[Open-graphics] Video interrupt enable/disable

[James Richard Tyrer]

Timothy Normand Miller wrote:
> On 5/5/07, James Richard Tyrer <tyrerj at acm.org> wrote:
> 
>> What your 'analysis' fails to consider is that, if shared, that the
>> 'sync' interrupt cannot be serviced until service of the 'service'
>> interrupt has completed to the point that the interrupt has been cleared
>>   (in hardware) and interrupt is enabled.  Also not considered is that
>> these two interrupts should have different priorities.
> 
> All of our interrupt conditions are latched and held until explicitly
> cleared.  If some other ISR were to get ahead of us, we would not miss
> our interrupt.

Yes, I know that.  The point I was trying to make was that the CPU can 
only do one thing at once and that a shared interrupt can not be 
serviced while the CPU is still servicing another of the interrupts that 
shares the hardware interrupt.  I don't know what the latency is -- you 
can't predict the latency on a non-RTS.

OTOH, if the 'sync' interrupt is a separate hardware interrupt, it will 
interrupt whatever is running and if it has a higher priority, the 
process it starts will run before the lower priority processes.

-- 
JRT