pack.java

jzss压缩算法

/*         ______   ___    ___ 
 *        /\  _  \ /\_ \  /\_ \ 
 *        \ \ \L\ \\//\ \ \//\ \      __     __   _ __   ___ 
 *         \ \  __ \ \ \ \  \ \ \   /'__`\ /'_ `\/\`'__\/ __`\
 *          \ \ \/\ \ \_\ \_ \_\ \_/\  __//\ \L\ \ \ \//\ \L\ \
 *           \ \_\ \_\/\____\/\____\ \____\ \____ \ \_\\ \____/
 *            \/_/\/_/\/____/\/____/\/____/\/___L\ \/_/ \/___/
 *                                           /\____/
 *                                           \_/__/
 *
 *      LZSS File compression utility for the Allegro library.
 *
 *      By Shawn Hargreaves.  
 *
 *      Java version by Radim Kolar.
 *
 */
 
import java.io.*;

public class pack
{

public final static byte F_PACK_MAGIC[]={ 0x73,0x6C,0x68,0x21};
/* magic number for packed files */
public final static byte F_NOPACK_MAGIC[]= { 0x73, 0x6C, 0x68, 0x2E};
/* magic number for autodetect */

private static void usage()
{
   System.out.print("\nFile compression utility for Allegro 3.12");
   System.out.print("\nBy Shawn Hargreaves, Aug 1999. Java version by Radim Kolar, Dec 1999\n\n");
   System.out.print("Usage: 'pack <in> <out>' to pack a file\n");
   System.out.print("       'pack u <in> <out>' to unpack a file\n");

   System.exit(1);
}

public static void main(String argv[]) throws IOException
{
   String t="";
   String f1="",f2="";
   InputStream in;
   OutputStream out;
   long s1,s2;
   boolean pack=true;
   
   if (argv.length==2) {
      f1 = argv[0];
      f2 = argv[1];
      t = "Pack";
   }
   
   else if ((argv.length==3) && (argv[0].length()==1) &&
	    ((argv[0].charAt(0)=='u') || (argv[0].charAt(0)=='U'))) {
      f1 = argv[1];
      f2 = argv[2];
      t = "Unpack";
      pack=false;
   }
   
   else
      usage();

   if (f1.equals(f2))
    {
	   System.out.println("\nError: Files must be different.");
	   System.exit(1);
    }
   in = null;
   try
     {
       in  = new FileInputStream(f1);
     }
   catch ( IOException i)
     {
	   System.out.println("\nError: "+f1+" - Can't open.");
	   System.exit(1);
     }
   s1 = new File(f1).length();

   /* handle magic */
   if(!pack)           {
	    byte magic[]=new byte[4];
	    in.read(magic);
	    int bad=0;
	    for(int i=2;i>=0;i--)
	     if(magic[i]!=F_PACK_MAGIC[i]) 
	         bad=1;
            if(bad==0)
	      if(magic[3]!=F_PACK_MAGIC[3])
	        if(magic[3]==F_NOPACK_MAGIC[3]) bad=2;
		   else                         bad=1;
            if(bad==1)
	      {
	         System.out.println("\nError: "+f1+" - Not a packed file. (No magic)");
		 System.exit(1);
	      }
	    if(bad==0) in  = new LZSSInputStream(in);
   }
   
   out = new FileOutputStream(f2);
   
   if(pack) 
            {
              out.write(F_PACK_MAGIC);
	      out = new LZSSOutputStream(out);
	    }

   System.out.println(t+"ing "+f1+" into "+f2+"...");

   byte b[]=new byte[512];
   int i;
   while ( (i=in.read(b))!=-1) {
      out.write(b,0,i);
   }

   in.close();
   out.close();

   if (s1 > 0) {
      s2 = new File(f2).length();
      System.out.println("\nInput size: "+s1+"\nOutput size: "+s2+"\n"+(s2*100+(s1>>1))/s1+"%");
   }

   return;
}
}