This example code shows how to make a plugin system using the LoadSeg()
funtion. Other methods use the library system, which I think is a misuse
of the system for shared libraries.

This demo shows lots of methods used in development of the XAD library
system, so if something is unclear, read the docs of XAD.

Supported features:
- Plugins may be internal and external. This allows compact executables
  with plugin support (but does not require external plugins).
- Internal plugins get an unique ID and can be overwritten by external
  plugins.
- Multiple plugins in one file. This allows to reuse common code.
- Enforces version strings for the plugins to make the C:Version
  command work.
- Versioning system to allow up- and downwards compatibility.

How to compile:
The file master.c is a normal C source code and can be compiled with
any compiler without problems.

The plugin files creation consist of three steps:
a) The file exterheader.c is compiled to an object file. To get this
   file the linking option must be turned of and data modell must be
   large.
b) The plugin source must be compiled without linking and in large
   data mode as well.
   NOTE: Using standard ANSI-C I/O-functions is not possible normally,
   as no startup-code is used (this is a plugin!). Also DOSBase or
   any other library base is not opened automatically. Either the
   master supplies these, or the libraries must be opened in the plugin
   from scratch (using AbsExecBase as starting point).
c) Linking the two files together, where the extheader object is
   the first one and the plugin file the second.

Makefiles are supplied for SAS-C and VBCC. Both files will work with
GNU make and smake (except clean and cleanall targets, which only work
with smake).

NOTE: The functions in this example use the stack for argument passing.
When creating public plugins it may be better to use registers.

If you can submit adjustments and fixes feel free to send these. Feel
free to use this source for own projects.

History:
  1.0  first version
  1.1  fixed for GCC, Thanks Gunther Nikl and Daniel Allsopp for help

Please contact me:

*********************************************************************
* snail-mail:                  * e-mail:                            *
*   Dirk Stoecker              *   stoecker@epost.de                *
*   Geschwister-Scholl-Str. 10 *   dirk@dstoecker.de                *
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*   GERMANY                    *   http://www.dstoecker.de/         *
* phone:                       * pgp key:                           *
*   GERMANY +49 (0)3594/706666 *   get from WWW pages or keyservers *
*********************************************************************

Following is my PGP signature for the corresponding LhA-File.
Use ' pgpv PluginDemo.readme -o PluginDemo.lha ' to check it.
Key fingerprint: B9 F2 3A 1A 29 02 75 16  6A C6 5B 7D 5E F6 16 CF.
All my releases after April 2001 have a PGP signature with this key.
Be alarmed if signature is missing or wrong.

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 PERMSSN    UID  GID    PACKED    SIZE  RATIO     CRC       STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]                 1342    1686  79.6% -lh5- 93ac Nov 30  2003 PluginDemo.info
[generic]                 1898    2752  69.0% -lh5- ca1e Nov 30  2003 PluginDemo/example/master
[generic]                  274     432  63.4% -lh5- 5c98 Nov 30  2003 PluginDemo/example/plugins/plugin_2
[generic]                  196     284  69.0% -lh5- 66e7 Nov 30  2003 PluginDemo/example/plugins/plugin_hello
[generic]                  476     974  48.9% -lh5- 21b3 Nov 30  2003 PluginDemo/extheader.c
[generic]                  313     848  36.9% -lh5- 30a6 Nov 30  2003 PluginDemo/makefile.gcc
[generic]                 1977    5364  36.9% -lh5- c9c4 Nov 30  2003 PluginDemo/master.c
[generic]                  859    2138  40.2% -lh5- 36e3 Nov 30  2003 PluginDemo/plugin.h
[generic]                  515    1152  44.7% -lh5- 11ec Nov 30  2003 PluginDemo/plugin_2.c
[generic]                  449     822  54.6% -lh5- 6d18 Nov 30  2003 PluginDemo/plugin_hello.c
[generic]                 1324    2891  45.8% -lh5- 48fa Nov 30  2003 PluginDemo/PluginDemo.readme
[generic]                    0       0 ****** -lh0- 0000 Nov 30  2003 PluginDemo/plugins/
[generic]                  336     905  37.1% -lh5- 5d41 Nov 30  2003 PluginDemo/SMakeFile
[generic]                  287     811  35.4% -lh5- e216 Nov 30  2003 PluginDemo/vmakefile
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total        14 files   10246   21059  48.7%            Dec  7  2003