#include <stdio.h>

#define ACK -1
#define ABin -1
#define ACKRESP(x) -1

void async_loop() {
    // Every execution of this function will do one of the following:
    //  * Master the bus and send data across the parallel port
    //  * Be mastered and read data from the parallel port
    //  * Nothing
    static enum { S_IDLE, S_EXER, S_EXEI } state;
    typedef enum { C_DATA = 1, C_RESET = 0 } command_t;
    state = S_IDLE;
    while(1) {
        if(state == S_IDLE) {
            usleep(.1); // sleep while idle so we don't eat up all the CPU
            if(ACK) {
                // someone is trying to gain mastery of the bus
                ACKRESP(1); // tell them that it is okay to continue
                command = ABin;
            }
        }
        else if(state == S_EXER) {
            // we have been mastered... so start executing commands
            command = AB;
        }
    }
    return;
}

int main(int argc, char *argv[]) {
    return 0;
}