API to convert priorities to/from POSIX from/to Classic?

[Gedare Bloom]

I can get on board with extending the classic API to include
converters to/from posix priorities directly.. this makes good enough
sense to me.

On Mon, Jul 30, 2018 at 2:30 PM, Joel Sherrill <joel at rtems.org> wrote:
>
>
> On Mon, Jul 30, 2018 at 1:03 PM, Sebastian Huber
> <sebastian.huber at embedded-brains.de> wrote:
>>
>> ----- Am 30. Jul 2018 um 18:29 schrieb Gedare Bloom gedare at rtems.org:
>>
>> > On Mon, Jul 30, 2018 at 11:23 AM, Joel Sherrill <joel at rtems.org> wrote:
>> >>
>> >>
>> >> On Mon, Jul 30, 2018 at 7:43 AM, Sebastian Huber
>> >> <sebastian.huber at embedded-brains.de> wrote:
>> >>>
>> >>> On 30/07/18 14:25, Joel Sherrill wrote:
>> >>>>
>> >>>>
>> >>>>
>> >>>> On Mon, Jul 30, 2018, 6:26 AM Sebastian Huber
>> >>>> <sebastian.huber at embedded-brains.de
>> >>>> <mailto:sebastian.huber at embedded-brains.de>> wrote:
>> >>>>
>> >>>>     Hello,
>> >>>>
>> >>>>     is there a standard API to convert priorities to/from POSIX
>> >>>> from/to
>> >>>>     Classic? If not, I think we should add something.
>> >>>>
>> >>>>
>> >>>> There is not a public API for this.  There are some internal helpers
>> >>>
>> >>>
>> >>> Do you know the name of the helpers?
>> >>
>> >>
>> >> I was thinking of the _RTEMS_Priority_To_Core,
>> >> _RTEMS_Priority_From_core, and the similar
>> >> POSIX helper.
>> >>
>> >> These are probably useful to some users. No real
>> >> cost to applications that don't use them.
>> >>
>> >
>> > These convert between the core kernel notion of priority and the api.
>> > I see no problem to add some wrappers like
>> >
>> > rtems_posix_priority_to_core() and from_core(), and
>> > rtems_priority_to_core(), and from_core().
>> >
>> > A user then could convert between the two APIs themselves if they need,
>> > like
>> > rtems_priority_from_core( rtems_posix_priority_to_core(p) );
>> >
>> > I would not introduce any conversion between classic and posix
>> > priorities directly. It is violation of the API independence.
>>
>> I don't like the idea to expose an internal priority thing to the user. We
>> would have to create an API representation of something scheduler-specific.
>>
>> I propose:
>>
>> scheduler_id == RTEMS_SELF == scheduler of executing thread
>>
>> rtems_status_code rtems_task_priority_posix_to_classic(rtems_id
>> scheduler_id, int posix_priority, rtems_task_priority *classic_priority)
>> rtems_status_code rtems_task_priority_classic_to_posix(rtems_id
>> scheduler_id, rtems_task_priority classic_priority, int *posix_priority)
>
>
>
> For the simplest case of current scheduler, what does a call look like?
>
> And honestly, I wouldn't be opposed to something like this if it has a use
> case:
>
> rtems_task_priority rtems_get_self_priority(void)
>
> The Classic API (e.g. RTEID/ORKID) reflects a period in API programming
> where
> you wanted a small API set. Accessors were not separated out. Methods to
> simply get some information or state of an object were not included.
>