CoDec is a simple drag and drop box application that compresses files using a huffman compression scheme. I made this program because I didn't like having to make an archive every time I wanted to compress a file, and because I don't want any more extensions clogging up my system. CoDec is FREE!
To use:
Drag your files, folders, or disks to the CoDec drop box icon. they will be compressed or decompressed automatically, as appropriate. If you double click a CoDec compressed document, it will be decompressed. The “Progress” window will display a progress bar that increments for each file processed. Click on the “Cancel” button to stop processing files.
Alternatively, you can use the “Open…” command from the file menu to select files for processing. Click on the “CoDec” button to compress/decompress folders or files/folders pointed to by aliases.
If you need to process very large numbers of files, you should increase the memory partition. The current setting of 512kb should be sufficient to handle about 2,500 files at one time. You gain about 10 files for every 1kb you add to this number.
CoDec requires System 7.0 or later, and the Thread Manager Extension. Due to the fact that it costs money to license the Thread Manager Extension from Apple Computer, Inc., I am unable to include it as part of this package. The Thread Manager Extension and Documentation is available via anonymous FTP from ftp.apple.com (/dts/mac/sys.soft/extensions). Hopefully, I will be able to get a free license for the Thread Manager, and include it with CoDec at a later time.
Details:
CoDec uses the normal Macintosh File System as its “Archive” structure, as such, there are a few things to be aware of.
• CoDec ignores invisible files. This includes icon files and the desktop databases.
• CoDec won't compress the System Folder. However, if you open anything inside the system folder with CoDec, it will be compressed. It would be a lot of trouble to check to see if something is inside the System Folder, especially if it is nested.
• CoDec does not compress alias files. If you open an alias using CoDec, the target of the alias will be processed.
• CoDec ignores aliases that it encounters during the course of processing directories. This prevents possibly recursive behavior, where an alias points to the parent folder, thus processing the parent folder repeatedly. If you really want to process the target of an alias, you should open the alias directly.
• CoDec requires exclusive read and write permission to process a file, because it will write a temporary file, and then swap it with the original. This prevents you from ever losing data when problems are encountered, but will fail under some “normal” conditions.
Known “irregularities”:
• Having multiple copies of CoDec seems to prevent the drag and drop feature from working correctly. This is a reasonable behavior on the part of the finder in an otherwise confusing situation.
• Drag and drop doesn't work when the CoDec application is on a floppy. Floppy disks don't have a desktop database, and so the finder doesn't know such neat stuff about the application. From what I'm told, ResEdit is a special case that is built into the System Software, and can have documents dropped on it while residing on a floppy.
• Alias files that are opened by CoDec will not show the correct icon until they are updated. There is no way for me to correct this behavior, since CoDec never sees the alias file, only the file it points to. You can update an alias by selecting “get info” from the finder, and clicking on the "find original" box in the lower left hand corner of the info box.
Error conditions:
There are a small number of “normal” error conditions that users may encounter. These conditions are usually caused by a full disk, or an unwritable file. In the event that one of these conditions exist, CoDec will display a message in the “log” section of the progress window, and resume processing of other files. The "problem" file will be left untouched. When CoDec quits, the contents of the log window are saved to a teach text file called “CoDec Log”.
If you get a message of the form <“filename” (type error #)>, where # is any number, please send me a copy of the" CoDec Log" file, and an explanation of the circumstances leading up to the error (what sort of disk, what sort of file, etc.).
About compression:
Huffman codes are a simple, relatively fast method of compressing and decompressing data. They are not as fast or efficient as schemes based on Lempel-Ziv compression, which is what most commercial compression programs use. LZ methods are mostly proprietary, patented, and hard to come by for free. I am looking into alternatives...
Version history:
1.0.5
• Added a StripAddress to promote correct 24 bit memory addressing.
• Corrected screen drawing when started in the background (from a script).
1.0.4
• Refined user interface.
• Rewrote file access for performance.
1.0.3
• Added checks for System 7.0 and Thread Manager at startup.
• File processing is now handled as a cooperative thread.
• Tweaked idle time handling to improve performance.
• Improved error handling.
• Streamlined user interface.
• Compiled without optimization (due to Symantec C++ bugs).
• Added log for error diagnosis.
• Fixed crash in Standard File dialog when sub-dialogs came up.
1.0.2
• optimized compression.
1.0.1
• Recompiled all files using only 68000 code generation.
• Small change to "About Box" to reflect version numbers
• Added Dialog Color Table Resource for new GetFile package.
• Reset progress bar after each operation, so it no longer draws outside of the frame.
1.0
• Initial Release
Future of CoDec:
This will be the last version of CoDec in this form. I am in the process of rebuilding it under the new Metrowerks CodeWarrior C++ compiler. The next incarnation will (tentatively) be called “Quash”. It will address several of the concerns users have mentioned, as well as a few of my own:
• Automatic launching of newly decompressed documents.
• PowerPC version.
• Modular structure, to utilize commercial compression utilities and Quicktime.
• Other types of file processing (uuencode,binhex, et al.).
• SPEED!
• Better icon.
Disclaimer, et al.:
CoDec is FREE, but not public domain. I retain the copyright to this application. CoDec may be distributed by any means so long as no fee is charged. For permission to include CoDec in any collections that will be sold for profit, please contact me at the address below.
This application is provided as is, for use at your own risk. I have made every effort to insure that it operates correctly, and I will not be responsible for any damage or loss incurred by its use, etc., etc.
Correspondence:
Feedback is always appreciated. If you have any suggestions, comments, or problems, please don't hesitate to contact me (I like mail). I've about given up trying to come up with a really good icon, any ideas? Send artwork!!! You will get appropriate credit.
