delorie.com/archives/browse.cgi   search  
Mail Archives: djgpp/2009/05/26/02:45:11

X-Authentication-Warning: delorie.com: mail set sender to djgpp-bounces using -f
From: Rugxulo <rugxulo AT gmail DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Gzip 1.2.4 "-9" hack (improved compression) / Unzip 6.0
Date: Mon, 25 May 2009 23:38:04 -0700 (PDT)
Organization: http://groups.google.com
Lines: 40
Message-ID: <26f4410e-07ea-4a16-87b2-269265674c39@m17g2000vbi.googlegroups.com>
NNTP-Posting-Host: 65.13.115.246
Mime-Version: 1.0
X-Trace: posting.google.com 1243319884 29666 127.0.0.1 (26 May 2009 06:38:04 GMT)
X-Complaints-To: groups-abuse AT google DOT com
NNTP-Posting-Date: Tue, 26 May 2009 06:38:04 +0000 (UTC)
Complaints-To: groups-abuse AT google DOT com
Injection-Info: m17g2000vbi.googlegroups.com; posting-host=65.13.115.246;
posting-account=p5rsXQoAAAB8KPnVlgg9E_vlm2dvVhfO
User-Agent: G2/1.0
X-HTTP-UserAgent: Opera/9.64 (Windows NT 6.0; U; en) Presto/2.1.1,gzip(gfe),gzip(gfe)
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

The ultimate .gz compressor is probably 7-Zip / p7zip, but it's very
very slow. But if you want better compression without the huge speed
penalty, you can compile Gzip 1.2.4 (only) with Ilia Muraviev's "-9"
hack (two-byte lookahead or whatever). As he calls it, it's a five-
minute hack, so it's not ported to 1.3.12 or Zlib. But hey, it
improves the compression while still keeping older levels for fastest
speed ratio. So, if you want a bit better speed, try his modified
DEFLATE.C (and use -DNO_ASM and remove all mentions of match.S from
the makefile, and fix the silly tab error, and it should compile and
work correctly). And yes, it's 100% compatible output.

Basically, it compresses better than typical Gzip "-9" but somewhat
slower:


                                         enwik8          enwik9
gzip124hack           -9    36,273,716       321,050,648
gzip 1.3.5               -9    36,445,248       322,591,995


http://www.encode.ru/downloads/gzip124hack.zip  (original patched
DEFLATE.C and Win32 binary)

http://rugxulo.googlepages.com/gzhakwat.zip        (311k, includes
everything necessary, mainly full sources + patch + OpenWatcom DOS +
Win32 compiles, this was before I knew why DJGPP wasn't byte
identical, don't forget -DNO_ASM and don't use match.S !!!)

P.S. Since I'm talking about compression, Info-Zip 6.0 was *finally*
released last month (and Zip 3.0 last year and 3.1b beta srcs
recently), default package includes MSC 16-bit and  :-)  DJGPPv2  :-)
32-bit .EXEs (with Bzip2 method support). Not sure why no default
binaries for Zip 3.0, I did compile for them (minor bug on DR-DOS, MS-
DOS 6.22 re: "-f", probably still unresolved, bah), but anyways, it's
easy to build.

http://www.info-zip.org
http://www.sourceforge.net/projects/infozip
ftp://ftp.info-zip.org/pub/infozip/msdos/unz600x3.exe
ftp://ftp.info-zip.org/pub/infozip/src/

- Raw text -


  webmaster     delorie software   privacy  
  Copyright 2019   by DJ Delorie     Updated Jul 2019