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[DDC]

I am trying to implement the algorithm of a CRC check, which basically created a value, based on an input message.
So, consider I have a hex message 3F214365876616AB15387D5D59, and I want to obtain the CRC24Q value of the message.
The algorithm that I found to do this is the following:

    typedef     unsigned long crc24;

    crc24 crc_check(unsigned char *input) {

        	unsigned char *octets; 

        	crc24 crc = 0xb704ce; // CRC24_INIT;

        	int i;

        	int len = strlen(input); 

    	octets = input;

    

    	while (len--) {

    		crc ^= ((*octets++) << 16); 

    	    

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

    			crc <<= 1; 

    			if (crc & 0x1000000) 

    				crc ^= CRC24_POLY;

    		}

    	}

    	return crc & 0xFFFFFF;

    }

where *input=3F214365876616AB15387D5D59.
The problem is that ((*octets++) << 16) will shift by 16 bits the ascii value of the hex character and not the character itself.
So, I made a function to convert the hex numbers to characters.
I know the implementation looks weird, and I wouldn't be surprised if it were wrong.
This is the convert function:

char* convert(unsigned char* message) {

    	unsigned char* input;

    	input = message;

    	int p;

    

    	char *xxxx[20];

    	xxxx[0]="";

    

    	for (p = 0; p < length(message) - 1; p = p + 2) {

    		char* pp[20];

    		pp[0] = input[0];

    		char *c[20];

    		*input++;

    		c[0]= input[0];

    		*input++;

    		strcat(pp,c);

    		char cc;

    		char tt[2];

    		cc = (char ) strtol(pp, &pp, 16);

    		tt[0]=cc;

    		strcat(xxxx,tt);

    

    	}

    	return xxxx;

    }

SO:

  unsigned char *msg_hex="3F214365876616AB15387D5D59";

    crc_sum = crc_check(convert((msg_hex)));

    printf("CRC-sum: %x\n", crc_sum);

The correct result is 0xBA0568
Thank you very much for any suggestions.