[This is a post I made to comp.compression after consulting the
authors of lzhuf.c (which readlzh.c is based on).]


From: Russell Marks <russell.marks@spam^H^H^H^Hntlworld.com>
Newsgroups: comp.compression
Subject: lzhuf.c licence update
Message-ID: <Ccse7.1311$tG2.106880@news6-win.server.ntlworld.com>
Date: 15 Aug 2001 11:31:54 +0100

Recently I posted asking about the authors/licence of `lzhuf.c'. I've
contacted most of the authors since, so I thought I'd post the
results. My main question to them was whether I could use lzhuf.c in a
GPL'd program, but I did also try to clear up the original licence for
those who might want to use it in BSD-licenced programs, or whatever. [1]

Kenji Rikitake said, "my contribution to lzhuf.c is very little and I
will not claim any objection for the usage".

Haruhiko Okumura (or should I say, Professor Okumura :-)) said,
initially referring to the "Permission granted for non-commercial use"
comment that Kenji asked to be added in 1989, "I was unaware that
Kenji had added that phrase. I (and as far as I know, Yoshi) have
never been that strict; LHarc and LHA have been included in many
commercial software packages. There should be no problem if you take
LZHUF.C as ether GPL'd or LGPL'd."

When I asked what licence I should say lzhuf.c was under, suggesting
his old terms for (among others) lzari.c which are "Use, distribute,
and modify this program freely", he agreed.

Haruyasu Yoshizaki (Yoshi) has proven difficult to contact. I've
emailed him at an address Prof. Okumura suggested might be worth
trying, but from what I've read on the web about how busy he's said to
be (and how he doesn't really want email, which explains why an email
address for him was difficult to come by), I don't expect a reply.

So, since lzhuf.c is significantly based on Okumura's lzari.c [2]
(which has always had the above licence), I'm going to go with his
opinion on the matter, and assume that Yoshi would not object. (Not
least because Prof. Okumura said `I can assure you that his intention
has always been "try it, and improve it."')

In summary:

The authors I've been able to contact agree to the licence "Use,
distribute, and modify this program freely" - "freely" here meaning
`without restriction', and not being a reference to price. The
remaining author I've not been able to contact, but the licence
appears consistent with his intent, and was also the licence on the
original program which he modified (lzari.c).

-Rus.

[1] But note that LZH compression is unfortunately patented (US patent
no. 4,906,991 covers it) - decompression isn't, so I don't expect this
to affect my program. And unless you have a specific need for LZH like
I did, something like zlib would generally be a better choice anyway.

[2] The version of lzhuf.c referred to by the `author' of the CP/M
port made this rather clearer:

 * LZSS coded by Haruhiko OKUMURA
 * Adaptive Huffman Coding coded by Haruyasu YOSHIZAKI
 * Edited and translated to English by Kenji RIKITAKE
