请教CRC算法的代码实现！！！

Question

有一个CRC的描述如下，我不知道其代码实现，请各位大虾帮忙！！！！程序执行CRC-CCITT 计算如下：
1. 数据包一次供给CRC 发生器一个字节。在一个新数据包开始时，累加器被
复位，计算使用一个16 位数据寄存器和一个16 位累加器。2. 当一个新的数据字节被收到时，在数据寄存器内的所有位都复位，数据位被
装载进寄存器的高目的位。
<<数据寄存器和累加器之间执行一个异或操作。
<<如果结果的最高标志位是“逻辑0”，累加器的内容将进行逻辑左移，
形成一个新的累加器。
<<如果结果的最高标志位是“逻辑1”，累加器的内容将进行逻辑左移，
与多项式X16＋X12＋X5＋X0 进行一个异或操作，形成一个新的累加器。
<<数据寄存器的内容逻辑左移。3. 此过程字符串的每个字节循环8 次（接收的字节每位一次），最后一个字节
被完全编程后，累加器内的结果就是CRC。4. 如果字节如下的例子：
  （0AH），（03H），（3EH），（44H），（B3H），（BEH），（DCH）和（DDH），
   CRC 为440H，发送的最高标志位是44H

Answer 1

http://www.codeguru.com/Cpp/Cpp/algorithms/checksum/article.php/c5103/

Answer 2

好象是crc16哦void crc_16(BYTE *data, int length, BYTE *reply)
{
 static WORD CRCTABLE[256]={ 0xF078,0xE1F1,0xD36A,0xC2E3,0xB65C,0xA7D5,0x954E,0x84C7,
     0x7C30,0x6DB9,0x5F22,0x4EAB,0x3A14,0x2B9D,0x1906,0x088F,
     0xE0F9,0xF170,0xC3EB,0xD262,0xA6DD,0xB754,0x85CF,0x9446,
     0x6CB1,0x7D38,0x4FA3,0x5E2A,0x2A95,0x3B1C,0x0987,0x180E,
     0xD17A,0xC0F3,0xF268,0xE3E1,0x975E,0x86D7,0xB44C,0xA5C5,
     0x5D32,0x4CBB,0x7E20,0x6FA9,0x1B16,0x0A9F,0x3804,0x298D,
     0xC1FB,0xD072,0xE2E9,0xF360,0x87DF,0x9656,0xA4CD,0xB544,
               0x4DB3,0x5C3A,0x6EA1,0x7F28,0x0B97,0x1A1E,0x2885,0x390C,
     0xB27C,0xA3F5,0x916E,0x80E7,0xF458,0xE5D1,0xD74A,0xC6C3,
     0x3E34,0x2FBD,0x1D26,0x0CAF,0x7810,0x6999,0x5B02,0x4A8B,
     0xA2FD,0xB374,0x81EF,0x9066,0xE4D9,0xF550,0xC7CB,0xD642,
     0x2EB5,0x3F3C,0x0DA7,0x1C2E,0x6891,0x7918,0x4B83,0x5A0A,
     0x937E,0x82F7,0xB06C,0xA1E5,0xD55A,0xC4D3,0xF648,0xE7C1,
     0x1F36,0x0EBF,0x3C24,0x2DAD,0x5912,0x489B,0x7A00,0x6B89,
     0x83FF,0x9276,0xA0ED,0xB164,0xC5DB,0xD452,0xE6C9,0xF740,
     0x0FB7,0x1E3E,0x2CA5,0x3D2C,0x4993,0x581A,0x6A81,0x7B08,
     0x7470,0x65F9,0x5762,0x46EB,0x3254,0x23DD,0x1146,0x00CF,
     0xF838,0xE9B1,0xDB2A,0xCAA3,0xBE1C,0xAF95,0x9D0E,0x8C87,
     0x64F1,0x7578,0x47E3,0x566A,0x22D5,0x335C,0x01C7,0x104E,
     0xE8B9,0xF930,0xCBAB,0xDA22,0xAE9D,0xBF14,0x8D8F,0x9C06,
     0x5572,0x44FB,0x7660,0x67E9,0x1356,0x02DF,0x3044,0x21CD,
     0xD93A,0xC8B3,0xFA28,0xEBA1,0x9F1E,0x8E97,0xBC0C,0xAD85,
     0x45F3,0x547A,0x66E1,0x7768,0x03D7,0x125E,0x20C5,0x314C,
             0xC9BB,0xD832,0xEAA9,0xFB20,0x8F9F,0x9E16,0xAC8D,0xBD04,
     0x3674,0x27FD,0x1566,0x04EF,0x7050,0x61D9,0x5342,0x42CB,
     0xBA3C,0xABB5,0x992E,0x88A7,0xFC18,0xED91,0xDF0A,0xCE83,
      0x26F5,0x377C,0x05E7,0x146E,0x60D1,0x7158,0x43C3,0x524A,
     0xAABD,0xBB34,0x89AF,0x9826,0xEC99,0xFD10,0xCF8B,0xDE02,
     0x1776,0x06FF,0x3464,0x25ED,0x5152,0x40DB,0x7240,0x63C9,
     0x9B3E,0x8AB7,0xB82C,0xA9A5,0xDD1A,0xCC93,0xFE08,0xEF81,
     0x07F7,0x167E,0x24E5,0x356C,0x41D3,0x505A,0x62C1,0x7348,
     0x8BBF,0x9A36,0xA8AD,0xB924,0xCD9B,0xDC12,0xEE89,0xFF00};
    WORD CRCVal,i;
   
    CRCVal=0;
    for(i=0;i<length;i++) CRCVal=CRCTABLE[(CRCVal^=data[i]&0xFF)&0xFF]^(CRCVal>>8);
reply[0]=CRCVal%256;
    reply[1]=CRCVal/256;
}

Answer 3

http://www.codeguru.com/Cpp/Cpp/algorithms/checksum/article.php/c5103/

Answer 4

http://www.codeguru.com/Cpp/Cpp/algorithms/checksum/article.php/c5103/
是CRC32的实现。

Answer 5

WORD Main_CRC16(BYTE Buff[], int nSize)//16位CRC校验
{
WORD m_Crc;
WORD m_InitCrc=0xffff;
unsigned short i,j;
for(i=0;i<nSize;i++)
{
m_InitCrc^=Buff[i];
for(j=0;j<8;j++)
{
m_Crc=m_InitCrc;
m_InitCrc>>=1;
if(m_Crc&0x0001)
m_InitCrc^=0xa001;
}
}
return m_InitCrc;
}可以这样调用：
BYTE m_OutBuff[20];
m_OutBuff[0]=0x01;
m_OutBuff[1]=0x0f;
m_OutBuff[2]=0x00;
m_OutBuff[3]=0x68;
m_OutBuff[4]=0x00;
m_OutBuff[5]=0x03;
m_OutBuff[6]=0x01;
m_OutBuff[7]=0x00;
WORD m_Crc=Main_CRC16(m_OutBuff,8);
lBuffCrc=m_Crc&0x00ff;
hBuffCrc=(m_Crc>>8)&0x00ff;