code: static int decodeDigit(byte data)
  	{
  		char charData = (char) data;
  		if (charData <= 'Z' && charData >= 'A')
  		{
  			return charData - 'A';
  		}
  		if (charData <= 'z' && charData >= 'a')
  		{
  			return charData - 'a' + 26;
  		}
  		if (charData <= '9' && charData >= '0')
  		{
  			return charData - '0' + 52;
  		}
  		switch (charData)
  		{
  			case '+':
  				return 62;
  			case '/':
  				return 63;
  			default:
  				throw new IllegalArgumentException("Invalid char to decode: " + data); //$NON-NLS-1$
  		}
  	}
docs: This method converts a Base 64 digit to its numeric value.
  
  @param data
  digit (character) to convert
  @return value for the digit