home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Crawly Crypt Collection 1
/
crawlyvol1.bin
/
utility
/
archiver
/
lzh201le
/
afx_e.doc
next >
Wrap
Text File
|
1991-09-02
|
6KB
|
153 lines
AFX Version 1.1 19.08.91
------------------------------------------------------------------------
Automatic
File
eXtractor
This program enables any other program to work with compressed files. If
AFX is installed, the program is not able to distinguish between compress
and uncompressed files. The files are decoded at the time they are loaded.
AFX will only decode that part of the files, a programm actually needs, this
means AFX needs only a small amount of memory (in this distribution: 24KB).
1. Installation
Simply copy AFX.PRG into your auto-folder and restart the system.
2. Compression of files
I have planned to use standard lzh-files but this has the disadvanage
that LHarc will no longer work with AFX installed. This is because it
is impossible for LHarc to read a compressed lz5-file. For that reason,
the method is set to -afx-.
LHarc 2.01d and newer versions have a special command for AFX. The
difference is
- every file is packed into itself, so you don't have to specify an
archiv.
- The method is set to -afx- instead of -lz5-
To compress one or more files, simply use the command "c", eg. after
a double click on LHARC.TTP type:
c filenames
to compress one or more files or
c -r filenames
to recursivly compress one or more files.
For example: If you want to pack ALL .RSC-Files start LHarc from root and
type
c -r *.rsc
2. How it works
If a program opens a file, AFX will intercept this command and looks if
this file is stored in compressed form. This means, the file must contain
a complete LHarc headers with correct checksum and the method must be
-afx-. If the file is compressed, AFX will rememer this and intercept
every fread, fseek and fclose-command for this file and translate them
into several fread and decode-commands.
AFX needs some memory to work, since not all programs like it if the
amount of available memory is decrese in an open-command, AFX has its
own memory pool. In this version it contains 20 KB -- enough for 2
open files. If you have more than 2 files opened at once, AFX will
start to work with system-memory.
AFX in its present state is not able to decode and start program-files.
For this we have PFXPAK, since PFXPAK has not that much "housekeeping"
to do, it works faster than AFX.
It is not possible to write on compressed files. Compression can only
be done with the whole file. If you change the first byte of a compressed
file, you will eventually have changes in the whole file. For that
reason, AFX would have to recompress the whole file every time a byte
is changed (or it has to recompress it after it is closed). Since
comrpession needs much time or much memory, this should be done with
a seperate program.
3. Speed
All mesurements are made with a Megafile 30 and 4KB Buffersize and
an 187KB text-file. AFX is faster if the file has a good compression
rate and slower if it has a bad compression rate.
Short files or short parts of a large file (less than 10KB) are processed
at a speed of about 55KB per second (depending on the file).
If the file or the part of the file is larger than 10KB only the first
4KB and the last some hundred bytes of it are read in low speed. The
middle part is read in high speed. The test file is read at a reat
of about 100KB per second.
4. Future-versions
- If a write on a compressed file occures, the whole file should be
docoded on disk first.
- I am thinking of a new format to increase decoding-speed, eventually
increasing code-size.
- I am thinking of a special AFX-Packer.
5. History
Version 1.3
- More speed in decoding files.
Version 1.2
- Should make no problems with any programs.
Version 1.1
- 1.0 lookked, if files like CON: or PRN: deliver compressed data. The
effect was, that it was possible to type in data, or, the program
simply hangs.
- Sometimes, AFX will start without delay.
- More speed.
Version 1.0
- First working version. Before I delivered this version, I packed all
my source-codes and texts and worked with tem a few days.
6. Shareware
This is not free software. If you paied a public-domain vendor for
this program, you paid for the service of copying and shipping the
program, not for the program itself. This means that nothing ever
get to the autors from this sale.
You are allowed to copy AFX and to give it to your friends or a
PD-Library. It is not allowed to sell this program. It is not allowed
to copy this program without its documentation or without the
registration-form.
Your version has the same functions as the registered version, so
you are able to evaluate it. The difference it, that fseek is a
bit slower, you get a message for 5 seconds at start-time and
this version does not contain all utilities.
If you register, you get:
- A program to modify the buffersizes. Large buffers make AFX work
a more speed (if you have the memory).
- A faster routine for fseek.
- It will start without delay.
- A free new version of PFXpak, Fortune and LHarc.
If you like to register, or if you have any questions, please write to
Thomas Quester
Lampenland 9
2050 Hamburg 80
Germany.