Coroutines in C

coro.c

//
// coro.c
//
// Based on a a Duff's device
// https://pusher.com/sessions/meetup/the-realtime-guild/realtime-stream-processing-with-coroutines
//

/*
 * Coroutine.
 */

int
coro() {
  static int i, s = 0;
  switch (s) {
    case 0:
      for (i = 0; ; i++) {
        if (!s) s = 1;
        return i;
        case 1:;
      }
  }
}

/*
 * Run program.
 */

int
main() {
  printf("%d\n", coro()); // 0
  printf("%d\n", coro()); // 1
  printf("%d\n", coro()); // 2
}