#/* *	UNIX shell * *	S. R. Bourne *	Bell Telephone Laboratories * *//* To use stack as temporary workspace across * possible storage allocation (eg name lookup) * a) get ptr from `relstak' * b) can now use `pushstak' * c) then reset with `setstak' * d) `absstak' gives real address if needed */#define		relstak()	(staktop-stakbot)#define		absstak(x)	(stakbot+Rcheat(x))#define		setstak(x)	(staktop=absstak(x))#define		pushstak(c)	(*staktop++=(c))#define		zerostak()	(*staktop=0)/* Used to address an item left on the top of * the stack (very temporary) */#define		curstak()	(staktop)/* `usestak' before `pushstak' then `fixstak' * These routines are safe against heap * being allocated. */#define		usestak()	{locstak();}/* for local use only since it hands * out a real address for the stack top */STKPTR		locstak();/* Will allocate the item being used and return its * address (safe now). */#define		fixstak()	endstak(staktop)/* For use after `locstak' to hand back * new stack top and then allocate item */STKPTR		endstak();/* Copy a string onto the stack and * allocate the space. */STKPTR		cpystak();/* Allocate given ammount of stack space */STKPTR		getstak();/* A chain of ptrs of stack blocks that * have become covered by heap allocation. * `tdystak' will return them to the heap. */BLKPTR		stakbsy;/* Base of the entire stack */STKPTR		stakbas;/* Top of entire stack */STKPTR		brkend;/* Base of current item */STKPTR		stakbot;/* Top of current item */STKPTR		staktop;/* Used with tdystak */STKPTR		savstak();