text: #ifndef	_STDDEF
  typedef	int		ptrdiff_t;	/* result type of pointer difference */
  typedef	unsigned	size_t;		/* type yielded by sizeof */
  #define	_STDDEF
  #define	offsetof(ty, mem)	((int)&(((ty *)0)->mem))
  #endif	_STDDEF
  
  #ifndef	NULL
  #define	NULL	((void *)0)
  #endif	NULL
  
  extern int	errno;			/* system error number */
  
  