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Annotation of researchv10dc/cmd/sh/stak.h, revision 1.1

1.1     ! root        1: /*     @(#)stak.h      1.3     */
        !             2: /*
        !             3:  *     UNIX shell
        !             4:  *
        !             5:  *     Bell Telephone Laboratories
        !             6:  *
        !             7:  */
        !             8: 
        !             9: /* To use stack as temporary workspace across
        !            10:  * possible storage allocation (eg name lookup)
        !            11:  * a) get ptr from `relstak'
        !            12:  * b) can now use `pushstak'
        !            13:  * c) then reset with `setstak'
        !            14:  * d) `absstak' gives real address if needed
        !            15:  */
        !            16: #define                relstak()       (staktop-stakbot)
        !            17: #define                absstak(x)      (stakbot+Rcheat(x))
        !            18: #define                zerostak()      (*staktop=0)
        !            19: 
        !            20: /* Used to address an item left on the top of
        !            21:  * the stack (very temporary)
        !            22:  */
        !            23: #define                curstak()       (staktop)
        !            24: 
        !            25: /* `usestak' before `pushstak' then `fixstak'
        !            26:  * These routines are safe against heap
        !            27:  * being allocated.
        !            28:  */
        !            29: #define                usestak()       {locstak();}
        !            30: 
        !            31: /* for local use only since it hands
        !            32:  * out a real address for the stack top
        !            33:  */
        !            34: extern char            *locstak();
        !            35: 
        !            36: /* Will allocate the item being used and return its
        !            37:  * address (safe now).
        !            38:  */
        !            39: #define                fixstak()       endstak(staktop)
        !            40: 
        !            41: /* For use after `locstak' to hand back
        !            42:  * new stack top and then allocate item
        !            43:  */
        !            44: extern char            *endstak();
        !            45: 
        !            46: /* Copy a string onto the stack and
        !            47:  * allocate the space.
        !            48:  */
        !            49: extern char            *cpystak();
        !            50: 
        !            51: /* Allocate given ammount of stack space */
        !            52: extern char            *getstak();
        !            53: 
        !            54: /* A chain of ptrs of stack blocks that
        !            55:  * have become covered by heap allocation.
        !            56:  * `tdystak' will return them to the heap.
        !            57:  */
        !            58: extern struct blk      *stakbsy;
        !            59: 
        !            60: /* Base of the entire stack */
        !            61: extern char            *stakbas;
        !            62: 
        !            63: /* Top of entire stack */
        !            64: extern char            *brkend;
        !            65: 
        !            66: /* Base of current item */
        !            67: extern char            *stakbot;
        !            68: 
        !            69: /* Top of current item */
        !            70: extern char            *staktop;
        !            71: 
        !            72: /* Used with tdystak */
        !            73: extern char            *savstak();
        !            74: 
        !            75: #ifdef CRAY
        !            76: /* End of Memory */
        !            77: extern char *endcp;
        !            78: #endif

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