Convert int to BCD byte array

Question

I want to convert int to byte array [2] using BCD.

The specified object will be obtained from a DateTime representing the Year, and must be converted to two bytes.

Is there any pre-made function that does this, or can you give me an easy way to do this?

Example:

int year = 2010

outputs:

byte[2]{0x20, 0x10};

Answer 1

    static byte[] Year2Bcd(int year) {
        if (year < 0 || year > 9999) throw new ArgumentException();
        int bcd = 0;
        for (int digit = 0; digit < 4; ++digit) {
            int nibble = year % 10;
            bcd |= nibble << (digit * 4);
            year /= 10;
        }
        return new byte[] { (byte)((bcd >> 8) & 0xff), (byte)(bcd & 0xff) };
    }

Beware that you asked for the result with great enthusiasm, which is a bit unusual.

Answer 2

Here is a terrible version of brute force. I'm sure there is a better way than this, but it should work anyway.

int digitOne = year / 1000;
int digitTwo = (year - digitOne * 1000) / 100;
int digitThree = (year - digitOne * 1000 - digitTwo * 100) / 10;
int digitFour = year - digitOne * 1000 - digitTwo * 100 - digitThree * 10;

byte[] bcdYear = new byte[] { digitOne << 4 | digitTwo, digitThree << 4 | digitFour };

, BCD x86, !

Answer 3

Here is a slightly cleaner version than Jeffrey

static byte[] IntToBCD(int input)
{
    if (input > 9999 || input < 0)
        throw new ArgumentOutOfRangeException("input");

    int thousands = input / 1000;
    int hundreds = (input -= thousands * 1000) / 100;
    int tens = (input -= hundreds * 100) / 10;
    int ones = (input -= tens * 10);

    byte[] bcd = new byte[] {
        (byte)(thousands << 4 | hundreds),
        (byte)(tens << 4 | ones)
    };

    return bcd;
}

Answer 4

More common solution

    private IEnumerable<Byte> GetBytes(Decimal value)
    {
        Byte currentByte = 0;
        Boolean odd = true;
        while (value > 0)
        {
            if (odd)
                currentByte = 0;

            Decimal rest = value % 10;
            value = (value-rest)/10;

            currentByte |= (Byte)(odd ? (Byte)rest : (Byte)((Byte)rest << 4));

            if(!odd)
                yield return currentByte;

            odd = !odd;
        }
        if(!odd)
            yield return currentByte;
    }

Answer 5

I did a general procedure published in IntToByteArray that you could use as:

var yearInBytes = ConvertBigIntToBcd (2010, 2);

Answer 6

static byte[] IntToBCD(int input) { 
    byte[] bcd = new byte[] { 
        (byte)(input>> 8), 
        (byte)(input& 0x00FF) 
    };
    return bcd;
}