duff's device

duff.c

#include <stdio.h>

#define coro(b) \
  static int __cont = 0; \
  switch (__cont) { case 0:; \
  b }

#define yield(v) \
  do { \
    __cont = __LINE__; \
    return v; case __LINE__:; \
  } while (0)

int
odd() {
  static int i = 1;
  coro({
    while (1) {
      yield(i);
      i += 2;
    }
  })
  return 0;
}

int
main(void) {
  for (int i = 0; i < 10; ++i) printf("%d\n", odd());
}

gistfile1.txt

1
3
5
7
9
11
13
15
17
19

that's so horrible. :)

you love it hahaha