Nils O. Selåsdal
248 lines
8.3 KiB
C
248 lines
8.3 KiB
C
#ifndef UC_TAILQ_H_
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#define UC_TAILQ_H_
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#include "utils.h"
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/**
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* Doubly Linked List.
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* It is used either as
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* 1) a linked list "head" - a node serving to hold pointer to the
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* first and last node in a list
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* 2) a linked list entry - a node in the linked list
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*
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* This is variant of sys/queue.h TAILQ which avoids too many conditionals.
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* The struct TailQ serves both as an entry/node in a linked list,
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* and as head of a linked list.
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*
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* Note that unlike the sys/queue.h TAILQ, the list does
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* not begin/end with a NULL pointer. For a entry node, the beginning/end
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* is a back pointer to the head node.
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*
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* Traditional linked list TailQ
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* node->prev == NULL node->prev == head
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* node->next == NULL node->next == head
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*
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* Do not ever add an entry that's a NULL pointer.
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*
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*/
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struct TailQ {
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//pointer to next element, or for a head node,
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//pointer to the first entry
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struct TailQ *next;
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//pointer to previous element, or for a head node,
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//pointer to the last node
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struct TailQ *prev;
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};
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#define UC_TAILQ_HEAD_INIT(name) {&(name), &(name)}
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#define UC_TAILQ_HEAD(name)\
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struct TailQ name = UC_TAILQ_HEAD_INIT(name)
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//given 'ptr' as a pointer to a struct 'member',
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//find the struct that ptr is the member of, where
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//'type' is the type of the containing struct
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//This is basically UC_CONTAINER_OF in ucore/utils.h, this is here
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//to make tailq.h a standalone header
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#define UC_TAILQ_CONTAINER(ptr, type, member) ({\
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typeof( ((type *)0)->member ) *__mptr = (ptr); \
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(type *)((void *)(unsigned char *)__mptr - offsetof(type, member) ); })
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static UC_INLINE void uc_tailq_init(struct TailQ *head)
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{
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head->prev = head;
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head->next = head;
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}
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/** Test if the tailq is empty
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*/
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static UC_INLINE int uc_tailq_empty(const struct TailQ *head)
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{
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return head->next == head;
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}
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/** Insert the entry between prev and next
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*/
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static UC_INLINE void uc_tailq_insert(struct TailQ *entry,
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struct TailQ *prev,
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struct TailQ *next)
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{
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entry->prev = prev;
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prev->next = entry;
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entry->next = next;
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next->prev = entry;
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}
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/** Insert entry to the tail(end) of the tailq
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*/
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static UC_INLINE void uc_tailq_insert_tail(struct TailQ *head, struct TailQ *entry)
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{
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//head becomes entry->next, signalling the end of the tailq
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uc_tailq_insert(entry, head->prev, head);
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}
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/** Insert entry to the head(start) of the tailq
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*/
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static UC_INLINE void uc_tailq_insert_head(struct TailQ *head, struct TailQ *entry)
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{
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//head becomes entry->prev, signalling the end of the tailq
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uc_tailq_insert(entry, head, head->next);
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}
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/** Link the first and second entry together,
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*/
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static UC_INLINE void uc_tailq_link(struct TailQ *first, struct TailQ *second)
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{
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first->next = second;
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second->prev = first;
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}
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/** Remove the entry from the tailq it is part of.
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* (It *must* already be part of a tailq.
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*/
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static UC_INLINE void uc_tailq_remove(struct TailQ *entry)
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{
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uc_tailq_link(entry->prev, entry->next);
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//help catch illegal use:
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entry->next = (void*)0x101;
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entry->prev = (void*)0x102;
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}
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/** Move entry from its current tailq to the head of another tailq.
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* (entry must be part of a tailq)
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*/
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static UC_INLINE void uc_tailq_move_head(struct TailQ *entry, struct TailQ *head)
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{
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uc_tailq_link(entry->prev, entry->next);
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uc_tailq_insert(entry, head, head->next);
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}
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/** Move entry from its current tailq to the tail of another tailq.
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* (entry must be part of a tailq)
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*/
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static UC_INLINE void uc_tailq_move_tail(struct TailQ *entry, struct TailQ *head)
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{
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uc_tailq_link(entry->prev, entry->next);
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uc_tailq_insert(entry, head->prev, head);
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}
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//FIRST/NEXT/LAST/PREV macros similar to sys/queue.h
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//Note that unlike the standard TAILQ, you have to check
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// != head instead of != NULL to determine if the tailq entry
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// exists
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#define UC_TAILQ_FIRST(head)\
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((head)->next)
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#define UC_TAILQ_NEXT(entry)\
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((entry)->next)
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#define UC_TAILQ_LAST(head)\
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((head)->prev)
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#define UC_TAILQ_PREV(entry)\
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((entry)->prev)
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/** Iterate over a tailq. The tailq cannot be altered while iterating.
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*
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* @param entry a struct TailQ* to which each element is assigned.
