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-rw-r--r--src/basic/list.h26
1 files changed, 26 insertions, 0 deletions
diff --git a/src/basic/list.h b/src/basic/list.h
index 2939216adb..760abcdab3 100644
--- a/src/basic/list.h
+++ b/src/basic/list.h
@@ -123,6 +123,32 @@
} \
} while(false)
+/* Insert an item before another one (a = where, b = what) */
+#define LIST_INSERT_BEFORE(name,head,a,b) \
+ do { \
+ typeof(*(head)) **_head = &(head), *_a = (a), *_b = (b); \
+ assert(_b); \
+ if (!_a) { \
+ if (!*_head) { \
+ _b->name##_next = NULL; \
+ _b->name##_prev = NULL; \
+ *_head = _b; \
+ } else { \
+ typeof(*(head)) *_tail = (head); \
+ while (_tail->name##_next) \
+ _tail = _tail->name##_next; \
+ _b->name##_next = NULL; \
+ _b->name##_prev = _tail; \
+ _tail->name##_next = _b; \
+ } \
+ } else { \
+ if ((_b->name##_prev = _a->name##_prev)) \
+ _b->name##_prev->name##_next = _b; \
+ _b->name##_next = _a; \
+ _a->name##_prev = _b; \
+ } \
+ } while(false)
+
#define LIST_JUST_US(name,item) \
(!(item)->name##_prev && !(item)->name##_next) \