Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!purdue!decwrl!ucbvax!SIMTEL20.ARMY.MIL!W8SDZ From: W8SDZ@SIMTEL20.ARMY.MIL (Keith Petersen) Newsgroups: comp.sys.ibm.pc Subject: GSARC - non-compatible more efficient archiver Message-ID: Date: 16 Oct 88 02:10:00 GMT Sender: daemon@ucbvax.BERKELEY.EDU Lines: 126 Just uploaded to SIMTEL20... Filename Type Bytes CRC Directory PD1: GSARC10.EXE.1 BINARY 71680 85D2H GSARC10.INF.1 ASCII 4338 CBCBH This is an interesting development. A new program that makes and extracts ARC files using a more efficient variation on LZW compression, called "Crushing". I have included the .INF file below. Beware - the ARCs it produces cannot be read by ARC, ARCE or PKUNPAK unless GSARC's compatibility switch is used. The program does work, and it does produce *signficantly* smaller ARC files. The information below is presented "as-is". I have no connection with NoGate Consulting and this posting should not be interpreted as an endorsement of yet another incompatible ARC-maker. However, it does pose an interesting question: are we to resist this just because it's incompatible - even though it is a significant step forward in compression efficiency? It will be interesting to see what SEA's reaction will be. --Keith Petersen Maintainer of the CP/M and MSDOS archives at SIMTEL20.ARMY.MIL [26.0.0.74] Arpa: W8SDZ@SIMTEL20.ARMY.MIL Uucp: {ames,decwrl,harvard,rutgers,ucbvax,uunet}!simtel20.army.mil!w8sdz ------- [GSARC10.INF] GSARC by NoGate Consulting GSARC is a utility to create and maintain file archives in compressed form. It is intended as a replacement for ARC by System Enhancement Associates and PKARC by Philip Katz. While GSARC is roughly 2.5 times as fast as ARC, speed is not the emphasis, and GSARC does not attempt to compete with PKARC in this respect. However, GSARC produces archive files that are consistently 50% to 90% of the size produced by either ARC or PKARC, and supports files created by either program. In particular, GSARC handles large text files and non-text files of any length much better than the either of these programs. In addition, the full screen version is much easier to use than ARC or PKARC. ARC popularized the LZW method of compression, which substitutes 9 to 12 bit codes for strings of characters which occur more than once in a file. PKARC made a very simple modification to the compression algorithm in ARC, by allowing codes of up to 13 bits, and hence doubled the number of allowable codes. PKARC owes some of its popularity over ARC to this, but its primary advantage is speed. GSARC, on the other hand, makes some radical changes to the LZW method. GSARC increases the range from 2 to 13 bits instead of 9 to 13, dynamically alters the compression method based on the local nature of the data, and drops only the least used codes when the code table fills, instead of all of them as ARC and PKARC do. As a result, GSARC performs much better on very large files, very small files, and on difficult files (such as .EXE and .COM files) of any length. There are 7 compression types, created variously by ARC, PKARC, and GSARC. GSARC can extract files compressed with any of these, and compress new files with the Crunched, Squashed, or Crushed types. -- No compression. Used by ARC, PKARC, GSARC. Packed Repeated byte values replaced by codes. Used by ARC. Squeezed Huffman encoding, used by ARC 5.20 and earlier. crunched Lempel-Zev compression, used by ARC 4.5 and earlier. Crunched Lempel-Zev compression, used by ARC 5.0 and later. Squashed Lempel-Zev compression, used by PKARC. Crushed Lempel-Zev compression, used only by GSARC. GSARC uses the CRC checksum to verify that the file is intact. GSARC Command Summary a = add files to archive m = move files to archive u = update files in archive f = freshen files in archive d = delete files from archive e = extract files from archive x = extract and remove files from archive l = list files in archive v = verbose listing of files in archive t = test files in archive c = convert files to new packing method Modifiers: c = make ARC compatible files. s = make PKARC compatible files. g = encrypt the file with a password. The C command extracts files from the archive and recompresses them. This is primarily of use to convert older archives created with ARC and PKARC to the better compression techniques used by GSARC. It is also possible to convert files created with GSARC so that they will be compatible with ARC or PKARC, by adding the C or S compression type modifier. GSARC is distributed as shareware. There are three versions of the compression routines in GSARC available. The first is the command line version, included in the evaluation package distributed as shareware. Registration of this version entitles you to a disk with a copy of GSARC registered in your name (which is displayed only if you type GSARC without any parameters). The second is the full screen version, which displays archive contents and file directories, and allows easy tagging of files to be compressed or extracted. Registration of this version entitles you to a disk with both the full screen and command line versions. This third, for programmers, is a library of data compression routines suitable for inclusion in your own programs. Registration of this version entitles you to a disk with files suitable for use with Turbo Pascal, C, or assembler, and the other two versions of GSARC. NoGate Consulting P.O. Box 88115 Grand Rapids, MI 49518