[Lazarus] Newbie, porting class to FPC but get procedure assignment error

Bo Berglund bo.berglund at gmail.com
Tue Jun 23 17:51:42 CEST 2015

On Tue, 23 Jun 2015 12:07:05 +0000, Mark Morgan Lloyd
<markMLl.lazarus at telemetry.co.uk> wrote:

>Bo Berglund wrote:
>> On Mon, 22 Jun 2015 16:43:31 -0300, luiz americo pereira camara
>> <luizmed at oi.com.br> wrote:
>>> In the breakpoint do a step into (f7) and ser the exact line that crashes
>>> Luiz
>> In the pas unit this is the exact line that crashes:
>> returnVal := RNBOsproFormatPacket (ApiPacket, RB_SPRO_APIPACKET_SIZE);
>> This is the first call into the drive via the converted obj file.
>> Must be something in error in the conversion.
>Or in the declaration of the parameter types.

Note that what I am trying to accomplish is porting an application
from Delphi to Lazarus where the dongle handling is by way of an
interface unit (spromeps.pas) and an include file (spromeps.obj) where
the implementation of the API into the SuperPro driver is done.

In Delphi the obj file is used as follows:


It has worked just fine since roundabout 2002 in all the Delphi
versions we have used including XE5.
The spromeps.pas file declares all the needed functions which we need
to use in the driver and calls them as externals via the obj file.

Unfortunately Lazarus/FPC does not handle the obj file so this thread
is really about ways to get around that by converting the obj file to
coff (or elf) that FPC can handle.
I got tipped off about a tool thta can do this and downloaded objconf
from here:

The problem is most likely in the conversion because even the smallest
test application throws an exception on the very first call into the
driver, the initialization of the Api data interface array.

The function call shown above is the last in a chain starting in the
main application by the method Dongle.InitKey. Everything up to this
call seems OK on inspection but the actual call to the driver via the
converted obj file (now a coff file) fails.

Since the obj file works in Delphi with such disparate versions as
Delphi 5 up to Delphi XE5 it cannot be a compiler incompatibility
problem, really.
It MUST be the conversion using objconv, which is somehow improperly
set up for the task. But it is hard to understand how to set it up
since I have no experience in such low-level programming in Windows.

This is where I am now:
No matter what I try there are exceptions generated...  :(
It would have been nice if FPC could accept linking with a regular OBJ
file so I did not have to convert it.

Bo Berglund
Developer in Sweden

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