);
    return (wCRCin) ;
}
 
unsigned short CRC16_IBM(unsigned char *puchMsg, unsigned int usDataLen)
{
    unsigned short wCRCin = 0x0000;
    unsigned short wCPoly = 0x8005;
    unsigned char wChar = 0;
 
    while (usDataLen--)
    {
        wChar = *(puchMsg++);
        InvertUint8(&wChar, &wChar);
        wCRCin ^= (wChar << 8);
 
        for(int i = 0; i < 8; i++)
        {
            if(wCRCin & 0x8000)
            {
                wCRCin = (wCRCin << 1) ^ wCPoly;
            }
            else
            {
                wCRCin = wCRCin << 1;
            }
        }
    }
    InvertUint16(&wCRCin,&wCRCin);
    return (wCRCin) ;
}
 
unsigned short CRC16_MAXIM(unsigned char *puchMsg, unsigned int usDataLen)
{
    unsigned short wCRCin = 0x0000;
    unsigned short wCPoly = 0x8005;
    unsigned char wChar = 0;
 
    while (usDataLen--)
    {
        wChar = *(puchMsg++);
        InvertUint8(&wChar, &wChar);
        wCRCin ^= (wChar << 8);
 
        for(int i = 0; i < 8; i++)
        {
            if(wCRCin & 0x8000)
            {
                wCRCin = (wCRCin << 1) ^ wCPoly;
            }
            else
            {
                wCRCin = wCRCin << 1;
            }
        }
    }
    InvertUint16(&wCRCin, &wCRCin);
    return (wCRCin^0xFFFF) ;
}
 
unsigned short CRC16_USB(unsigned char *puchMsg, unsigned int usDataLen)
{
    unsigned short wCRCin = 0xFFFF;
    unsigned short wCPoly = 0x8005;
    unsigned char wChar = 0;
 
    while (usDataLen--)
    {
        wChar = *(puchMsg++);
        InvertUint8(&wChar, &wChar);
        wCRCin ^= (wChar << 8);
 
        for(int i = 0; i < 8; i++)
        {
            if(wCRCin & 0x8000)
            {
                wCRCin = (wCRCin << 1) ^ wCPoly;
            }
            else
            {
                wCRCin = wCRCin << 1;
            }
        }
    }
    InvertUint16(&wCRCin, &wCRCin);
    return (wCRCin^0xFFFF) ;
}