[lwip-users] FromISR port abstraction layer (was: Help with LwIP Modem)

[address@hidden]

Jeff Barlow wrote:
> [..] It seems fairly
> obvious to me though that inserting extra code in the ISR path that
> inspect some globals only to figure out that it is indeed in an ISR will
> have an adverse effect on latency.

I might be picky here, but using C instead of assembler tends o have an 
advers effect on latency, too. ;-)

What I mean is personally, I don' think it's good design to expose the 
ISR/non-ISR fact accross layers of the code that possibly have nothing 
to do with that knowledge.

Keeping my private view aside, is there a requirement to add "fromISR" 
code in the port layer? If so, now would be the best time!

> For some of us this makes the difference between a
> working system and one that almost works.

To be hones, I still can't believe ~3 cycles (load a global "bool", 
test, jump) make a difference here, compared to running the task 
scheduler when leaving the interrupt... Additionally, e.g. Cortex-M 
systems wouldn't even really need the info when the scheduler is run 
from lowest-prio interrupt level anyway...

Simon