Binary coded decimal (BCD) to Hexadecimal conversion

Question

can someone explain to me how to convert BCD to Hexadecimal? For example how can i convert 98(BCD) to Hexadecimal. Thanks.

Answer 1

I don't quite understand your question, but I'm guessing that e.g. someone gives you a number 98 encoded in BCD, which would be:

1001 1000

and you are supposed to get:

62H

What I would propose:

1) convert BCD-encoded value to decimal value (D)

2) convert D to hexadecimal value.

Depending on which programming language you choose, this task will be easier or harder.

EDIT: In Java it could be:

    byte bcd = (byte)0x98; // BCD value: 1001 1000

    int decimal = (bcd & 0xF) + (((int)bcd & 0xF0) >> 4)*10;

    System.out.println(
            Integer.toHexString(decimal)
    );

Answer 2

Go between different combinations of Hex, Decimal, and Binary. If you know how binary works then you should easily be able to use BCD:

Hex  Dec  BCD
0    0    0000
1    1    0001
2    2    0010
3    3    0011
4    4    0100
5    5    0101
6    6    0110
7    7    0111
8    8    1000
9    9    1001
A   10    0001 0000 <-- notice that each digit looks like hex except it can only go to 9.
B   11    0001 0001
C   12    0001 0010
D   13    0001 0011
E   14    0001 0100
F   15    0001 0101

Once you got this part of it down, you should be able to use divide by 10 or %10 to find any combination to generate your BCD. Since it only uses 10 combinations instead of all 16 you will lose some information.

Answer 3

For any BCD encoded value (that will fit in an int).

Iterative:

unsigned int bcd2dec(unsigned int bcd)
{
    unsigned int dec=0;
    unsigned int mult;
    for (mult=1; bcd; bcd=bcd>>4,mult*=10)
    {
        dec += (bcd & 0x0f) * mult;
    }
    return dec;
}

Recursive:

unsigned int bcd2dec_r(unsigned int bcd)
{
    return bcd ? (bcd2dec_r(bcd>>4)*10) + (bcd & 0x0f) : 0; 
}

Answer 4

I'd create a table of 256 entries, mapping all BCD bytes into their binary equivalent; you can then use hex printing of your programming language.

Answer 5

BCD is a subset of hexadecimal, so there is no conversion necessary -- any given BCD value is identical to the corresponding hexadecimal value. For example, '98' in BCD is 10011000, which is the same as 98 in hexadecimal