I am programming with FreePascal and Lazarus towards a Raspberry Pi2 target platform. Doing so on the RPi2 itself is possible and basically works fine, except that the system is a bit sluggish at times and there are other inconveniences as well.
So I moved to a Linux Mint 17.3 Mate system in a virtual computer (VMWare) on my Windows7 PC instead.

Most of what I am doing concerns non-hardware dependent things and works fine as far as I can see.
But there is one snag, and this is the GPIO handling where obviously the GPIO access is not possible on a PC platform...

So I need to put some kind of conditional into my code to redirect the GPIO calls to some simulator I will have to build. (I am assuming that there is no such thing available already of course).

So I would like to know how I can create a conditional that uses the real GPIO if the build is done on the RPi2 itself and for the simulator otherwise.
Something like:

uses
...

  {$IFDEF RPi2Hardware}
  PiGpio,
  {ELSE}
  PiGpioSim,
  {$ENDIF}

Then I could create a PiGpioSim unit as a simulator that defines the same object class but does not target the actual hardware on RPi2 but some other mechanism that I can monitor while debugging in the development PC.

Is there something like "RPi2Hardware" already set up that can be used to check for this?

Bo Berglund wrote

I am programming with FreePascal and Lazarus towards a Raspberry Pi2 target platform. Doing so on the RPi2 itself is possible and basically works fine, except that the system is a bit sluggish at times

Apologies for OT, but probably relevant to anybody using RPi. There's a known memory leak in irqbalance which will drive it into thrashing, see

https://github.com/Irqbalance/irqbalance/issues/5

for patch.

Hi Bo,

From: Bo Berglund

<snip>

I am programming with FreePascal and Lazarus towards a Raspberry Pi2

Another way (which might be easier?) is to look at the GPIO driver code (API) on the Raspberry and write a "fake driver" (.so file?) on the Linux system with the same name, API etc. of the Raspberry GPIO driver (I assume that there is a driver, so forgive me if I am wrong). Since you want to build a simulator in any case, this might be a better option that will not require you to do anything funny in your actual application code?

Regards,
Chavoux
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I found that {$ifdef CPUARMHF} can be used as a switch for my purposes.

I looked inside the PiGpio unit to see how it interacts and this is what I found:

function TIoDriver.MapIo: boolean;
begin
 Result := True;
 {$IFDEF RPi2}
   fd := fpopen('/dev/gpiomem', O_RdWr or O_Sync); // Open the master
/dev/memory device
 {$ELSE}
   fd := fpopen('/dev/mem', O_RdWr or O_Sync); // Open the master
/dev/memory device
 {$ENDIF}
  if fd < 0 then
  begin
    Result := False; // unsuccessful memory mapping
  end;
 //
end;

So there is a "master memory device" /dev/gpiomem, whatever that is... I looked at the location in a terminal and found this:

pi at rpi2-jessie2:/dev $ ls -ls g*
0 crw-rw---- 1 root gpio 244, 0 Feb 25 07:40 gpiomem

So there seems to be no .so file here at least...

And I have no clue whatever regarding what to do to create a driver...