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Annotation of 42BSD/bin/sh/stak.h, revision 1.1

1.1     ! root        1: /*     stak.h  4.1     82/05/07        */
        !             2: 
        !             3: #
        !             4: /*
        !             5:  *     UNIX shell
        !             6:  *
        !             7:  *     S. R. Bourne
        !             8:  *     Bell Telephone Laboratories
        !             9:  *
        !            10:  */
        !            11: 
        !            12: /* To use stack as temporary workspace across
        !            13:  * possible storage allocation (eg name lookup)
        !            14:  * a) get ptr from `relstak'
        !            15:  * b) can now use `pushstak'
        !            16:  * c) then reset with `setstak'
        !            17:  * d) `absstak' gives real address if needed
        !            18:  */
        !            19: #define                relstak()       (staktop-stakbot)
        !            20: #define                absstak(x)      (stakbot+Rcheat(x))
        !            21: #define                setstak(x)      (staktop=absstak(x))
        !            22: #define                pushstak(c)     (*staktop++=(c))
        !            23: #define                zerostak()      (*staktop=0)
        !            24: 
        !            25: /* Used to address an item left on the top of
        !            26:  * the stack (very temporary)
        !            27:  */
        !            28: #define                curstak()       (staktop)
        !            29: 
        !            30: /* `usestak' before `pushstak' then `fixstak'
        !            31:  * These routines are safe against heap
        !            32:  * being allocated.
        !            33:  */
        !            34: #define                usestak()       {locstak();}
        !            35: 
        !            36: /* for local use only since it hands
        !            37:  * out a real address for the stack top
        !            38:  */
        !            39: STKPTR         locstak();
        !            40: 
        !            41: /* Will allocate the item being used and return its
        !            42:  * address (safe now).
        !            43:  */
        !            44: #define                fixstak()       endstak(staktop)
        !            45: 
        !            46: /* For use after `locstak' to hand back
        !            47:  * new stack top and then allocate item
        !            48:  */
        !            49: STKPTR         endstak();
        !            50: 
        !            51: /* Copy a string onto the stack and
        !            52:  * allocate the space.
        !            53:  */
        !            54: STKPTR         cpystak();
        !            55: 
        !            56: /* Allocate given ammount of stack space */
        !            57: STKPTR         getstak();
        !            58: 
        !            59: /* A chain of ptrs of stack blocks that
        !            60:  * have become covered by heap allocation.
        !            61:  * `tdystak' will return them to the heap.
        !            62:  */
        !            63: BLKPTR         stakbsy;
        !            64: 
        !            65: /* Base of the entire stack */
        !            66: STKPTR         stakbas;
        !            67: 
        !            68: /* Top of entire stack */
        !            69: STKPTR         brkend;
        !            70: 
        !            71: /* Base of current item */
        !            72: STKPTR         stakbot;
        !            73: 
        !            74: /* Top of current item */
        !            75: STKPTR         staktop;
        !            76: 
        !            77: /* Used with tdystak */
        !            78: STKPTR         savstak();

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