AWAIT/ASYNC for embedded programming in C.

async.c

#include <stdbool.h>
#include <stdint.h>


#define ASYNC(id_t) \
    static id_t ASYNC__=0; switch (ASYNC__) case 0: while(1)

#define YIELD() \
    do { ASYNC__=(__COUNTER__+2)/2; return; case (__COUNTER__+1)/2: ASYNC__=0; } while(0)

#define AWAIT(test) \
    do { while (!(test)) YIELD(); } while(0)


extern bool led;
extern bool pushbutton_on, pushbutton_off, pushbutton_toggle;


void example()
{
    ASYNC(uint8_t)
    {
        AWAIT(!pushbutton_on && !pushbutton_off && !pushbutton_toggle);

        AWAIT(pushbutton_on || pushbutton_off || pushbutton_toggle);

        if (pushbutton_on && !pushbutton_off && !pushbutton_toggle)
            led = true;

        else if (pushbutton_off && !pushbutton_on && !pushbutton_toggle)
            led = false;

        else if (pushbutton_toggle && !pushbutton_on && !pushbutton_off)
            led = !led;
    }
}