.. RST source for alf(1) man page. Convert with: .. rst2man.py alf.rst > alf.1 .. include:: ver.rst .. |date| date:: === alf === ------------------------------- create Atari 8-bit ALF archives ------------------------------- :Manual section: 1 :Manual group: Urchlay's Atari 8-bit Tools :Date: |date| :Version: |version| SYNOPSIS ======== alf [**--help**] | [**--version** | **-V** | [**-a** | **-o** ] [**-t[dgz]**] [**-v**] *alf-file* *file[=NAME]* [*file[=NAME]* ...] DESCRIPTION =========== **alf** creates *ALF* archives. *ALF* is a compressed archive format similar to **arc**\(1), though not compatible with it. It was used on the Atari 8-bit platform beginning in the late 1980s. The Atari executables are **LZ.COM** for the compressor and **DZ.COM** for the decompressor. **alf** is a rewrite of **LZ.COM** for modern operating systems, with added features. By default, the *alf-file* is created, and the *file*\s are compressed and added to it. If *alf-file* already existed, it is backed up by adding a **~** to the filename. The **ALF** file format only supports uppercase "8.3" filenames (Atari DOS or MS-DOS style), and does not support subdirectories. The filenames you give will be stored in the **ALF** file uppercased and truncated to fit the 8.3 scheme. This could result in duplicate filenames in the archive, if you're not careful. Filenames in the archive can be explicitly set. Each *file* can be given as *file=NAME*, where *NAME* will be the file's name in the *ALF* archive. The *NAME* is still uppercased and truncated to 8.3. OPTIONS ======= Options can be combined (e.g. **-ov** means **-o** **-v**), though the **-td**, **-tu**, **-tz** options must appear last (**-tdv** would be an error; **-vtd** is OK). -a Append to *alf-file*. The files are added to the end of the archive. Be careful not to add a file with the same name as as existing member of the archive. If *alf-file* doesn't exist, it will be created. No backup is made with **-a**. .. append to ALF file. -A Convert line endings and tabs from ASCII to ATASCII in all input files. This will corrupt any executables or non-text data files, so use with caution. There is no way to autodetect text files, unlike **unalf**. .. convert EOLs and tabs in all input files. -h, --help Show built-in help message. .. show this help message. -o Overwrite *alf-file* if it exists; do not make a **~** backup. .. overwrite ALF file if it exists (don't create file~ backup). -q Quiet operation. **alf** won't print any messages on standard output. Errors and warnings will still be printed to standard error. .. quiet. **-td** Use default **LZ.COM** timestamps (8 Dec 82 12:24). .. use default LZ.COM timestamps. **-tu** Use UTC for timestamps (default is local timezone). .. use UTC timestamps. **-tz** Use zero for timestamps. **unalf** will display ** for the date and midnight for the time. .. use zero timestamps. -v Verbose operation. Shows more information about what **alf** is doing. Can be given twice to dump the token tables (*lots* of output; for debugging only). .. verbose (-vv: debug). -V, --version Show **alf** version number and exit. .. show version number. -- End of options. The next argument is treated as the *alf-file* and any further options are files to add to the archive. .. end of options (next arg is alf-file). .. ENDOPTS EXIT STATUS =========== 0 Success. 1 Fatal error (I/O or bad command-line arguments). DIAGNOSTICS =========== Besides the standard error messages such as "no such file or directory": Filenames --------- **filename has underscore, OK on Sparta/MyDOS, not Atari DOS 2.x** Not an actual problem, unless you try to extract this ALF file on an Atari running Atari DOS 2.0/2.5, or any other DOS that doesn't allow underscores in filenames. **bad Atari filename** ** ** The filename stored in the ALF header doesn't follow the rules for Atari DOS filenames. ** will be something like "doesn't start with A-Z" or "invalid character". The filename will be printed with any unprintable characters as hex values (e.g. **$01**). With either of the above, the resulting *ALF* archive will extract with **unalf**, but will have problems with **DZ.COM** running on an Atari. Or you can just rename the files so they comply with Atari DOS filename restrictions. **duplicate Atari filename** ** You gave the same filename twice, or you gave two (or more) filenames that convert to the same "8.3" Atari filename. Example: *foo.bar* and *foo.barf* both get stored as *FOO.BAR*. You can avoid this by using the *file=NAME* syntax, e.g.:: $ alf ARCHIVE.ALF foo.bar foo.barf=FOO.BRF File Size --------- **this file is too large; only compressing the first 16MB.