Driving a Bi-Stable solenoid

/* The pin numbers that the
*  driver boards are connected
*/
uint8_t pins[8] = {1,2,3,4,5,6,7,8};
uint32_t tick[4];

void turnOn(uint8_t num,uint8_t dir){
    tick[num]=millis();                       //store time switched on
    digitalWrite(pins[num*2],LOW);             //ensure both outputs are low
    digitalWrite(pins[num*2+1],LOW);
    if(dir==1){                                             
        digitalWrite(pins[num*2],HIGH);        //move CW
    }else{     
        digitalWrite(pins[num*2+1],HIGH);      //move CCW
    }
}

void turnOff(){
    for(uint8_t i=0;i<4;i++){
        if(tick[i]>0){                       //is this output on?
            if((millis()-tick)>=75){         //has it been on for 75mS?
                digitalWrite(pins[i*2],LOW);  //turn it off
                digitalWrite(pins[i*2+1],LOW);
                tick[i]=0;                   //clear time
            }
        }
    }
}