C language coroutine with switch-case

coroutine.c

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>

#define COROUTINE_START(line) switch (line) { case 0: 

#define WAIT_WHILE(condition) return __LINE__; case __LINE__: if (condition) return __LINE__;

#define COROUTINE_END default: return -1; }

int coroutine(int handle, 
     struct {
        int counter;
        int i;
    }* state)
{
    COROUTINE_START(handle);
    printf("Initialization\n");
    for (state->i = 0; state->i < 3; state->i++) {
        state->counter = 0;
        WAIT_WHILE(state->counter++ < 5);
        printf("Some code in the middle 1\n");
    }
    WAIT_WHILE(state->counter++ < 10);
    printf("Some code in the middle 2\n");
    WAIT_WHILE(state->counter++ < 15);
    printf("Finalization\n");
    COROUTINE_END;
}

int main(void)
{
    char state[256] = {0};
    int line = 0;
    while (line != -1)
    {
        line = coroutine(line, (void*)state);
        printf("%d\n", line);
    }
    
    return EXIT_SUCCESS;
}