if(TimerA != 0)
{
   TimerA--;
}
else
{
   TimerAExpired = TRUE;
}

if(TimerB != 0)
{
   TimerB--;
}
else
{
   TimerBExpired = TRUE;
}

if(TimerC != 0)
{
   TimerC=- /* sic */;
}
else
{
   TimerCExpired = TRUE;
}