It&#x27;s missing this link, which I previously thought was &quot;the&quot; co-routine de-facto standard for C before seeing all those other links: <a href="http:&#x2F;&#x2F;www.chiark.greenend.org.uk&#x2F;~sgtatham&#x2F;coroutines.html" rel="nofollow">http:&#x2F;&#x2F;www.chiark.greenend.org.uk&#x2F;~sgtatham&#x2F;coroutines.html</a><p>There&#x27;s a link to the .h file near the bottom of the page.<p>That technique is what&#x27;s used in protothreads and Contiki OS.