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Joined: 23 Aug 2005
Posts: 93
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| Calculating BCC? |
 Posted: Thu Jan 19, 2006 8:24 am |
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Hi, can someone help me to do a "driver" to calculate the BCC of a string of chars, bytes? from a printf function.
I know BCC is the xor of all the chars in a string,but...
Is there any ready function for this in CCS?
Something like this?
| Code: |
char bcc_calc(void){
char bcc=0;
char const* p=string1;
while(*p)
bcc^=*p++;
return bcc;
}
void func(char bcc){
printf("%s",string1)
putc(bcc_calc());
}
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Ttelmah
Guest
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| Posted: Thu Jan 19, 2006 9:31 am |
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There is not an inbuilt function, but you can take advantage of the ability of printf, to 'print' to another function.
So:
| Code: |
int8 bcc;
#define RESET_BCC bcc=0
void putcsum(int8 val) {
bcc^=val;
putc(val);
}
//Then in your main code:
RESET_BCC;
printf(putcsum,string);
putc(bcc);
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What happens here, is that you set the 'bcc' value to zero (RESET_BCC), then printf the characters, to the routine 'putcsum', which actually outputs them, and xors them into bcc.
You then just send the checksum.
The big advantage, is that the code only has to access the array once for each character. Array accesses are slow.
Best Wishes |
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