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a08c4d1f08
Introduce a function to swap elements in a doubly linked list. This will be helpful when keeping the list of output layers sorted by priority. v2: re-define in terms of list_inserts and list_removes
61 lines
1 KiB
C
61 lines
1 KiB
C
#include "list.h"
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void
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liftoff_list_init(struct liftoff_list *list)
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{
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list->prev = list;
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list->next = list;
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}
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void
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liftoff_list_insert(struct liftoff_list *list, struct liftoff_list *elm)
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{
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elm->prev = list;
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elm->next = list->next;
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list->next = elm;
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elm->next->prev = elm;
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}
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void
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liftoff_list_remove(struct liftoff_list *elm)
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{
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elm->prev->next = elm->next;
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elm->next->prev = elm->prev;
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elm->next = NULL;
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elm->prev = NULL;
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}
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void
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liftoff_list_swap(struct liftoff_list *this, struct liftoff_list *other)
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{
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struct liftoff_list tmp;
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liftoff_list_insert(other, &tmp);
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liftoff_list_remove(other);
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liftoff_list_insert(this, other);
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liftoff_list_remove(this);
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liftoff_list_insert(&tmp, this);
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liftoff_list_remove(&tmp);
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}
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size_t
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liftoff_list_length(const struct liftoff_list *list)
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{
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struct liftoff_list *e;
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size_t count;
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count = 0;
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e = list->next;
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while (e != list) {
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e = e->next;
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count++;
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}
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return count;
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}
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bool
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liftoff_list_empty(const struct liftoff_list *list)
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{
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return list->next == list;
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}
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