Author    markn@tiny.com (Mark Nelson)
Uploader: osterh00@marvin.informatik.uni-dortmund.de (Andre Osterhues)
Type:     util/pack
Requires: ixemul v40.2

This is the Amiga port of the Burrows-Wheler Transform.
It makes a given input file more compressible by sorting the input in a
specific order. Combined with good compressors, it gives ratios mostly
superior to GZIP/PKZIP.

A Run Length Encoder, an Arithmetic Coder and a Move-To-Front Coder are also
included to form a powerful compression package.

A paper on the transform by Mark Nelson, the author, is to appear in Dr.
Dobbs Journal, September 1996. The original HTML doc (including graphics and
the source code) is also included in this archive for your convenience ;)
The latest version can be downloaded from:
http://web2.airmail.net/markn/articles/bwt/bwt.htm

Installation:
-------------
There are two drawers, one contains the plain 68000 versions, the other
contains the 68020-68060 versions of the following programs:

ari   - Arithmetic Coder
bwt   - Burrows-Wheeler Transform
mtf   - Move-To-Front
rle   - Run Length Encoder
unari - Arithmetic Decoder
unbwt - Inverse Burrows-Wheeler Transform
unmtf - Reverse Move-To-Front
unrle - Run Length Decoder

Install them anywhere you like, most preferably somewhere in your path
(e.g. C:).

Usage:
------
The compression procedure requires 5 steps:
1. rle <input >output1
2. bwt <output1 >output2
3. mtf <output2 >output3
4. rle <output3 >output4
5. ari <output4 >output
where output1...output4 are temporary files, which can be deleted afterwards.

I suggest to use the extension .bwt for files compressed using these 5 steps.

The decompression procedure also requires 5 steps:
1. unari <input >output1
2. unrle <output1 >output2
3. unmtf <output2 >output3
4. unbwt <output3 >output4
5. unrle <output4 >output
Like above, the files output1...output4 are temporary and can be deleted.

Instead of using rle and ari, you can also use other compression programs.


For comments, suggestions, bug reports, donations, etc. contact me:

André Osterhues
Meitnerweg 13/122
D-44227 Dortmund
Tel.: 0231/7519501
email: osterh00@marvin.informatik.uni-dortmund.de
www:   http://sx1.hrz.uni-dortmund.de/~andre/

 PERMSSN    UID  GID    PACKED    SIZE  RATIO METHOD CRC     STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
drwxr-x--- 55012/55000       0       0 ****** -lhd- 0000 Jun 18  1996 68000/
-rw-r----- 55012/55000    2108    6788  31.1% -lh5- c449 Jun 11  1996 68000/ari
-rw-r----- 55012/55000    3244 1003396   0.3% -lh5- 902d Jun 11  1996 68000/bwt
-rw-r----- 55012/55000    1327    2064  64.3% -lh5- 5ef4 Jun 11  1996 68000/mtf
-rw-r----- 55012/55000    1318    2264  58.2% -lh5- 0b34 Jun 11  1996 68000/rle
-rw-r----- 55012/55000    2187    6848  31.9% -lh5- 1e74 Jun 11  1996 68000/unari
-rw-r----- 55012/55000    3198 1005352   0.3% -lh5- 063d Jun 11  1996 68000/unbwt
-rw-r----- 55012/55000    1311    2052  63.9% -lh5- 3a80 Jun 11  1996 68000/unmtf
-rw-r----- 55012/55000    1307    2120  61.7% -lh5- a2be Jun 11  1996 68000/unrle
drwxr-x--- 55012/55000       0       0 ****** -lhd- 0000 Jun 18  1996 68020/
-rw-r----- 55012/55000    2020    6580  30.7% -lh5- 5870 Jun 11  1996 68020/ari
-rw-r----- 55012/55000    3150 1003128   0.3% -lh5- 0813 Jun 11  1996 68020/bwt
-rw-r----- 55012/55000    1291    1952  66.1% -lh5- 07f5 Jun 11  1996 68020/mtf
-rw-r----- 55012/55000    1295    2120  61.1% -lh5- eabb Jun 11  1996 68020/rle
-rw-r----- 55012/55000    2074    6592  31.5% -lh5- 76eb Jun 11  1996 68020/unari
-rw-r----- 55012/55000    3142 1005128   0.3% -lh5- d96a Jun 11  1996 68020/unbwt
-rw-r----- 55012/55000    1281    1952  65.6% -lh5- 8a9a Jun 11  1996 68020/unmtf
-rw-r----- 55012/55000    1262    1996  63.2% -lh5- 4876 Jun 11  1996 68020/unrle
-rw-r----- 55012/55000    1090    2256  48.3% -lh5- b06b Jun 18  1996 bwt.readme
drwxr-x--- 55012/55000       0       0 ****** -lhd- 0000 Jun 18  1996 html/
drwxr-x--- 55012/55000       0       0 ****** -lhd- 0000 Jun 18  1996 html/bwt/
-rw-r----- 55012/55000    1323    1564  84.6% -lh5- d3ea May 30  1996 html/bwt/FIGURE01.gif
-rw-r----- 55012/55000    3195    3407  93.8% -lh5- 339a May 30  1996 html/bwt/FIGURE02.gif
-rw-r----- 55012/55000    4042    4250  95.1% -lh5- a4f5 May 30  1996 html/bwt/FIGURE03.gif
-rw-r----- 55012/55000    3507    3714  94.4% -lh5- f994 May 30  1996 html/bwt/FIGURE04.gif
-rw-r----- 55012/55000    3052    3266  93.4% -lh5- ef1d May 30  1996 html/bwt/FIGURE05.gif
-rw-r----- 55012/55000    3442    3651  94.3% -lh5- d1b2 May 30  1996 html/bwt/FIGURE06.gif
-rw-r----- 55012/55000   10188   28381  35.9% -lh5- ab84 Jun 18  1996 html/bwt/bwt.html
-rw-r----- 55012/55000     471     795  59.2% -lh5- 2459 Jun 18  1996 readme.txt
drwxr-x--- 55012/55000       0       0 ****** -lhd- 0000 Jun 18  1996 src/
-rw-r----- 55012/55000    3432   10718  32.0% -lh5- 42bf Jun 18  1996 src/ari.cpp
-rw-r----- 55012/55000    3501   10304  34.0% -lh5- 564e Jun 13  1996 src/bwt.cpp
-rw-r----- 55012/55000    3388    9673  35.0% -lh5- c351 Apr 20  1996 src/bwta.cpp
-rw-r----- 55012/55000    1243    2947  42.2% -lh5- 4288 Jun 18  1996 src/mtf.cpp
-rw-r----- 55012/55000    1226    2941  41.7% -lh5- a189 Jun 18  1996 src/rle.cpp
-rw-r----- 55012/55000    3437   10429  33.0% -lh5- ac09 Jun 18  1996 src/unari.cpp
-rw-r----- 55012/55000    2889    8438  34.2% -lh5- 80d7 Jun 18  1996 src/unbwt.cpp
-rw-r----- 55012/55000    1210    2830  42.8% -lh5- 41d0 Jun 18  1996 src/unmtf.cpp
-rw-r----- 55012/55000    1232    2835  43.5% -lh5- dcb3 Jun 18  1996 src/unrle.cpp
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total        39 files   83383 4172731   2.0%            Jun 19  1996