CRC16常见几个标准的算法及C语言实现

转载： http://blog.csdn.net/leumber/article/details/54311811 CRC16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

模式	多项式	初始值	数据位序	结果处理
CRC16_CCITT	x16+x12+x5+1（0x1021）	0x0000	低位在前，高位在后	与0x0000异或
CRC16_CCITT_FALSE	x16+x12+x5+1（0x1021）	0xFFFF	低位在后，高位在前	与0x0000异或
CRC16_XMODEM	x16+x12+x5+1（0x1021）	0x0000	低位在后，高位在前	与0x0000异或
CRC16_X25	x16+x12+x5+1（0x1021）	0x0000	低位在后，高位在前	与0xFFFF异或
CRC16_ MODBUS	x16+x15+x5+1（0x8005）	0xFFFF	低位在前，高位在后	与0x0000异或
CRC16_ IBM	x16+x15+x5+1（0x8005）	0x0000	低位在前，高位在后	与0x0000异或
CRC16_ MAXIM	x16+x15+x5+1（0x8005）	0x0000	低位在前，高位在后	与0xFFFF异或
CRC16_ USB	x16+x15+x5+1（0x8005）	0xFFFF	低位在前，高位在后	与0xFFFF异或

CRC16的算法原理：

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。
根据算法原理与标准要求就能简单的写出具体程序：

[cpp] view plain copy print?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) ;
}

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) ;
}