Switch-case coroutine

#include <stdio.h>

#include <stdlib.h>

typedef struct {int phase; void* data;} HCOROUTINE;

#define COROUTINE(name, ...) name(HCOROUTINE* __coroutine_phase, ##__VA_ARGS__)

#define COBEGIN(args) struct { args }** __coroutine_dataref=(typeof(__coroutine_dataref))&__coroutine_phase->data;\

switch(__coroutine_phase->phase){case 0: do{*__coroutine_dataref=malloc(sizeof(**__coroutine_dataref));}while(0);

#define STATE (**__coroutine_dataref)

#define YIELD(x) do{__coroutine_phase->phase=__LINE__; return x;}while(0); case __LINE__:{}

#define COEND };__coroutine_phase->phase=-1; free(*__coroutine_dataref);

#define NEXT(st, coro, ...) (coro(&st, ##__VA_ARGS__))

#define ENDED(x) ((x.phase)==-1)

typedef int COROUTINE_PHASE;

int COROUTINE(hello){

COBEGIN(int a;)

STATE.a=1;

printf("Hello, %d, for the first time!\n", STATE.a);

STATE.a=2;

YIELD(114)

printf("Hello, %d, for the second time!\n", STATE.a);

STATE.a=3;

YIELD(514)

printf("Hello, %d, for the last time!\n", STATE.a);

YIELD(810)

COEND

return 893;

}

int main(void) {

printf("Hello World!\n");

HCOROUTINE st={};

while(!ENDED(st)){

int ret=NEXT(st, hello);

printf("Coroutine yielded %d\n", ret);

}

return 0;

}