#define POW	75
#define TURN90	100

mutex moveMutex;


void turn_right(int time)   // �E��]
{
    Off(OUT_A);
    OnFwd(OUT_C, POW);
    Wait(time);
}

void turn_left(int time)    // ����]
{
    OnFwd(OUT_A, POW);
    Off(OUT_C);
    Wait(time);
}

task line_trace()
{
    while(true){
        if(Sensor(IN_3) > 40){
            Acquire(moveMutex);
            turn_right(1);
            Release(moveMutex);
        }else{
            Acquire(moveMutex);
            turn_left(1);
            Release(moveMutex);
        }
    }
}


task collision_avoidance()
{

    while(true){
        if(SensorUS(IN_4) < 25){
            Acquire(moveMutex);
            turn_right(TURN90);
            Release(moveMutex);
        }
    }
}


task main()
{
    SetSensorLight(IN_3);
    SetSensorLowspeed(IN_4);
    Precedes(line_trace, collision_avoidance);
}