CRC16

一. CRC16算法

首先在源文件头文件加入表值:

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//////////////////////////////////////////////////////////////////////////

// CRC16码表

static
WORD
const wCRC16Table[256] = {

0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,

0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,

0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,

0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,

0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,

0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,

0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,

0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,

0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,

0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,

0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,

0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,

0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,

0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,

0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,

0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,

0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,

0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,

0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,

0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,

0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,

0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,

0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,

0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,

0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,

0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,

0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,

0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,

0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,

0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,

0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,

0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040};

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//////////////////////////////////////////////////////////////////////////

// 函数功能: CRC16效验

// 输入参数: pDataIn: 数据地址

//           iLenIn: 数据长度

// 输出参数: pCRCOut: 2字节校验值

void CCRCDlg::CRC16(const
CHAR* pDataIn,
int iLenIn,
WORD* pCRCOut)

{
WORD wResult = 0;

WORD wTableNo = 0;

for(int i = 0; i < iLenIn; i++)

{
wTableNo = ((wResult & 0xff) ^ (pDataIn[i] & 0xff));

wResult = ((wResult >> 8) & 0xff) ^ wCRC16Table[wTableNo];

}

*pCRCOut = wResult;
}



//////////////////////////////////////////////////////////////////////////
// 函数功能: CRC16效验
// 输入参数: pDataIn: 数据地址
//           iLenIn: 数据长度
// 输出参数: pCRCOut: 2字节校验值
void CCRCDlg::CRC16(const CHAR* pDataIn, int iLenIn, WORD* pCRCOut)
{
WORD wResult = 0;
WORD wTableNo = 0;

for(int i = 0; i < iLenIn; i++)
{
wTableNo = ((wResult & 0xff) ^ (pDataIn[i] & 0xff));
wResult = ((wResult >> 8) & 0xff) ^ wCRC16Table[wTableNo];
}

*pCRCOut = wResult;
}

二.CRC16(MODBUS)

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//////////////////////////////////////////////////////////////////////////

// CRC MODBUS 效验

// 输入参数: pDataIn: 数据地址

// iLenIn: 数据长度

// 输出参数: pCRCOut: 2字节校验值

void CCRCDlg::CheckCRCModBus(const
CHAR* pDataIn,
int iLenIn,
WORD* pCRCOut)

{
WORD wHi = 0;

WORD wLo = 0;

WORD wCRC;

wCRC = 0xFFFF;

for (int i = 0; i < iLenIn; i++)

{
wCRC = CalcCRCModBus(*pDataIn, wCRC);
pDataIn++;
}

wHi = wCRC / 256;
wLo = wCRC % 256;
wCRC = (wHi << 8) | wLo;

*pCRCOut = wCRC;
}

WORD CCRCDlg::CalcCRCModBus(CHAR cDataIn,
WORD wCRCIn)

{
WORD wCheck = 0;

wCRCIn = wCRCIn ^ cDataIn;

for(int i = 0; i < 8; i++)

{
wCheck = wCRCIn & 1;
wCRCIn = wCRCIn >> 1;
wCRCIn = wCRCIn & 0x7fff;

if(wCheck == 1)

{
wCRCIn = wCRCIn ^ 0xa001;
}
wCRCIn = wCRCIn & 0xffff;
}

return wCRCIn;

}

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//////////////////////////////////////////////////////////////////////////

// 函数功能: CRC16效验(CCITT的0XFFFF效验)

// 输入参数: pDataIn: 数据地址

//           iLenIn: 数据长度

// 输出参数: pCRCOut: 2字节校验值

void CCRCDlg::CRCCCITT(const
CHAR* pDataIn,
int iLenIn,
WORD* pCRCOut)

{
WORD wTemp = 0;

WORD wCRC = 0xffff;

for(int i = 0; i < iLenIn; i++)

{
for(int j = 0; j < 8; j++)

{
wTemp = ((pDataIn[i] << j) & 0x80 ) ^ ((wCRC & 0x8000) >> 8);

wCRC <<= 1;

if(wTemp != 0)

{
wCRC ^= 0x1021;
}
}
}

*pCRCOut = wCRC;
}



//////////////////////////////////////////////////////////////////////////
// 函数功能: CRC16效验(CCITT的0XFFFF效验)
// 输入参数: pDataIn: 数据地址
//           iLenIn: 数据长度
// 输出参数: pCRCOut: 2字节校验值
void CCRCDlg::CRCCCITT(const CHAR* pDataIn, int iLenIn, WORD* pCRCOut)
{
WORD wTemp = 0;
WORD wCRC = 0xffff;

for(int i = 0; i < iLenIn; i++)
{
for(int j = 0; j < 8; j++)
{
wTemp = ((pDataIn[i] << j) & 0x80 ) ^ ((wCRC & 0x8000) >> 8);

wCRC <<= 1;

if(wTemp != 0)
{
wCRC ^= 0x1021;
}
}
}

*pCRCOut = wCRC;
}

//CRC16校验在通讯中应用广泛，这里不对其理论进行讨论，只对常见的3种

//实现方法进行测试。方法1选用了一种常见的查表方法,类似的还有512字

//节、256字等查找表的，至于查找表的生成,这里也略过。

// ---------------- POPULAR POLYNOMIALS ----------------

// CCITT: x^16 + x^12 + x^5 + x^0 (0x1021)

