package org.jboss.resteasy.util;

import org.jboss.resteasy.resteasy_jaxrs.i18n.Messages;

public class Hex
{

   
Used building output as Hex
/**
    * Used building output as Hex
    */
   private static final char[] DIGITS = {
           '0', '1', '2', '3', '4', '5', '6', '7',
           '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
   };

   
Converts an array of characters representing hexidecimal values into an
array of bytes of those same values. The returned array will be half the
length of the passed array, as it takes two characters to represent any
given byte. An exception is thrown if the passed char array has an odd
number of elements.
Params:
str – An array of characters containing hexidecimal digits
Throws:
RuntimeException – Thrown if an odd number or illegal of characters
                         is supplied
Returns:
A byte array containing binary data decoded from
        the supplied char array./**
    * Converts an array of characters representing hexidecimal values into an
    * array of bytes of those same values. The returned array will be half the
    * length of the passed array, as it takes two characters to represent any
    * given byte. An exception is thrown if the passed char array has an odd
    * number of elements.
    *
    * @param str An array of characters containing hexidecimal digits
    * @return A byte array containing binary data decoded from
    *         the supplied char array.
    * @throws RuntimeException Thrown if an odd number or illegal of characters
    *                          is supplied
    */
   public static byte[] decodeHex(String str)
   {
      char[] data = str.toCharArray();
      int len = data.length;

      if ((len & 0x01) != 0)
      {
         throw new RuntimeException(Messages.MESSAGES.oddNumberOfCharacters());
      }

      byte[] out = new byte[len >> 1];

      // two characters form the hex value.
      for (int i = 0, j = 0; j < len; i++)
      {
         int f = toDigit(data[j], j) << 4;
         j++;
         f = f | toDigit(data[j], j);
         j++;
         out[i] = (byte) (f & 0xFF);
      }

      return out;
   }

   
Converts a hexadecimal character to an integer.
Params:
ch –    A character to convert to an integer digit
index – The index of the character in the source
Returns:
An integer/**
    * Converts a hexadecimal character to an integer.
    *
    * @param ch    A character to convert to an integer digit
    * @param index The index of the character in the source
    * @return An integer
    */
   protected static int toDigit(char ch, int index)
   {
      int digit = Character.digit(ch, 16);
      if (digit == -1)
      {
         throw new RuntimeException(Messages.MESSAGES.illegalHexadecimalCharacter(ch, index));
      }
      return digit;
   }

   
Converts an array of bytes into an array of characters representing the hexidecimal values of each byte in order.
The returned array will be double the length of the passed array, as it takes two characters to represent any
given byte.
Params:
data – a byte[] to convert to Hex characters
Returns:
A char[] containing hexidecimal characters/**
    * Converts an array of bytes into an array of characters representing the hexidecimal values of each byte in order.
    * The returned array will be double the length of the passed array, as it takes two characters to represent any
    * given byte.
    *
    * @param data a byte[] to convert to Hex characters
    * @return A char[] containing hexidecimal characters
    */
   public static String encodeHex(byte[] data)
   {

      int l = data.length;

      char[] out = new char[l << 1];

      // two characters form the hex value.
      for (int i = 0, j = 0; i < l; i++)
      {
         out[j++] = DIGITS[(0xF0 & data[i]) >>> 4];
         out[j++] = DIGITS[0x0F & data[i]];
      }
      return new String(out);
   }

}