content: /**
   * Copyright (C) 2014-2016 Open Whisper Systems
   *
   * Licensed according to the LICENSE file in this repository.
   */
  package org.whispersystems.libsignal.util;
  
  import java.io.IOException;
  
  /**
   * Utility for generating hex dumps.
   */
  public class Hex {
  
    private final static char[] HEX_DIGITS = {
      '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
    };
  
    public static String toString(byte[] bytes) {
      return toString(bytes, 0, bytes.length);
    }
  
    public static String toString(byte[] bytes, int offset, int length) {
      StringBuffer buf = new StringBuffer();
      for (int i = 0; i < length; i++) {
        appendHexChar(buf, bytes[offset + i]);
        buf.append(", ");
      }
      return buf.toString();
    }
  
    public static String toStringCondensed(byte[] bytes) {
      StringBuffer buf = new StringBuffer();
      for (int i=0;i<bytes.length;i++) {
        appendHexChar(buf, bytes[i]);
      }
      return buf.toString();
    }
  
    public static byte[] fromStringCondensed(String encoded) throws IOException {
      final char[] data = encoded.toCharArray();
      final int    len  = data.length;
  
      if ((len & 0x01) != 0) {
        throw new IOException("Odd number of characters.");
      }
  
      final byte[] out = new byte[len >> 1];
  
      for (int i = 0, j = 0; j < len; i++) {
        int f = Character.digit(data[j], 16) << 4;
        j++;
        f = f | Character.digit(data[j], 16);
        j++;
        out[i] = (byte) (f & 0xFF);
      }
  
      return out;
    }
  
    private static void appendHexChar(StringBuffer buf, int b) {
      buf.append("(byte)0x");
      buf.append(HEX_DIGITS[(b >> 4) & 0xf]);
      buf.append(HEX_DIGITS[b & 0xf]);
    }
  
  }
  