Usually ptr lists are accessed iteratively via the FOR/END macros
but in few case we may need to access a given element in a list,
like for example when accessing a given argument of a function.
Create an helper doing that instead of open coding it.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
ptrlist.c | 22 ++++++++++++++++++++++
ptrlist.h | 1 +
2 files changed, 23 insertions(+)
diff --git a/ptrlist.c b/ptrlist.c
index 3677a347c..0fb281274 100644
--- a/ptrlist.c
+++ b/ptrlist.c
@@ -114,6 +114,28 @@ void *last_ptr_list(struct ptr_list *head)
return PTR_ENTRY_NOTAG(list, list->nr-1);
}
+///
+// get the nth element of a ptrlist
+// @head: the head of the list
+// @return: the nth element of the list or ``NULL`` if the list is too short.
+void *ptr_list_nth_entry(struct ptr_list *list, unsigned int idx)
+{
+ struct ptr_list *head = list;
+
+ if (!head)
+ return NULL;
+
+ do {
+ unsigned int nr = list->nr;
+
+ if (idx < nr)
+ return list->list[idx];
+ else
+ idx -= nr;
+ } while ((list = list->next) != head);
+ return NULL;
+}
+
///
// linearize the entries of a list
//
diff --git a/ptrlist.h b/ptrlist.h
index 2f0234784..2411e745a 100644
--- a/ptrlist.h
+++ b/ptrlist.h
@@ -44,6 +44,7 @@ extern bool ptr_list_multiple(const struct ptr_list *head);
extern int linearize_ptr_list(struct ptr_list *, void **, int);
extern void *first_ptr_list(struct ptr_list *);
extern void *last_ptr_list(struct ptr_list *);
+extern void *ptr_list_nth_entry(struct ptr_list *, unsigned int idx);
extern void pack_ptr_list(struct ptr_list **);
/*
--
2.19.0
