UNZIP and ZIP for CP/M Z80

This repository contains versions of UNZIP and ZIP for various flavours of CP/M written in Zilog Z80 assembler.

Support has been added for the Deflate compression algorithm so that decompression of ZIP archive files created with MS-DOS PKzip 2.04g and Info-ZIP (the open-source version of ZIP that's used by Unix/Linux and included with Microsoft Windows and macOS) can now be extracted.

(Older versions of the CP/M UNZIP program from various CP/M archive sites can only be used to unpack .ZIP files whose contents were added using the Compressed or Stored methods as used by PKZip for MS-DOS Version 1.x.)

The latest UNZIP release is V1.5-7 (for CP/M) or V1.8-7 (with Z-system enhancements) and may be downloaded in CP/M library file format from -

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzip157.lbr

or

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzip187.lbr

Simeon Cran's version (UNZIPZ) for Z-system has also been updated as V0.4-1 and is available from -

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzipz04.lbr

A utility to create ZIP files natively under CP/M (using the Stored method and no file compression) was recently added to this repository by Jonathon Harston. You can get it from

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/zip101.lbr

Transfer these .LBR files to your CP/M system, then use a program like NULU¹ to extract their contents. Some of the extracted files may be compressed as indicated when the second file type character is a Q (squeezed), Y (Limpel-Ziv-Welch or LZH compressed) or Z (crunched). You'll need to use the appropriate decompression tool² to decompress them.

Bug Fixes and Enhancements

In reverse chronological order.

December 28, 2023

Lars Nelson has provided the following updates to Jonathon Harston's CP/M ZIP file creation utility -

• Fixed a problem where the computed CRC for some but not all files was not being written into the Local File Header especially on CP/M 2.2 and compatible systems. This caused a problem for CP/M unzip programs since they use the information in the Local File Header to extract files. Lack of a valid CRC causes the unzip programs to skip the file. Note, the central directory was correct so on PCs or Macs all files could be extracted.

• Added the ability to get file modification date from CP/M Plus and CP/M 2.2 using routines from the Z-system libraries DSLIB and ZSLIB. This necessitated making the code relocatable.

The updated version is ZIP101. You can download the full distribution from the CP/M library file from

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/zip101.lbr

Or just the binary from ZIP101.COM and the updated source file from ZIP101.Z80.

To rebuild from source you can use Alex Hawley's ZMAC & ZML³ (as opposed to some other assembler named ZMAC) or Hector Peraza's ZSM4⁴ and standard Digital Research CP/M 3 linker LINK. The libraries DSLIB.REL, ZSLIB.REL and SYSLIB.REL are required to be in the default directory (or modify the sourcecode to explicitly specify their location).

zmac zip101
zml zip101

or

zsm4 =zip101.z80
link zip101

October 22, 2023

Stefano has contributed some code optimisations to the CP/M UNZIP program. I've bumped the version number to v1.5-7. If you notice any issues with this version, please report them.

October 13, 2023

Minor updates to Jonathon Harston's UNZIP V1.5-6 and the CP/M ZIP v1.00 program to include the date in the usage output (when you run the programs with no parameters). I've also modified the sources so that they can be built using the Microsoft Macro-80 and Hector Peraza's ZSM4 Macro Assemblers.

August 31. 2023

The CP/M version V1.5-6 has been modified by Jonathon Harston to -

• Junk (ignore) file paths (if present in the ZIP file),

• Return to the command processor instead of warm-booting on exit,

• Added [Q]uiet and [O]verwite options to extract files silently and to overwrite existing files of the same name, and

• The sign-on message is now only output when run without command-line parameters.

In addition, the ZIPDIR utility has been updated to display a 4-digit year for file datestamps, and the CRC as a 32-bit number. This new version 1.5 is available from

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/zipdir15.lbr

Jonathon Harston's sourcecode for a CP/M ZIP utility has also been added as ZIP100.Z80.

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/zip100.lbr

September 19, 2021

The CP/M version was not checking output filenames to ensure they were in uppercase. This has been fixed, and the version bumped to V1.5-5.

June 14, 2021

Issue #1 fixes to the Z-System UNZIP by both Lars Nelson and myself have resulted in a new V1.8-7 version. The UNZIP187.* files (and the library containing them) have been added.

December 23, 2020

Some testing has revealed a problem UnDeflating small text files with the Z-System version V1.8-6. Lars has debugged and corrected this issue. The V1.8-6 version files (and the library containing them) have been updated. UNZIPZ V0.4-1 and the V1.5-4 version are not affected.

December 9, 2020

Lars Nelson has been busy! He's updated Simeon Cran's UNZIPZ to include the optimised bit manipulation and the table-based CRC routines by Russell Marks to give a significant speed improvement (estimated 45% faster than the UNZIPZ V0.3-4 version). This latest version is designated V0.4-1 and can be downloaded from

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzipz04.lbr

Also, Lars has updated the Z-system version to produce a .ZIP file contents listing in a format that includes compressed/uncompressed file size, compression method, modification time-stamp and the 32-bit CRC.

