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Annotation of embedaddon/bird/lib/lists.h, revision 1.1.1.1

1.1       misho       1: /*
                      2:  *     BIRD Library -- Linked Lists
                      3:  *
                      4:  *     (c) 1998 Martin Mares <mj@ucw.cz>
                      5:  *
                      6:  *     Can be freely distributed and used under the terms of the GNU GPL.
                      7:  */
                      8: 
                      9: #ifndef _BIRD_LISTS_H_
                     10: #define _BIRD_LISTS_H_
                     11: 
                     12: /*
                     13:  * I admit the list structure is very tricky and also somewhat awkward,
                     14:  * but it's both efficient and easy to manipulate once one understands the
                     15:  * basic trick: The list head always contains two synthetic nodes which are
                     16:  * always present in the list: the head and the tail. But as the `next'
                     17:  * entry of the tail and the `prev' entry of the head are both NULL, the
                     18:  * nodes can overlap each other:
                     19:  *
                     20:  *     head    head_node.next
                     21:  *     null    head_node.prev  tail_node.next
                     22:  *     tail                    tail_node.prev
                     23:  */
                     24: 
                     25: typedef struct node {
                     26:   struct node *next, *prev;
                     27: } node;
                     28: 
                     29: typedef union list {                   /* In fact two overlayed nodes */
                     30:   struct {                             /* Head node */
                     31:     struct node head_node;
                     32:     void *head_padding;
                     33:   };
                     34:   struct {                             /* Tail node */
                     35:     void *tail_padding;
                     36:     struct node tail_node;
                     37:   };
                     38:   struct {                             /* Split to separate pointers */
                     39:     struct node *head;
                     40:     struct node *null;
                     41:     struct node *tail;
                     42:   };
                     43: } list;
                     44: 
                     45: 
                     46: #define NODE (node *)
                     47: #define HEAD(list) ((void *)((list).head))
                     48: #define TAIL(list) ((void *)((list).tail))
                     49: #define NODE_NEXT(n) ((void *)((NODE (n))->next))
                     50: #define NODE_VALID(n) ((NODE (n))->next)
                     51: #define WALK_LIST(n,list) for(n=HEAD(list); NODE_VALID(n); n=NODE_NEXT(n))
                     52: #define WALK_LIST2(n,nn,list,pos) \
                     53:   for(nn=(list).head; NODE_VALID(nn) && (n=SKIP_BACK(typeof(*n),pos,nn)); nn=nn->next)
                     54: #define WALK_LIST_DELSAFE(n,nxt,list) \
                     55:      for(n=HEAD(list); nxt=NODE_NEXT(n); n=(void *) nxt)
                     56: /* WALK_LIST_FIRST supposes that called code removes each processed node */
                     57: #define WALK_LIST_FIRST(n,list) \
                     58:      while(n=HEAD(list), (NODE (n))->next)
                     59: #define WALK_LIST_BACKWARDS(n,list) for(n=TAIL(list);(NODE (n))->prev; \
                     60:                                n=(void *)((NODE (n))->prev))
                     61: #define WALK_LIST_BACKWARDS_DELSAFE(n,prv,list) \
                     62:      for(n=TAIL(list); prv=(void *)((NODE (n))->prev); n=(void *) prv)
                     63: 
                     64: #define EMPTY_LIST(list) (!(list).head->next)
                     65: 
                     66: 
                     67: #ifndef _BIRD_LISTS_C_
                     68: #define LIST_INLINE static inline
                     69: #include "lib/lists.c"
                     70: #undef LIST_INLINE
                     71: 
                     72: #else /* _BIRD_LISTS_C_ */
                     73: #define LIST_INLINE
                     74: void add_tail(list *, node *);
                     75: void add_head(list *, node *);
                     76: void rem_node(node *);
                     77: void add_tail_list(list *, list *);
                     78: void init_list(list *);
                     79: void insert_node(node *, node *);
                     80: #endif
                     81: 
                     82: #endif