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PREM/PRES

2015-04-26

This is a straightforward compression library written from scratch
and a compress/gzip lookalike front end using the library, both
created back in 1990.

This suite was specifically developed for use under 16-bit Unix,
namely Venix/86. It has very modest and tunable memory requirements.

The algorithm uses a simplified approach based on
 Fiala,E.R., and Greene,D.H. Data compression with finite windows,
   Comm.of the ACM, 32(4), 490-505, April 1989.

Any possible related patents should be void by now (2015).

The code has been compiled and used on several platforms,
including Venix-2.0/8086, SUN Solaris 2.x/SPARC, Linux/i386.

This suite largely outperforms the "compress" utility compiled for
ELKS. Testing on a Debian i386 Linux:

$ cat /bin/* | time elksemu compress -v >/dev/null
Compression: 17.11%
real    0m 3.45s
user    0m 0.02s
sys     0m 3.41s
$ cat /bin/* | time elksemu pres >/dev/null
Compression: 49%
real    0m 1.74s
user    0m 0.02s
sys     0m 1.69s

The B_PREM directory contains some old test code pieces, not needed
otherwise.

PREM contains the library, PRES contains a couple of front ends, one
is a "compress" lookalike for file/stream compression, the other is for
writing/reading large archives on floppy-like media.

I release the code included in this archive under the following terms:

Copyright (c) 1990-2015 RL @ Aetey Global Technologies AB

All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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