This version V1.8-6 can be downloaded from

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzip186.lbr

November 30, 2020

Lars Nelson has migrated the updates into Simeon Cran's UNZIPZ version so that it also now supports the UnDeflate algorithm. The source files and a prebuilt CP/M .COM file have been included in the unzip folder. This new version has been designated at V0.3-2. As usual you can grab these files in the CP/M library file from -

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzipz03.lbr

November 18, 2020

Lars Nelson has incorporated file datestamping to set each extracted file's date on CP/M formatted disks with Time-Stamps enabled. This should work with DateStamper, ZSDOS, CP/M Plus (and ZPM3) and MP/M.

The Z-System aware version number has been bumped to V1.8-5.

There's one remaining issue involving the calculation of a cyclic redundancy check (CRC) value for files that are not being extracted (i.e. listing contents of a .ZIP file). In the older V1.5-2 (and later revisions) Martin removed the CRC calculation when listing a .ZIP file's contents. Lars has tried to restore this code in V1.8-5 but it is calculating the wrong value for files not being extracted. As a work-around, these skipped files are now being treated as "Stored" files for now.

You can grab this latest version in a CP/M format library file from -

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzip185.lbr

November 11, 2020

Lars Nelson has fixed an UnDeflate issue as well as added code to strip pathnames from filenames and clear bit 7 of filename characters. This version builds with the supplied UNZIP184.SUB (for ZSM4 and DR LINK) or SLR184.SUB (using SLR Z80ASM and SLRNK).

Once again, I've updated the source and library file (still at v1.8-4) so fetch a new copy if you've an older version.

Also a later Z-System version of ZIPDIR has been added. Download from ZIPDIR14.LBR

November 4, 2020

Lars has fixed the "zero-length file CRC error" for the Z-system v1.8-4 version. Updated UNZIP184.Z80, the binary and library for this version only. Also included an updated version of ZIPDIR.LBR to correctly report .ZIP file entries compressed with the Deflate method.

October 31, 2020

Lars Nelson has ported the v1.5-4 updates to the Z-system version (with the exception of the >255 character filename check). As usual, the individual files are in the unzip folder or grab the v1.8-4 version in a CP/M .LBR file from

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzip184.lbr

I've also included the Z-system libraries in their original binary distribution format .LBR files (should you wish to rebuild from source code). They are

• LIBS45A.LBR - the library containing .REL versions of SYSLIB, Z3LIB and DSLIB in both Microsoft M80/DR LINK and SLRNK file formats.

• LBRHL45A.LBR - the help files for LIBS45A.LBR

• ZSLIB36.LBR - the supplemental routines for programmers.

For testing, I re-linked UNZIP184.COM natively under Z3PLUS Vers. 1.02 (the Z-system variant for CP/M-Plus) using the ZSM4 assembler and Digital Research's LINK using the submit file UNZIP184.SUB.

October 30, 2020

Lars Nelson has ported the v1.5-2 bug fixes and UnDeflate enhancements to the Z-system (ZCPR 3.x) branch, resulting in v1.8-2.

Based on initial testing, this version (using a 2K buffer and Z-system libraries) has better performance than v1.5-2 (and later).

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzip182.lbr

October 18, 2020

Some further speed optimisations by Russell Marks.

• Further slight optimisations to bit-readers,

• Backport some unzip 1.8 changes (buffer-overrun fixes, bit 7 strip on output filenames, less frequent ^C checking, and low-memory message), and add various comments.

• Use self-modifying code with an unrolled end loop in rdbybits, and add a "rd1bit" macro, for about a 12% speed improvement on overall extraction time compared to version 1.5-3.

• Fix long-filename buffer overrun, for filenames longer than 255 characters.

• Backport Howard Goldstein's buffer-overrun fixes from unzip 1.8 - previously, a 255-byte buffer was repeatedly used to read up-to-65535-byte inputs.

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzip154.lbr

October 15, 2020

Russell Marks has contributed speed optimisations to the UnDeflate algorithm to significantly boost performance (by more than 30%).

• A new routine rdbybits now processes eight or fewer bits.

• Checks whether the TPA size is large enough for UNZIP's tables

• Use a table-based CRC algorithm. This increases the CP/M binary size by about 1Kbyte.

I've bumped the version number to 1.5-3 and the latest updated sourcefile as UNZIP153.Z80. The source and CP/M binary are also available in a CP/M format library file from

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzip153.lbr

September 2020

Martin has posted some more updates and added support to decompress ZIP file entries compressed with the Deflate algorithm.

