crcsum.c

电力系统多功能电表 CRC校验代码源程序大全

// ABB电表密码处理程序，ALPHA协议
unsigned long EncryptionKey(unsigned char *radomkey, unsigned long pword)
{
    int i;                      /*loop index */
    int j,k=0;                  /*used to simulate rotate */

    union {
        unsigned long   key;    /*encryptin key */
        struct{
            unsigned char byta,bytb,bytc,bytd;
        } parts;
    }val;

    val.parts.byta = radomkey[3];
    val.parts.bytb = radomkey[2];
    val.parts.bytc = radomkey[1];
    val.parts.bytd = radomkey[0];

    /* Add an arbitrary number to the key just for fun. */

    val.key += 0xab41;

    /* Generate a four bit checksum to be used as loop index . */

    i = val.parts.byta + val.parts.bytb + val.parts.bytc + val.parts.bytd;
    i = i & 0x0f;

    while ( i>=0) {
        /* Set 'j' to the value of the high bit before shifting. Simulates carry flag. */

        if(val.parts.bytd >=0x80) 
            j = 1;
        else
            j = 0;

        /* Shift the key. Add in the carry flag from the previous loop. */

        val.key = val.key << 1;
        val.key += k;

        k = j;

        /* Apply the key to the password. */

        pword ^= val.key;

        i--;

    } // end of while
    return pword;
}


// 本检验和支持以下电表通讯协议
// IEC1107协议
// DLT645
unsigned char Iec1107CheckSum(unsigned char *buf, unsigned char len)
{
    unsigned char i,c=0;
    for(i=1;i<len;i++)
        c ^=buf[i];
    return c;
}

// 该校验码计算程序支持以下规约
// ModBus规约
// ION规约
// EDMI规约

unsigned int GetCrc16(char *buf, unsigned int len)
{
	int i,flag;
	unsigned int crc = 0;

	while( len--)
	{
		crc ^= ((unsigned int)(*buf++))<<8;
		for(i=0;i<8;i++)
		{
			flag = crc & 0x8000;
			crc <<=1;
			if( flag )
				crc ^= 0x1021;
		}
	}
	return (crc);
}


//CRC校验计算函数
//ION表的ModBus规约

unsigned int GetMbusCrc16(unsigned char *ptr, unsigned int len)  
{   
        unsigned int crc=0xffff;   
        unsigned char i;   
        while(len!=0) 
        {   
            crc^=*ptr; 
            for(i=0;i<8;i++) 
            {   
                if((crc&0x0001)==0) 
                    crc=crc>>1; 
                else  
                { 
                    crc=crc>>1; 
                    crc^=0xa001;  
                }                     
            }
            len-=1; 
            ptr++;  
        }
        return crc; 
}


// 支持以下电表规约
// QUAD4 规约
unsigned int Quad4CRC(unsigned char *buf, unsigned int len)
{
    unsigned int iCRC;
    unsigned char cData;
    unsigned char i,k;
    unsigned int CRC;
    unsigned int XorConst = 0x8005;

    CRC = 0;
    for(k=0;k<len;k++){
        cData=buf[k];
        for (i = 0; i < 8; i++){
            if ((cData & 0x80) != ((CRC >> 8) & 0x80)){
                CRC <<= 1;
                CRC ^= XorConst;
                cData <<= 1;
            }
            else{
                CRC <<= 1;
                cData <<= 1;
            }
        }
    }
    return (CRC);
}