// CRC-16: x^16 + x^15 + x^2 + x^0 (0x8005)

#define CRC_16_POLYNOMIALS 0x8005

// --------------------------------------------------------------

// CRC16计算方法1:使用2个256长度的校验表

// --------------------------------------------------------------

const BYTE chCRCHTalbe[] = // CRC 高位字节值表

{

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,

0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,

0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,

0x00, 0xC1, 0x81, 0x40

};

const BYTE chCRCLTalbe[] = // CRC 低位字节值表

{

0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06, 0x07, 0xC7,

0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD, 0x0F, 0xCF, 0xCE, 0x0E,

0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09, 0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9,

0x1B, 0xDB, 0xDA, 0x1A, 0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC,

0x14, 0xD4, 0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,

0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3, 0xF2, 0x32,

0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4, 0x3C, 0xFC, 0xFD, 0x3D,

0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A, 0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38,

0x28, 0xE8, 0xE9, 0x29, 0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF,

0x2D, 0xED, 0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,

0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60, 0x61, 0xA1,

0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67, 0xA5, 0x65, 0x64, 0xA4,

0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F, 0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB,

0x69, 0xA9, 0xA8, 0x68, 0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA,

0xBE, 0x7E, 0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,

0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 0x70, 0xB0,

0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92, 0x96, 0x56, 0x57, 0x97,

0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C, 0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E,

0x5A, 0x9A, 0x9B, 0x5B, 0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89,

0x4B, 0x8B, 0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,

0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 0x43, 0x83,

0x41, 0x81, 0x80, 0x40

};

WORD CRC16_1(BYTE* pchMsg, WORD wDataLen)

{

BYTE chCRCHi = 0xFF; // 高CRC字节初始化

BYTE chCRCLo = 0xFF; // 低CRC字节初始化

WORD wIndex; // CRC循环中的索引

while (wDataLen--)

{

// 计算CRC

wIndex = chCRCLo ^ *pchMsg++ ;

chCRCLo = chCRCHi ^ chCRCHTalbe[wIndex];

chCRCHi = chCRCLTalbe[wIndex] ;

}

return ((chCRCHi << 8) | chCRCLo) ;

}

// --------------------------------------------------------------

// CRC16计算方法2:使用简单的校验表

// --------------------------------------------------------------

const WORD wCRCTalbeAbs[] =

{

0x0000, 0xCC01, 0xD801, 0x1400, 0xF001, 0x3C00, 0x2800, 0xE401, 0xA001, 0x6C00, 0x7800, 0xB401, 0x5000, 0x9C01, 0x8801, 0x4400,

};

WORD CRC16_2(BYTE* pchMsg, WORD wDataLen)

{

WORD wCRC = 0xFFFF;

WORD i;

BYTE chChar;

for (i = 0; i < wDataLen; i++)

{

chChar = *pchMsg++;

wCRC = wCRCTalbeAbs[(chChar ^ wCRC) & 15] ^ (wCRC >> 4);

wCRC = wCRCTalbeAbs[((chChar >> 4) ^ wCRC) & 15] ^ (wCRC >> 4);

}

return wCRC;

}

// -----------------------------------------------------------------

// CRC16计算方法3:使用直接结算的方法

// -----------------------------------------------------------------

WORD CRC16_3(BYTE* pchMsg, WORD wDataLen)

{

BYTE i, chChar;

WORD wCRC = 0xFFFF;

while (wDataLen--)

{

chChar = *pchMsg++;

chChar = ByteInvert(chChar);

wCRC ^= (((WORD) chChar) << 8);

for (i = 0; i < 8; i++)

{

if (wCRC & 0x8000)

wCRC = (wCRC << 1) ^ CRC_16_POLYNOMIALS;

else

wCRC <<= 1;

}

}

wCRC = WordInvert(wCRC);

return wCRC;

}

//试验数据：

// 采用Metrowerks CodeWarrior在DSP56F80x平台上,对这3种方法

//进行了性能测试。

// ----------------------------------------------------------------

// 代码大小(字) 额外存储空间(字) 执行时间(周期数)

// ----------------------------------------------------------------

// 方法1 32 512 540

// 方法2 57 16 1120

// 方法3 142* 0 4598

//

//说明：方法3的代码大小还包括字反转、字节反转程序(这里没有给出源码)

//

//结论：通常在存储空间没有限制的情况下，采用方法1是最好的，毕竟在

//通讯中，保障通讯速度是至关重要的。而方法2也不失为一种很好的方法，

//占用空间很少。而与方法2相比，方法3似乎不占有什么优势。