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OVERVIEW
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1992-11-06
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THE XPK DATA COMPRESSION PACKAGE
================================
TABLE OF CONTENTS
-----------------
1. What is XPK
2. Installation
3. XPK-Compressors
4. XPK-Applications
5. Usage notes
6. Programming
7. Contact addresses
8. Legal issues
1. What is XPK
--------------
For a long time, there have been various compression programs for different
purposes on the Amiga. But every application supported only one compressor,
and most compressors were only supported by one application. XPK wants to
put an end to this: Every application with XPK interface can use very packer
with XPK interface. An XPK packer is a library with a four letter library
name.
2. Installation
---------------
You can either double-click the 'Install' icon in the distribution, or you
cd to the directory where you unpacked XPK and type
copy libs libs: ALL
For installing the various applications, refer to their documentation.
3. XPK-Compressors
------------------
First a general overview of the most important packers and crypters and
their uses.
- NUKE is currently the best compressor for files that are compressed once
and decompressed many times, since it has a reasonable compression factor
at an excellent decompression speed. Typical applications: On-disk and
on-harddisk compression of data, e.g. for XFH.
- BLZW compresses very quickly and thus can be used for data that are
compressed at least as often as decompressed. Probably the most suitable
packer for backup systems, unless you have a fast CPU and a slow backup
medium.
- FEAL encrypts data at reasonable speed with very high safety, ie. it has
not yet been broken in the higher-round modes. Any kind of private data
is safe in the hands of FEAL.
Now for the complete overview of all existing compressors. You may not have
all of them. The meaning of the fields:
Name: 4 letter name of the packer.
CSpd: Compression speed in K/sec on an A3000
USpd: Decompression speed in K/sec on an A3000
CF : Compression factor in %
Mo : This packer supports modes
Cry : This packer can encrypt
Desc: Description of the packer
Name CSpd USpd CF Mo Cry Desc
---- ---- ---- -- -- --- ----
BLZW 139 364 32 + - Fast compression & decompression, usable CF
CBR0 410 1918 3 - - Byte run encoding, only for simple files (Gfx)
DLTA 104 1265 - - - Pre-processor for packing of sound samples
ENCO 393 393 - - + Sample library for cryptors
FEAL 109 109 - + + Encryption with selectable safety
HUFF 88 138 24 - - Huffman coding, low CF and speed
IDEA 90 90 - + + Safe Encryption, not too fast, many variations
IMPL 6 280 44 + - Imploder, good CF, slow compression, fast decomp
NONE 1918 2477 0 - - Do-nothing packer
NUKE 36 630 45 - - Very fast decompression, good CF & fast compression
RLEN 170 1351 4 - - Sample library for packers
SHRI 5 9 52 + - Excellent CF but low speed
VERN 861 874 - - + Less safe but very fast Vernam encryption
---- ---- ---- -- -- --- ----
Also, XPK supports powerpacker.library for decompression.
4. XPK-Applications
-------------------
These is a complete list of the XPK applications known to me.
XFH (De)compressing filesystem
xDrop File (un)packer for OS 2.0 with intuition interface
xPack File (un)packer with OS 2.0 style shell interface
xPK File (un)packer with UNIX style shell interface
xUP File unpacker with UNIX style shell interface
xDir Shows files and their packing status
xQuery Shows available packers and their properties
xLoadSeg Allows loading of XPK-packed executables
Most Text displayer with mouse support for OS 2.1
MultiPlayer Universal module player with XPK decompression
MoisePlayer Universal module player with XPK decompression
DeliTracker Universal module player with XPK decompression
ShowIFF IFF image displayer with XPK decompression in iff.library
AShow IFF image displayer with XPK decompression in iff.library
MoviePro Movie/Anim 5 player with XPK decompression in iff.library
GL Anim player for .gl format
Kwikbackup Harddisk to diskette backup system
5. Usage notes
--------------
XPK has been created to save space on your disks, less for file compression
in order to transmit them. The idea behind XPK is you compress your files
and keep using them as if they were uncompressed. On harddisk, you can use
XFH to compress any kind of data since the application doesn't notice they
are compressed. On diskette, you only can compress the types of data that
a decompressing application exists for, like IFF pictures and ShowIFF.
Please note that compression is always a risk. There is a possibility
for errors in the compression algorithm, and if one single bit is
corrupted in a compressed file, the whole file is lost. Thus, do not
compress vital data like program source codes or private letters; we do
not take any responsibility for lost data. Please report bugs to the
respective author immediately; you might keep other from loosing data.
6. Programming
--------------
XPK has a very easy-to-use interface for application and compressor
programmers. Support files exist for SAS, DICE, GCC and Aztec C,
most assemblers, Modula and Oberon. There is a developer package,
xpkXX.lha (where XX is the version number, e.g. 25 for 2.5) which
can be found on Aminet. Aminet is a number of FTP sites that share
files. Main site is amiga.physik.unizh.ch (130.60.80.80) where XPK
can be found in pub/aminet/util/pack.
7. Contact addresses
--------------------
Almost all XPK authors have an e-mail address. I list the most important
ones here; check the application/packer documentation if you don't find
someone here.
Urban Dominik Mueller umueller@amiga.physik.unizh.ch XPK, NUKE
Bryan Ford bryanf@hpmcaa.mcm.hp.com XPK, BLZW
Peter Struijk winfjmf@dutiws.TWI.TUDelft.NL IMPL
Christian von Roques roques@karlsruhe.gmd.de FEAL
Andre Beck beck@freia.inf.tu-dresden.de IDEA
Marc Zimmermann zimmerma@ibr.cs.tu-bs.de HUFF
Kristian Nielsen bombadil@diku.dk XFH
Martin A. Blatter blatter@amiga.physik.unizh.ch xDrop
Matthias Scheler tron@uni-paderborn.de xPack
8. Legal issues
---------------
This package may be freely distributed, as long as it is kept in its
original, complete, and unmodified form. It may not be distributed by
itself or in a commercial package of any kind without my permission.
These programs are distributed in the hope that they will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.
-Urban Dominik Mueller umueller@amiga.physik.unizh.ch