This is the mail archive of the
ecos-discuss@sourceware.org
mailing list for the eCos project.
Re: CYG_ISR_CALL_DSR vs CYG_ISR_HANDLED
- From: Gary Thomas <gary at mlbassoc dot com>
- To: osv <osv at javad dot com>
- Cc: eCos Discussion <ecos-discuss at ecos dot sourceware dot org>
- Date: Fri, 18 Nov 2005 07:12:18 -0700
- Subject: Re: [ECOS] CYG_ISR_CALL_DSR vs CYG_ISR_HANDLED
- References: <87veyqgipi.fsf@javad.com>
On Fri, 2005-11-18 at 16:59 +0300, osv wrote:
> Hello,
>
> In the eCos reference manual one can read:
>
> The return value of an ISR is normally one of CYG_ISR_CALL_DSR or
> CYG_ISR_HANDLED. The former indicates that further processing is
> required at DSR level, and the interrupt handler’s DSR will be run as
> soon as possible. The latter indicates that the interrupt has been
> fully handled and no further effort is required.
This is poorly worded I think.
>
> However, the eCos internal clock isr (Cyg_RealTimeClock::isr()) returns
> as follows:
>
> return Cyg_Interrupt::CALL_DSR|Cyg_Interrupt::HANDLED;
>
> that seems to contradict with the description above. What is the truth
> about isr handler return codes?
CYG_ISR_HANDLED says that the ISR actually did something about the
interrupt. It's used by chained interrupts to determine if another
ISR (which shares the same interrupt) should be run.
CYG_ISR_CALL_DSR indicates that the DSR which corresponds to this ISR
should be run.
These are bit values which can be successfully or'ed together to achieve
the desired result.
--
------------------------------------------------------------
Gary Thomas | Consulting for the
MLB Associates | Embedded world
------------------------------------------------------------
--
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss