import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

/**
 * Utility that dumps out a binary file as hex.
 */
public class Xxd
{
  public static final String PAD = "00000000";
  
  public static String leftPad(String value, int pad)
  {
    if (value.length() < pad)
    {
      if (pad - value.length() > PAD.length())
        throw new IllegalArgumentException("Cannot pad that long");
      return PAD.substring(0, pad - value.length()) + value;
    }
    return value;
  }
  
  public static char printable(int b)
  {
    return (b >= 32 && b < 127) ? (char)b : '.';
      
  }
  
  public static void main(String[] args) throws IOException
  {
    if (args.length < 1)
      System.out.println("Usage: java Xxd {filename}");
    else
    {
      try
      {
        FileInputStream fis = new FileInputStream(args[0]);
        BufferedInputStream bis = new BufferedInputStream(fis);
        int offset = 0;
        byte[] buffer = new byte[16];
        int bytes = bis.read(buffer);
        while (bytes > -1)
        {
          System.out.print(leftPad(Integer.toHexString(offset), 8) + ": ");
          // Print out hex
          for (int i = 0; i < bytes; i++)
            System.out.print(leftPad(Integer.toHexString(buffer[i] & 0xff),
              2) + " ");
          for (int i = 16; i > bytes; i--)
            System.out.print("   ");
          // Print out ASCII
          for (int i = 0; i < bytes; i++)
            System.out.print(printable(buffer[i]));
          System.out.println();
          offset += bytes;
          bytes = bis.read(buffer);
        }
        System.out.println();
      }
      catch (FileNotFoundException fnfe)
      {
        System.out.println("That file does not exist");
      }
    }
  }
}