** The *ALF* file format doesn't support files larger than 16MB. Actually the *file format* does, but the decompressor (either **DZ.COM** or **unalf**) does not. NOTES ===== Compatibility ------------- This **alf** is *intended* to be 100% compatible with the original Atari **LZ.COM** aka **ALF.COM**, with the following differences: - There is no interactive mode. The file to create and the files to add must be given as command-line arguments. - **LZ.COM** always appends to a file that already exists. This **alf** overwrites (making a backup) by default, and can append with the **-a** option. - **LZ.COM** doesn't handle 0-byte (empty) files correctly, but **alf** does. Not that this is very useful. - Turning the screen off for speed makes no sense on modern operating systems, so there's no option for that. Note that **alf** is a complete reverse-engineered rewrite in C, *not* a port of the original 6502 code as **unalf** is. It's still being tested, and may still contain bugs. A note about the Atari filenames: **DZ.COM** is sometimes found on old disk images as **UNALF.COM**, and **LZ.COM** is sometimes called **ALF.COM** or **ALFER.COM**. I've used the original names partly out of respect for the original author, and partly to avoid confusion between my **alf**\/**unalf** and his Atari ones. Compression Characteristics --------------------------- Larger files compress better than smaller ones. Very small files will get larger when compressed. Files with lots of entropy (random garbage, files that are already compressed) will also get larger. For text files, compression is usually around 45% to 50%, which is comparable with **arc**. For SAVEd Atari BASIC, the average is a little worse: 35% to 40%. For executables, it seems to average around 30%... unless the executables are already compressed (e.g. self-decompressing), in which case they'll get bigger when compressed with **alf**. File Size Limits ---------------- **alf** (and **LZ.COM**) have a 16MB file size limit. This applies to both the input file size, and the compressed size (in case of files that grow when compressed, e.g. random data). Real Atari 8-bit files are never this large anyway, so it's a pathological case. A real Atari would take hours or even days to compress/decompress such files, and you'd have to have a hard disk and a DOS capable of handling multi-megabyte files... Performance ----------- Performance is pretty good, as of alftools-0.4.0. For small files like you'd use on an Atari (up to 50KB), it's basically instantaneous (0.008 seconds) on the author's modest i7 workstation. For a 1MB text file, it takes 0.026 sec (faster than **arc**\!). For 1MB of random garbage, it's 0.043 sec (and the resulting ALF file is 36% larger than the garbage). By comparison, **zip** takes 0.06 seconds to compress the 1MB text file, and 0.03 sec for the 1MB randomness (and the compressed file is still larger than the input, but only by 312 bytes). **arc** compresses the text file in 0.03s, and it's smart enough to *not* compress the random garbage (it uses the 'store' method, which **alf** doesn't have). Timestamps ---------- The date/time stamps stored in the archive are the **mtime**\s of the files (which is the same time **ls**\(1) shows, by default), and your local timezone is assumed (but see the **-td**\, **-tu**\, **-tz** options above). There's no way to store timezone or daylight savings info in the *ALF* file. The year stored in the *ALF* file doesn't have a Y2K problem. It does, however, have a Y2108 problem: the range is from 1980 to 2107. Files with timestamps outside this range will have a zero (invalid) date in the *ALF* header, and **unalf** will display the date as **. The timestamp only has 2-second resolution. Files with odd-numbered seconds in the *mtime* will have the number before that (1 => 0, 31 => 30, etc). This is a limitation of the *ALF* file format. Also of the *ARC* format (I didn't know that, did you?) COPYRIGHT ========= The original AlfCrunch (**DZ.COM** and **LZ.COM**) for the Atari 8-bit was released into the Public Domain. **alf** contains no code from AlfCrunch. **alf** is released under the WTPFL: Do WTF you want with this. AUTHOR ====== The original AlfCrunch for the Atari 8-bit was written by Alfred, who can be reached via the AtariAge.com forums with the username "Alfred". This **alf** was written by B. Watson . SEE ALSO ======== **unalf**\(1), **alfsum**\(1) .. include:: manftr.rst