From:	ao950 AT FreeNet DOT Carleton DOT CA (Paul Derbyshire)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Problems using allegro
Date:	16 Mar 1997 12:02:01 GMT
Organization:	The National Capital FreeNet
Lines:	37
Message-ID:	<5ggnfp$7dv@freenet-news.carleton.ca>
References:	<19970312 DOT 054752 DOT 7495 DOT 0 DOT fwec AT juno DOT com> <19970315 DOT 101544 DOT 7423 DOT 14 DOT fwec AT juno DOT com> <332B9F32 DOT 79F2 AT pobox DOT oleane DOT com>
Reply-To:	ao950 AT FreeNet DOT Carleton DOT CA (Paul Derbyshire)
NNTP-Posting-Host:	freenet5.carleton.ca
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Francois Charton (deef AT pobox DOT oleane DOT com) writes:
> Benjamin D Chambers wrote:
>> 
>> Wasn't LZW Lempel-Ziv-Welsh?  (I can never remember their names, but at
>> least I know what they start with :)
>> 
> 
> Yes, LZW is based on a algorithm nicknamed LZ78. It has been described in 
> the article "Compression of individual sequences via variable 
> rate coding", by Lempel and Ziv (IEEE transactions on Information Theory, 
> vol.24 Nr 5, pp 530-536). 
> 
> Terry Welsh was the one who discovered a practical implementation of this 
> algorithm (which uses a stack structure for creating the coding 
> dictionnary). He published his results in 1984 in "A technique for high 
> performance data compression", (IEEE Computer, Vol.17, nr6, pp8-19).
> 
> The patent for LZW was applied for by Welsh, who worked at the time for 
> the Sperry Research Center, now part from Unisys.
> 
> Francois
> 


What about the public-domain LZSS? Is the compression comparable to LZW?
the speed? What's the algorithm?

LZSS is used in PKUNZIP and in ALlegro's packfiles, which are essentially
"magic PKZIP files" that uncompress when opened for file access and
compress when closed.

--
    .*.  Where feelings are concerned, answers are rarely simple [GeneDeWeese]
 -()  <  When I go to the theater, I always go straight to the "bag and mix"
    `*'  bulk candy section...because variety is the spice of life... [me]
Paul Derbyshire ao950 AT freenet DOT carleton DOT ca, http://chat.carleton.ca/~pderbysh

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