register pointer  ptr;  if ((long)amount <= 0) return NULL;
pointer ptr;
Xalloc(unsigned long amount){    register pointer  ptr;	    if ((long)amount <= 0)	return NULL;    /* aligned extra on long word boundary */    amount = (amount + (sizeof(long) - 1)) & ~(sizeof(long) - 1);#ifdef MEMBUG    if (!Must_have_memory && Memory_fail &&	((random() % MEM_FAIL_SCALE) < Memory_fail))	return NULL;#endif    if ((ptr = (pointer)malloc(amount))) {	return ptr;    }    if (Must_have_memory)	FatalError("Out of memory");    return NULL;}