This is EasyLibs 1.0, a package of tools and sources to create a shared
library.
Programming shared libraries is often somewhat nasty: You have to create
the library header which is done in Assembler (until now :-), you
have to maintain FD files, prototypes, pragmas, autodocs and all that
kind of stuff. EasyLibs is my try to do this with less work, even more:
Most parts are created automatically.
EasyLibs consists of the following parts:
- LibHeader.c 1.0, a complete and universal library header which can
be used for any type of library you want. Never again edit the
header, just change some preprocessor symbols! LibHeader.c is
written in C completely.
LibHeader.c, however, can be used by the Dice compiler only. To be
precise: You need a possibility to put the resident structure into
the code segment. Dice allows this by declaring the struct as
"const".
- Xtract 1.1, a small tool which extracts prototypes, FD files and
Autodocs from source files. (I personally prefer "autodoc" from the
NDU for the latter purpose, however.)
- fd2pragma 2.2, a program which can read FD files and convert them
into either pragma files for different compilers (Aztec, SAS, Dice,
Maxon), LVO files to be read by assemblers or function tables to
be read by LibHeader.c.
- HelloWorld.library 40.1, a small shared library which shows how to
use these tools.
Some notes on using LibHeader.c. (Some of them hold true for any library
regardless of using LibHeader.c)
- You might well use global data; either initialized or uninitialized,
but keep in mind that this is a *shared* library: Your data will be
shared by different tasks. In general one uses only things like
library base pointers or similar stuff in global data.
- The startup code of LibHeader.c does *not* zero the BSS segment.
Unlike usual C programming you can not expect that variables are
0 or NULL, respectively, except if you force this by using something
like
struct IntuitionBase *IntuitionBase = NULL;
- It is possible to use the small data model. However, you need to
setup the a4 register when entering the library. Best way to ensure
this is declaring all library functions which are visible to the
outside world as SAVEDS. (See HelloWorldLib.c)
- Dice has the peculiarity to precede function names with an '@' instead
of the usual '_', if they expect arguments in registers. If they don't
expect arguments, however, Dice will use the '_' too. So always let
your library functions expect at least one argument, (The library base
pointer in a6 is a good choice.) even if you don't need it. The linker
will claim missing symbols otherwise.
EasyLibs is in the public domain, use it as you want, but WITHOUT ANY
WARRANTY. Bugs, suggestions, notes and beer bottles to
Jochen Wiedmann
Am Eisteich 9
72555 Metzingen
Germany
Phone: 07123 / 14881
Internet: wiedmann@zdv.uni-tuebingen.de
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