Line 17 & 20

main.c

static struct coro {
	struct coro *next;
	jmp_buf state;
} first, *running = &first, *idle;


static void *pass(coro me, void *arg) {
	static void *saved;
	saved = arg;
	if(!setjmp(me->state))
		longjmp(running->state, 1);
	return(saved);
}


void coroutine_main(void *ret) {
	void *(*fun)(void *arg); // Function Pointer, ok...
	struct coro me;
	push(&idle, &me);
	fun = pass(&me, ret); // Wait...what?
	if(!setjmp(running->state))
		coroutine_start();
	for(;;) {
		ret = fun(yield(&me));
		push(&idle, pop(&running));
		fun = pass(&me, ret);
	}
}