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Annotation of 40BSD/cmd/sh/stak.h, revision 1.1

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

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