#define barrier() __asm__ volatile ("lwsync")
  

  volatile T* pInst = 0;
  

  T *GetInstance()
  

  {
  

  if( !pInst )
  

  {
  

  lock();
  

  if( !pInst )
  

  {
  

  T* tmp = new T;
  

  barrier();
  

  pInst = tmp;
  

  }
  

  unlock();
  

  }
  

  

  return pInst;
  

  }