DWC - Revision history

Jsummers: /* Identification */

2025-07-27T16:24:48Z

‎Identification

Jsummers: /* Sample files */

2025-07-27T16:14:47Z

‎Sample files

Jsummers: Added LZW info

2025-07-27T16:12:21Z

Added LZW info

Sembiance: sample files

2024-07-30T13:27:16Z

sample files

Jsummers at 13:34, 19 October 2023

2023-10-19T13:34:23Z

Jsummers: Deleted a link (moved to ARC)

2023-10-19T13:24:37Z

Deleted a link (moved to ARC)

Jsummers: /* Identification */

2021-11-12T20:57:19Z

‎Identification

Jsummers at 20:45, 12 November 2021

2021-11-12T20:45:42Z

Dan Tobias at 00:25, 20 February 2020

2020-02-20T00:25:41Z

Jsummers at 15:34, 14 February 2020

2020-02-14T15:34:18Z

@@ Line 91: / Line 91: @@
 == Identification ==
-Files end with ASCII "{{magic|DWC}}". There is no header or signature at the beginning of the file.
+While the software's decoder is more tolerant than this, it seems likely that all DWC files end with ASCII "{{magic|DWC}}", and have bytes {{magic|1b 00 22}} beginning 27 bytes from the end of the file.
-−
-The known versions of DWC always seem to produce files having bytes {{magic|1b 00 22}} beginning 27 bytes from the end of the file. However, the software does not require this, and old versions still need to be evaluated.
 == Specifications ==

← Older revision		Revision as of 16:14, 27 July 2025
Line 106:		Line 106:

	== Sample files ==		== Sample files ==
		+	* [https://archive.org/details/pcmania-disquetes PCmanía Disquetes] → 16/PCC/*.DWC
		+	* [{{DiscMasterURL\|browse/33128/prog64_69.zip/prog64_69/PROG_68/GTA-WIU.ZIP/PCW_UTIL}}] → /.DWC
		+
		+	Self-extracting archives:
	* {{DexvertSamples\|archive/dwcSelfExtracting}}		* {{DexvertSamples\|archive/dwcSelfExtracting}}

@@ Line 14: / Line 14: @@
 The documentation says that in 1988 the compressor/decompressor source code rights were sold to a company called DS Technologies.
-== File structure ==
+== Format details ==
   DWC archive format overview
@@ Line 75: / Line 77: @@
    +csize           pathsize  Path, NUL-terminated
    +csize+pathsize  cmtsize   File comment, NUL-terminated
 == Self-extracting archives ==

← Older revision		Revision as of 13:27, 30 July 2024
Line 95:		Line 95:
	** {{CdTextfiles\|nightowl/nopv06/028A/DWC_A501.ZIP\|Ver. A5.01}} (1988-05-31)		** {{CdTextfiles\|nightowl/nopv06/028A/DWC_A501.ZIP\|Ver. A5.01}} (1988-05-31)
	** [{{SACFTPURL\|pack\|dwc-a510.exe}} Ver. A5.10] (1990-03-07)		** [{{SACFTPURL\|pack\|dwc-a510.exe}} Ver. A5.10] (1990-03-07)
		+
		+	== Sample files ==
		+	* {{DexvertSamples\|archive/dwcSelfExtracting}}

@@ Line 6: / Line 6: @@
 }}
 '''DWC''' is a compressed archive utility and file format that was patterned after [[ARC (compression format)|ARC]], but is not compatible with that format. It was designed to be faster and more compact than ARC, but have similar functionality. Its compression scheme is based on [[LZW]].
 == Discussion ==
@@ Line 19: / Line 17: @@
   DWC archive format overview
    This documentation contains educated guesswork derived from
@@ Line 30: / Line 29: @@
   Archive Trailer segment
-   Let EOF = the DWC file size.
+   Let EOF = the DWC file size. (More precisely, the file position after
    Offset   Size Label     Description
@@ Line 74: / Line 75: @@
    +csize           pathsize  Path, NUL-terminated
    +csize+pathsize  cmtsize   File comment, NUL-terminated
 == Identification ==
@@ Line 88: / Line 94: @@
 ** {{CdTextfiles|nightowl/carrs/015A/DWC_A495.ZIP|Ver. A4.95}} (1988-03-15)
 ** {{CdTextfiles|nightowl/nopv06/028A/DWC_A501.ZIP|Ver. A5.01}} (1988-05-31)
-** [https://www.sac.sk/download/pack/dwc-a510.exe Ver. A5.10] (1990-03-07)
+** [{{SACFTPURL|pack|dwc-a510.exe}} Ver. A5.10] (1990-03-07)

