bsp_delay.... Question

[Andrei Chichak]

Alright, I'm going to have to advocate for the little guy.

At 16Mhz, I would have, at best, 16 instructions at a microsecond.

A millisecond based delay would be doable using a timer. I could see crafting a loop for a microsecond delay, but nanosecond would be a summer fantasy. 

Andrei


On 2011-April-25, at 12:49 PM, Joel Sherrill wrote:

> On 04/25/2011 11:49 AM, Thomas Doerfler wrote:
>> Joel,
>> 
>> without looking into the existing implementations: I would prefer to
>> have nanoseconds as a base unit. If we think about systems in the 1GHz
>> range, having a resolution of 1000 CPU clocks seems a bit outworn to me.
>> 
>> 
> I agree with you Thomas but the existing implementations appear
> to be in microseconds.  The common name is rtems_bsp_delay().
> 
> I wouldn't be opposed to adding an rtems_bsp_delay_nanoseconds()
> to the set.
> 
> Jennifer and I were just looking at this.  The non-uniform nature
> of this across the BSPs is confusing.
> 
> --joel
>> wkr,
>> 
>> Thomas.
>> 
>> Am 25.04.2011 18:02, Joel Sherrill wrote:
>>> Hi,
>>> 
>>> Some BSPs have a bsp_delay method.  This is
>>> a short duration spinner.  We think it is in
>>> microsecond units but have no idea for sure
>>> and it could vary by BSP.
>>> 
>>> Jennifer and I would like to formalize the
>>> definition of this.  And standardize it across
>>> BSPs.  So if it is available, it is safer to
>>> use. Questions are
>>> 
>>> + OK to make a standard BSP method?
>>> + Microseconds unit?
>>> 
>>> If it is not available, what should the stub do?
>>> 
>>> Should we have bsp_delay_usecs() and bsp_delay_nsecs?
>>> 
>>> Comments appreciated!  Please
>>> 
>> 
> 
> 
> -- 
> Joel Sherrill, Ph.D.             Director of Research&  Development
> joel.sherrill at OARcorp.com        On-Line Applications Research
> Ask me about RTEMS: a free RTOS  Huntsville AL 35805
>  Support Available             (256) 722-9985
> 
> 
> _______________________________________________
> rtems-users mailing list
> rtems-users at rtems.org
> http://www.rtems.org/mailman/listinfo/rtems-users
>