Hi,

I'm planning to develop something like DLL support for GO32V2 platform and I can't any decent documentation of these EXE files, can someone point me to website where can I find their structure and some additional information?

Anyway what has to be done to load EXE and find entry point? I know that I have to rellocate memory addresses and so on...

As far I remember there was something like this for TMT pascal, if someone already played with it and/or ported it to FPC please let me know :)

Thanks, Pavel Kanzelsberger

I'm planning to develop something like DLL support for GO32V2 platform and I can't any decent documentation of these EXE files, can someone point me to website where can I find their structure and some additional information?

Check the DJGPP site(s). Specially look for DXE support, which should already exist.

OK, thanks...

Regards, Pavel Kanzelsberger

I was checking FPC sources also and found DXE loader in RTL, DXE format is quite easy but it differs from EXE file, is there any way to compile DXE file with FPC or I have to write some kind of EXEtoDXE converter?

Regards, Pavel Kanzelsberger

Sorry for last e-mail, I found DXEGEN utility that generates .DXE file and can export one symbol from *.o file, anyway to work properly I have to get all DJGPP utils...

thanks again, Pavel Kanzelsberger

Well seems that i'll keep mailing here :-))

I tried DXEGEN and it fails due to unrecognized symbols (which are FPC specific) in .o file...
Is there any way how to remove them without editing .sw file?

C:\DJGPP>dxegen lib.dxe _ADD lib.o
ld -X -S -r -o dxe__tmp.o -Lc:/djgpp/lib lib.o -T dxe.ld Error: object contains unresolved external symbols (FPC_STACKCHECK) Error: object contains unresolved external symbols (INIT$$SYSTEM) Error: object contains unresolved external symbols (FPC_INITIALIZEUNITS) Error: object contains unresolved external symbols (FPC_DO_EXIT)

lib.pas
-----------------
funciont add (a,b:longint):longint;
 begin
 add:=a+b;
 end;
begin
end.
----------------

I think you could simply try to create an empty assembler file that defines those symbols for that, assemble

Something like

.file "dummydxe.as"

.text
.balign 16
.globl FPC_STACKCHECK :
ret
.balign 16

.globl INIT$$SYSTEM :
ret
.balign 16
.globl FPC_INITIALIZEUNITS :
ret
.balign 16
.globl FPC_DO_EXIT:
ret

Oh, that's not what I mean exactly...

That DXEGEN cannot convert .o file to .dxe because it doesn't understands these symbols, I want to find way how to remove them (or do anything else) so DXEGEN can successfully convert .o file...

Regards, Pavel Kanzelsberger

I mean do a

as bla.s -o bla.o

or so

And then add bla.o to the DXEGEN commandline. The symbols are added but empty/directly return.

Their functionality is reasonably unneeded, at least for this initial testing. (deal with unit initialisation)

Also note that you might get into problems with namemangling.

Define the entry procedure with

function add(a,b:longint):longint; external '_add'

and then use _add for "symbol" on the dxegen line below.

So something like

DXEGEN add.dxe _add add.o bla.o

(
DXE allows you to dynamically load code and data from a file and execute it. Limitations: you cannot do I/O (and some other functions) directly from a DXE loaded image. There is a single entry point (subroutine or data block returned).

There are two parts to DXE - the generator and the loader.

The DXE generator is a program with the usage:

C:\> dxegen output.dxe symbol input.o [input2.o ... -lgcc -lc]

output.dxe is the name you want to contain your dynamic load code. symbol is the procedure name (or data structure) you want a pointer to, remember to add the initial underscore for most symbols. The input.o is created with GCC from your source. Additional arguments on the command line (.o and .a files; or other ld options) are passed to ld to resolve references to build your code.

The loader only adds around 300 bytes to your image, and the prototype is found in <sys/dxe.h>:

  void *_dxe_load(char *filename);

It takes a single argument which is the file on disk containing the dynamic execution code. It returns a pointer to the symbol you specified at DXE generation time. See the documentation of dxe_load' in the library docs, for more details ("info libc alpha _dxe_load" from the DOS prompt). )

Ah okies! Going to give it a try, I will inform you :)

Ah okies! Going to give it a try, I will inform you :)

Ok!

function add(a,b:longint):longint; external '_add'

correction: external NAME '_add';