Function myPinMode

wiringPi/pcf8574.c:44–58

 */

static void myPinMode (struct wiringPiNodeStruct *node, int pin, int mode)
{
  int bit, old ;

  bit  = 1 << ((pin - node->pinBase) & 7) ;

  old = node->data2 ;
  if (mode == OUTPUT)
    old &= (~bit) ;	// Write bit to 0
  else
    old |=   bit ;	// Write bit to 1

  wiringPiI2CWrite (node->fd, old) ;
  node->data2 = old ;
}