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Annotation of 40BSD/cmd/sh/stak.h, revision 1.1.1.1

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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