How to program using const uint8_t* const x?

[keryll]

Hi i am going to make a Binary Utility but I don't knnow how to program using

extern uint16_t Bcdbin(const uint8_t* const pBcdBin)

I have already read about extern and about unsigned int but I don't understand how to make a function for that code. please help. ty

[deceptikon]

What do you know about binary coded decimal representation? That appears to be what the function's intended purpose is, which is a bigger issue than the type of pBcdBin.

But the type of pBcdBin is a pointer to zero or more bytes (that's what uin8_t represents here), where neother the pointer itself nor the bytes may be changed, they're both immutable. Technically you could simplify the function signature like so:

short BcdBin(unsigned char *pBcdBin);

This takes advantage of the fact that short int is at least 16 bits and unsigned char is at least 8 bits. The const qualifiers probably aren't necessary, but they make your life easier by enforcing immutability inside the function (ie. stop you from changing them accidentally).

[keryll]

Hi!. the code above is to be used to Convert a two-byte, 3-digit, BCD number into a binary value.
thank you for explaining what the function is, since I was very confused before on how or what their purpose is.
I'm afraid i have to use the above code and can't change it. :(

so a two byte BCD number is the uint16_t? do I have to put arrays to make it to a 3 Digit binary value?