#define CRC_16_POLYNOMIALS            0x8005

unsigned short CRC16_3(unsigned char* pchMsg, unsigned short wDataLen) // 1. MSB first; 2. Initial value is 0000;

{

    unsigned char i, chChar;

    unsigned short wCRC = ;

    while (wDataLen--)

    {

        chChar = *pchMsg++;

        wCRC ^= (((unsigned short) chChar) << );

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

        {

            if (wCRC & 0x8000)

                wCRC = (wCRC << ) ^ CRC_16_POLYNOMIALS;

            else

                wCRC <<= ;

        }

    }

    return wCRC;

}