← Older revision		Revision as of 13:24, 19 October 2023
Line 89:		Line 89:
	** {{CdTextfiles\|nightowl/nopv06/028A/DWC_A501.ZIP\|Ver. A5.01}} (1988-05-31)		** {{CdTextfiles\|nightowl/nopv06/028A/DWC_A501.ZIP\|Ver. A5.01}} (1988-05-31)
	** [https://www.sac.sk/download/pack/dwc-a510.exe Ver. A5.10] (1990-03-07)		** [https://www.sac.sk/download/pack/dwc-a510.exe Ver. A5.10] (1990-03-07)
−
−	~~== Further reading ==~~
−	* [http://ascii.textfiles.com/archives/2398 ARC/ZIP Perspective by Dean W. Cooper]

← Older revision		Revision as of 20:45, 12 November 2021
Line 15:		Line 15:

	The documentation says that in 1988 the compressor/decompressor source code rights were sold to a company called DS Technologies.		The documentation says that in 1988 the compressor/decompressor source code rights were sold to a company called DS Technologies.
		+
		+	== File structure ==
		+
		+	DWC archive format overview
		+
		+	This documentation contains educated guesswork derived from
		+	observing the behavior of DWC (mainly v5.10). It extends and
		+	corrects some earlier descriptions of the format.
		+
		+	- Byte order is little-endian.
		+	- CRC algorithm is [[CRC-16#CRC-16/ARC\|CRC-16/ARC]].
		+	- Sizes and offsets are in bytes, unless otherwise noted.
		+
		+	Archive Trailer segment
		+
		+	Let EOF = the DWC file size.
		+
		+	Offset Size Label Description
		+	------ ---- ----- -----------
		+	EOF-27 2 tsize Size of trailer (usually 27, larger OK)
		+	EOF-25 1 fhsize Size of each member file header (usually 34,
		+	larger OK, slightly smaller maybe OK)
		+	EOF-24 13 Name of header file ("h" command), NUL-
		+	terminated
		+	EOF-11 4 Archive timestamp ([[Unix time]])
		+	EOF-7 4 nmembers Number of member files
		+	EOF-3 3 "DWC" signature
		+
		+	Member File Headers segment
		+
		+	Sequence of nmembers headers, each fhsize bytes, starts at
		+	EOF-tsize-(fhsize×nmembers).
		+
		+	Member File Header
		+
		+	Offset Size Label Description
		+	------ ---- ----- -----------
		+	+0 13 Base filename, NUL terminated
		+	+13 4 Original size
		+	+17 4 Timestamp ([[Unix time]])
		+	+21 4 csize Compressed size
		+	+25 4 fdpos Offset (from start of file) of File Data segment
		+	+29 1 Low 4 bits: Compression method (1=Crunched,
		+	2=not compressed).
		+	0x40 bit: Set if file is encrypted.
		+	+30 1 cmtsize Size of comment field
		+	+31 1 pathsize Size of path field
		+	+32 2 CRC of compressed (and potentially encrypted)
		+	data
		+
		+	File Data
		+
		+	One segment per member file. Starts at fdpos.
		+
		+	Offset Size Description
		+	------ ---- -----------
		+	+0 csize Compressed data
		+	+csize pathsize Path, NUL-terminated
		+	+csize+pathsize cmtsize File comment, NUL-terminated

	== Identification ==		== Identification ==

@@ Line 10: / Line 10: @@
 == Discussion ==
-DWC was created by Dean W. Cooper in 1986 as a higher performance alternative to the [[ARC (compression format)|ARC]] (both ARC & PKARC) and [[ZOO]] file archiving tools. The file COMPARE.DOC (in e.g. version A5.01) reports both compression and time improvements over DWC's competitors.
+DWC was created by Dean W. Cooper in 1986 as a higher performance alternative to the [[ARC (compression format)|ARC]] (both ARC & PKARC) and [[Zoo]] file archiving tools. The file COMPARE.DOC (in e.g. version A5.01) reports both compression and time improvements over DWC's competitors.
 Source code for some versions prior to A5.01 was apparently made public, but we have not located any copies.

← Older revision		Revision as of 15:34, 14 February 2020
Line 28:		Line 28:
	** {{CdTextfiles\|nightowl/nopv06/028A/DWC_A501.ZIP\|Ver. A5.01}} (1988-05-31)		** {{CdTextfiles\|nightowl/nopv06/028A/DWC_A501.ZIP\|Ver. A5.01}} (1988-05-31)
	** [https://www.sac.sk/download/pack/dwc-a510.exe Ver. A5.10] (1990-03-07)		** [https://www.sac.sk/download/pack/dwc-a510.exe Ver. A5.10] (1990-03-07)
		+
		+	== Further reading ==
		+	* [http://ascii.textfiles.com/archives/2398 ARC/ZIP Perspective by Dean W. Cooper]