Configuring GCC with FreeRTOS and OpenOCD

Question

I'm pretty sure this is possible but I'm not sure how to go about it. I'm very new to building with GCC in general and I have never used FreeRTOS, but I'd like to try getting the OS up and running on a TI ARM Cortex MCU but with a slight twist: I'd like to get it up and running with Pascal. I'm curious:

• Is this even possible to get work? If not, the next issues are kind of moot points.
• From my Delphi days, I vaguely recall the ability to access functions in C libraries. I'm wondering if I would have access to the C routines in FreeRTOS.
• If I use the GCC version (preferable) would I be able to debug using OpenOCD on the target? I'm not quite sure how debug symbols work and if it's more or less language agnostic (hopefully, in this case).
• As kind of a bonus question a bit outside the scope of the original query, can I simulate FreeRTOS on an x86 processor (e.g. my development PC) for easier debugging during development? (With a Pascal program, of course..)

I haven't found any documentation on achieving this, so hopefully someone here can shed some light! Any resources would be most helpful. Like I said, I'm very new to this kind of development. I'm also open to suggestions if you think there is a better alternative.

FYI, my preferred host configuration would be something similar to:

• Linux (Ubuntu/Debian)
• Eclipse IDE for development, unit testing, and hopefully simulation / debugging
• OpenOCD for target debugging
• GNU Pascal + FreeRTOS on target

Answer 1

There is already an example for FreeRTOS/GCC/OpenOCD on a TI Cortex-M3 (was Luminary Micro Cortex-M3). Be aware though that this is a really old example and both the Eclipse and OpenOCD versions used are out of date.

Although there is an Eclipse project provided, the project is configured as a standard make (as opposed to a managed make) project, so there is a standard makefile that can be just as easily executed from the command line as from within Eclipse.

http://www.freertos.org/portLM3Sxxxx_Eclipse.html

Answer 2

Both GNU Pascal and Free Pascal support linking to C (gcc) and ARM, as well as calling pascal code from C etc. Writing a header and declaring the prototypes with cdecl is all there is to it.

Macros are a bit bigger problem. Usually I just rewrite them to inline functions (what they should have been anyway). Except for the macro/header issue, the problems are more compiler specific functionality (which you also would have a problem with when porting from one C compiler to the next)

If you prefer TP/Delphi dialect, Free Pascal is the better choice.

I run my old Delphi code fine on my sheevaplug.

Answer 3

FreeRTOS is C source code, so like you say you would have to have some mechanism for linking C with your Pascal programs. Also, FreeRTOS relies on certain registers to be used for things like passing a parameter into a task (as a hypothetical example, the task might always expect the parameter to be in register R0) so you would have to ensure the ABI for the C compiler and the Pascal compiler was the same - or have your task entry in C then have it call a Pascal function (very nasty). Then there is the issue of interrupts, calling inline macros, etc. I would say this would be extremely difficult to achieve.