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Annotation of researchv8dc/cmd/sh/stak.h, revision 1.1.1.1

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                setstak(x)      (staktop=absstak(x))
                     19: #define                pushstak(c)     (*staktop++=(c))
                     20: #define                zerostak()      (*staktop=0)
                     21: 
                     22: /* Used to address an item left on the top of
                     23:  * the stack (very temporary)
                     24:  */
                     25: #define                curstak()       (staktop)
                     26: 
                     27: /* `usestak' before `pushstak' then `fixstak'
                     28:  * These routines are safe against heap
                     29:  * being allocated.
                     30:  */
                     31: #define                usestak()       {locstak();}
                     32: 
                     33: /* for local use only since it hands
                     34:  * out a real address for the stack top
                     35:  */
                     36: extern char            *locstak();
                     37: 
                     38: /* Will allocate the item being used and return its
                     39:  * address (safe now).
                     40:  */
                     41: #define                fixstak()       endstak(staktop)
                     42: 
                     43: /* For use after `locstak' to hand back
                     44:  * new stack top and then allocate item
                     45:  */
                     46: extern char            *endstak();
                     47: 
                     48: /* Copy a string onto the stack and
                     49:  * allocate the space.
                     50:  */
                     51: extern char            *cpystak();
                     52: 
                     53: /* Allocate given ammount of stack space */
                     54: extern char            *getstak();
                     55: 
                     56: /* A chain of ptrs of stack blocks that
                     57:  * have become covered by heap allocation.
                     58:  * `tdystak' will return them to the heap.
                     59:  */
                     60: extern struct blk      *stakbsy;
                     61: 
                     62: /* Base of the entire stack */
                     63: extern char            *stakbas;
                     64: 
                     65: /* Top of entire stack */
                     66: extern char            *brkend;
                     67: 
                     68: /* Base of current item */
                     69: extern char            *stakbot;
                     70: 
                     71: /* Top of current item */
                     72: extern char            *staktop;
                     73: 
                     74: /* Used with tdystak */
                     75: extern char            *savstak();

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