The changelog is -

• Fix extraction of zero-length files.

• Skip to the next file header if the compression method is unknown

• Fix readbits when a full word (16 bits) is read - in preparation for implementing the unDeflate algorithm.

• Fix mis-ordering of variables. Code makes the assumption that "bitbuf" is the byte before "bleft".

• Allow the relocation of the input buffer.

• Make the output buffer size dynamic.

• Implement the UnDeflate algorithm - based on the work by Keir Fraser's HiTech-C code at https://github.com/keirf/Amiga-Stuff/blob/master/inflate/degzip_portable.c

You'll find the updated sourcefile as UNZIP152.Z80 which you can also get in a CP/M format library file from

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzip152.lbr

June 2020

Recently Martin posted two bug fixes to the unshrink and unimplode routines in the comp.os.cpm USENET group that fix two long outstanding bugs (1-Jun-2020 and 15-Jun-2020).

I've incorporated Martin's fixes into a new sourcefile UNZIP151.Z80 and also updated the original sourcecode for Version 1.2 into a renamed file UNZIP121.Z80

I've also updated the Z-system Version 1.8 into a renamed source file UNZIP181.Z80 and rebuilt the corresponding .COM file using the Z-system libraries extracted from LIBS45A.LBR and ZSLIB36.LBR

For a discussion of the fixes - please refer to the following postings at the Google Groups archive of the comp.os.cpm newsgroup -

• Un-shrink fix https://groups.google.com/forum/#!topic/comp.os.cpm/B0A4x59SX44

• Un-implode fix https://groups.google.com/forum/#!topic/comp.os.cpm/rpjA1Q6RtDc

The new Z80 CP/M executable has been built using Hector Peraza's ZSM4 assembler⁴ and Digital Research's LINK as UNZIP151.COM using the following commands -

zsm4 =unzip151.z80
link unzip151

A new library file (without compressed entries) containing the fixes is unzip151.lbr and can be downloaded from

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzip151.lbr

Also, the new Z-system (ZCPR 3.x) UNZIP Version 1.8-1 is in the library unzip181.lbr and can be downloaded from

https://raw.githubusercontent.com/agn453/UNZIP-CPM-Z80/master/unzip/unzip181.lbr

The Z-system version has been built using the submit file (also included as UNZIP181.SUB) -

; Build new version of UNZIP181 using SLR Z80ASM and SLRNK
; using Z-System libraries from LIBS45A.LBR and ZSLIB36.LBR
;
z80asm unzip181/6
; Load ASEG after CSEG - verify CSEG size is 0d7b
; and use ASEG at 0d7b + 0100 +1 to be sure
slrnk /a:0e7c,/p:100,unzip181,unzip181/n/e

Background

Files have been extracted from the following distribution archives -

• UNZIP15.LBR from the Public Domain software library originally distributed on 1-Jun-1991 as Version 1.5. I obtained this from the Walnut Creek CP/M Software CD-ROM at

http://www.classiccmp.org/cpmarchives/cpm/Software/WalnutCD/cpm/utils/arc-lbr/unzip15.lbr

Version 1.5 incorporates modifications by Howard Goldstein on 1-Jun-1991 plus those by Bruce Morgan on 16-May-1991 (Version 1.4) and Gene Pizzetta on 12-May-1991 (version 1.3); and includes the original Version 1.2 source-code by David Goodenough dated 3-Jul-1990.

• UNZIP18.LBR has further modifications by Howard Goldstein for Z-system (ZCPR 3.x) with improved file I/O performance and buffering. It was obtained from

http://www.classiccmp.org/cpmarchives/cpm/Software/WalnutCD/jsage/znode3/uploads/unzip18.lbr

Notes

Other Zilog Z80 assemblers/linkers can also be used (e.g. SLR Z80ASM/SLRNK or even Microsoft M80/L80) - however, they may create a .COM file with data segment storage included.

Also, there are other UNZIP programs for CP/M that use the same unpacking code derived from the Version 1.2 source-code. They are not fixed.

--

Footnotes

1. A copy of the CP/M library file extraction tool NULU.COM may be downloaded here or the full NULU distribution can be downloded from the cpmarchives site as NULU152A.LBR ↩

2. CP/M native tools for decompressing are LT31.COM (which will extract and uncrunch/unsqueeze/unLZH directly from .LBR file members) available in LT31.LBR or UCRLZH20.COM available in CRLZH20.LBR. ↩

3. Alex Hawley's ZMAC & ZML are the traditional mainstay Z80 Assembler and Linker for Z-system program development. You can download a ZIP file distribution of it from http://www.cpm.z80.de/develop/zmac.zip ↩

4. The source-code, documentation and executable for the ZSM4 Z80/Z180/Z280 Macro Assembler may be obtained from https://github.com/hperaza/ZSM4 ↩ ↩²