.. include:: <mmlalias.txt>


Interrupt Handling
==================

.. topic:: Documentation

   * :doc:`../why-os/interrupts`
   * `Zephyr: Interrupt Service Routine APIs
     <https://docs.zephyrproject.org/latest/doxygen/html/group__isr__apis.html>`__

IRQs And ISRs
-------------

.. image:: sensor-irq.svg
   :scale: 60%
   :align: right

* Interrupt service routine (ISR): callback ``void(int irqnum)``
* Attached to an Interrupt request (IRQ) ``irqnum``
* Called *asynchronously* |longrightarrow| runs at the most
  inopportune time
* IRQ can safely be considered parallel (though varies per
  architecture)
* Main loop: power saving, ideally

Serving Interrupts
------------------

.. literalinclude:: code/sensor-irq.cpp
   :caption: :download:`code/sensor-irq.cpp`
   :language: c++

.. code-block:: console

   $ why-shell code/why-interrupt-sensor-irq 
   > irq 2
   irq #2: timestamp=196188342592226, value=97
   >