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Annotation of researchv9/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                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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