[Xenomai-help] How to avoid a tight real time loop

[Daniele Nicolodi <daniele@domain.hid>]

Hello. In my application I need to read data from an ADC card in blocks
of a given number of samples. For efficiency I'm using an mmapped buffer
to exchange data with the ADC driver. I'm setting up the acquisition,
and then calling a loop like this:

unsigned int required = <compute required number of bytes>;
unsigned int read = 0;
while (1) {
  while (read < required) {
    read = a4l_pool(...);
  }
  process(buffer, ...);
}

However if I run this loop in a real time thread the tight while loop is
an obvious cpu hog: the watchdog kicks in and kills the thread.

There is not an analogy API that can be used to require a certain amount
of data to the ADC driver. How can I code this loop to let other
processes to run?

Thanks. Cheers,
-- 
Daniele