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* @param head the struct TailQ* head of the tailq
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*/
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#define UC_TAILQ_FOREACH(entry, head)\
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for ((entry) = UC_TAILQ_FIRST(head); \
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(entry) != (head); \
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(entry) = UC_TAILQ_NEXT(entry))
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/** Iterate over the containing element in a tailq.
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* The tailq cannot be altered while iterating.
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*
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* @param ptr a pointer to the struct which the tailq nodes are member of
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* @param member the member of ptr that is the tailq node
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* @param head the struct TailQ* head of the tailq
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*/
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#define UC_TAILQ_FOREACH_CONTAINER(ptr, member, head)\
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for ((ptr) = UC_TAILQ_CONTAINER(UC_TAILQ_FIRST(head), typeof(*ptr), member);\
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&(ptr)->member != (head);\
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(ptr) = UC_TAILQ_CONTAINER(UC_TAILQ_NEXT(&(ptr)->member), typeof(*ptr), member))
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/** Iterate over a tailq in reverse order.
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* The tailq cannot be altered while iterating.
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*
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* @param entry a struct TailQ* to which each element is assigned.
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* @param head the struct TailQ* head of the tailq
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*/
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#define UC_TAILQ_FOREACH_REVERSE(entry, head)\
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for ((entry) = UC_TAILQ_LAST(entry); \
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(entry) != (head); \
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(entry) = UC_TAILQ_PREV(entry)
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/** Iterate over the containing element in a tailq in reverse.
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* The tailq cannot be altered while iterating.
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*
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* @param ptr a pointer to the struct which the tailq nodes are member of
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* @param member the member of ptr that is the tailq node
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* @param head the struct TailQ* head of the tailq
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*/
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#define UC_TAILQ_FOREACH_REVERSE_CONTAINER(ptr, member, head)\
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for ((ptr) = UC_TAILQ_CONTAINER(UC_TAILQ_LAST(head), typeof(*ptr), member);\
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&(ptr)->member != (head);\
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(ptr) = UC_TAILQ_CONTAINER(UC_TAILQ_PREV(&(ptr)->member), typeof(*ptr), member))
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/** Iterate over a tailq. safe to remove the entry when iterating.
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*
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* @param entry a struct TailQ* to which each element is assigned.
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* @param nxt a struct TailQ* needed for temporary storage.
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* @param head the struct TailQ* head of the tailq
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*/
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#define UC_TAILQ_FOREACH_SAFE(entry, nxt, head)\
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for ((entry) = UC_TAILQ_FIRST(head), (nxt) = UC_TAILQ_NEXT(entry); \
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(entry) != (head); \
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(entry) = (nxt), (nxt) = UC_TAILQ_NEXT(entry))\
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/** Iterate over the containing element in a tailq, safe to remove
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* the entry when iterating
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*
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* @param ptr a pointer to the struct which the tailq nodes are member of
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* @param nxt same type as ptr needed for temporary storage.
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* @param member the member of ptr that is the tailq node
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* @param head the struct TailQ* head of the tailq
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*/
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#define UC_TAILQ_FOREACH_CONTAINER_SAFE(ptr, nxt, member, head)\
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for ((ptr) = UC_TAILQ_CONTAINER(UC_TAILQ_FIRST(head), typeof(*ptr), member),\
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(nxt) = UC_TAILQ_CONTAINER(UC_TAILQ_NEXT(&(ptr)->member), typeof(*ptr), member);\
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&(ptr)->member != (head);\
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(ptr) = (nxt),\
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(nxt) = UC_TAILQ_CONTAINER(UC_TAILQ_NEXT(&(ptr)->member), typeof(*ptr), member))
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/** Iterate over a tailq in reverse order. safe to remove the entry when
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* iterating.
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*
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* @param entry a struct TailQ* to which each element is assigned.
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* @param prv a struct TailQ* needed for temporary storage.
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* @param head the struct TailQ* head of the tailq
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*/
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#define UC_TAILQ_FOREACH_REVERSE_SAFE(entry, prv, head)\
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for ((entry) = UC_TAILQ_LAST(head), (prv) = UC_TAILQ_PREV(entry); \
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(entry) != (head); \
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(entry) = (prv), (prv) = UC_TAILQ_PREV(entry))\
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/** Iterate over the containing element in a tailq in reverse order, safe
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* to remove the entry when iterating
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*
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* @param ptr a pointer to the struct which the tailq nodes are member of
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* @param prv same type as ptr needed for temporary storage.
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* @param member the member of ptr that is the tailq node
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* @param head the struct TailQ* head of the tailq
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*/
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#define UC_TAILQ_FOREACH_REVERSE_CONTAINER_SAFE(ptr, prv, member, head)\
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for ((ptr) = UC_TAILQ_CONTAINER(UC_TAILQ_LAST(head), typeof(*ptr), member),\
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(prv) = UC_TAILQ_CONTAINER(UC_TAILQ_PREV(&(ptr)->member), typeof(*ptr), member);\
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&(ptr)->member != (head);\
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(ptr) = (prv),\
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(prv) = UC_TAILQ_CONTAINER(UC_TAILQ_NEXT(&(ptr)->member), typeof(*ptr), member))
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#endif
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