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102 lines
3.0 KiB
C
102 lines
3.0 KiB
C
/*
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* BIRD Library -- Linked Lists
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*
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* (c) 1998 Martin Mares <mj@ucw.cz>
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*
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* Can be freely distributed and used under the terms of the GNU GPL.
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*/
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#ifndef _BIRD_LISTS_H_
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#define _BIRD_LISTS_H_
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/*
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* I admit the list structure is very tricky and also somewhat awkward,
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* but it's both efficient and easy to manipulate once one understands the
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* basic trick: The list head always contains two synthetic nodes which are
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* always present in the list: the head and the tail. But as the `next'
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* entry of the tail and the `prev' entry of the head are both NULL, the
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* nodes can overlap each other:
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*
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* head head_node.next
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* null head_node.prev tail_node.next
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* tail tail_node.prev
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*/
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typedef struct node {
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struct node *next, *prev;
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} node;
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typedef union list { /* In fact two overlayed nodes */
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struct { /* Head node */
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struct node head_node;
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void *head_padding;
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};
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struct { /* Tail node */
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void *tail_padding;
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struct node tail_node;
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};
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struct { /* Split to separate pointers */
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struct node *head;
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struct node *null;
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struct node *tail;
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};
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} list;
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#define STATIC_LIST_INIT(name) name = { .head = &name.tail_node, .tail = &name.head_node, .null = NULL }
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#define NODE (node *)
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#define HEAD(list) ((void *)((list).head))
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#define TAIL(list) ((void *)((list).tail))
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#define NODE_NEXT(n) ((void *)((NODE (n))->next))
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#define NODE_VALID(n) ((NODE (n))->next)
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#define WALK_LIST(n,list) for(n=HEAD(list); NODE_VALID(n); n=NODE_NEXT(n))
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#define WALK_LIST2(n,nn,list,pos) \
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for(nn=(list).head; NODE_VALID(nn) && (n=SKIP_BACK(typeof(*n),pos,nn)); nn=nn->next)
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#define WALK_LIST_DELSAFE(n,nxt,list) \
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for(n=HEAD(list); nxt=NODE_NEXT(n); n=(void *) nxt)
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#define WALK_LIST2_DELSAFE(n,nn,nxt,list,pos) \
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for(nn=HEAD(list); (nxt=nn->next) && (n=SKIP_BACK(typeof(*n),pos,nn)); nn=nxt)
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/* WALK_LIST_FIRST supposes that called code removes each processed node */
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#define WALK_LIST_FIRST(n,list) \
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while(n=HEAD(list), (NODE (n))->next)
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#define WALK_LIST_FIRST2(n,pos,list) \
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while(n=SKIP_BACK(typeof(*n),pos,HEAD(list)), (n)->pos.next)
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#define WALK_LIST_BACKWARDS(n,list) for(n=TAIL(list);(NODE (n))->prev; \
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n=(void *)((NODE (n))->prev))
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#define WALK_LIST_BACKWARDS_DELSAFE(n,prv,list) \
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for(n=TAIL(list); prv=(void *)((NODE (n))->prev); n=(void *) prv)
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#define EMPTY_LIST(list) (!(list).head->next)
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static inline bool
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enlisted(node *n)
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{
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switch ((!!n->next) + (!!n->prev))
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{
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case 0: return 0;
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case 2: return 1;
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case 1: bug("Garbled event list node");
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}
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bug("Maths is broken. And you should see a new heaven and a new earth: for the first heaven and the first earth had been passed away.");
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}
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#ifndef _BIRD_LISTS_C_
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#define LIST_INLINE static inline
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#include "lib/lists.c"
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#undef LIST_INLINE
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#else /* _BIRD_LISTS_C_ */
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#define LIST_INLINE
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void add_tail(list *, node *);
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void add_head(list *, node *);
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void rem_node(node *);
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void add_tail_list(list *, list *);
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void init_list(list *);
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void insert_node(node *, node *);
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uint list_length(list *);
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#endif
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#endif
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