bool woodPileEmpty = false;
bool woodPileBusy = false;
int amountWoodInPile = 10;

Semafore mutexWoodInPile, mutexWoodPileEmpty;

void stoker(){
  while(1){
    if(!woodPileBusy){
      woodPileBusy = true;
      mutexWoodInPile.wait();
      if(amountWoodInPile > 0){
        amountWoodInPile -= 1; // Adding wood to fire
      } else {
        woodPileEmpty = true;
        woodPileBusy = false;
        mutexWoodInPile.signal();
        suspend();
      }
      woodPileBusy = false;
    }
  }
}



void stacker(){
  while(1){
    if(!woodPileBusy){
      woodPileBusy = true;
      mutexWoodPileEmpty.wait();
      if(woodPileEmpty){
        amountWoodInPile = 10; // Refilling woodpile
        resume(stoker);
        woodPileEmpty = false;
      }
      mutexWoodPileEmpty.signal();
      woodPileBusy = false;
    }
  }
The semaphores will protect the critical region, which is the IF statements, thus defendig it from data races.
}