Adding TerminateTask(); in the examples provided

[chowned]

This is a minor thing, but I added at the end of each task in the examples provided for Arduinos a simple "TerminateTask();". Arduino manages to still run without this code even if it is not beautiful, but this is enforcing a bad programming habit.

This is something similar as "fclose" for files.

Codes were tested and were running like expected. Just it drives better new programmers.

[mbriday]

Hi, Thanks. In fact, the TerminateTask() is not required in Trampoline, as the tpl_init_context function inserts the TerminateTask() call in the stack (in machine/avd/tpl_machine.c) regards, Mik

[jlbirccyn]

Thanks a lot @chowned.

I correct my colleague a bit. 🙂

Not calling TerminateTask() is an error according to AUTOSAR requirement SWS_Os_00069 and section 4.7 of OSEK/VDX Operating System.

Trampoline complies with the AUTOSAR standard. Therefore it meets the following requirements:

• [SWS_Os_00052] If a task returns from its entry function without making a TerminateTask() or ChainTask() call, the Operating System module shall terminate the task (and call the PostTaskHook() if configured).
• [SWS_Os_00069] If a task returns from its entry function without making a TerminateTask() or ChainTask() call AND the error hook is configured, the Operating System module shall call the ErrorHook() (this is done regardless of whether the task causes other errors, e.g. E_OS_RESOURCE) with status E_OS_MISSINGEND before the task leaves the RUNNING state.
• [SWS_Os_00070] If a task returns from the entry function without making a TerminateTask() or ChainTask() call and still holds OSEK Resources, the Operating System module shall release them.
• [SWS_Os_00239] If a task returns from the entry function without making a TerminateTask() or ChainTask() call and interrupts are still disabled, the Operating System module shall enable them.

This explains why Trampoline supports omitting TerminateTask(). The purpose of these AUTOSAR requirements is to avoid unpredictable behavior.

From the implementation point of view, the return address of a task is the CallTerminateTask function (this is the case for the AVR port). CallTerminateTask performs the following operations:

• If interrupts are disabled, they are enabled (SWS_Os_00239);
• If ressource(s) are held, they are released (SWS_Os_00070);
• If error hook is configured, it is called with E_OS_MISSINGEND status (SWS_Os_00069);
• Call TerminateTask() (SWS_Os_00052).

Best regards.

Jean-Luc