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+#ifndef MRU_H
+#define MRU_H
+
+/**
+ * A simple most-recently-used cache, backed by a doubly-linked list.
+ *
+ * Usage is roughly:
+ *
+ * // Create a list. Zero-initialization is required.
+ * static struct mru cache;
+ * mru_append(&cache, item);
+ * ...
+ *
+ * // Iterate in MRU order.
+ * struct mru_entry *p;
+ * for (p = cache.head; p; p = p->next) {
+ * if (matches(p->item))
+ * break;
+ * }
+ *
+ * // Mark an item as used, moving it to the front of the list.
+ * mru_mark(&cache, p);
+ *
+ * // Reset the list to empty, cleaning up all resources.
+ * mru_clear(&cache);
+ *
+ * Note that you SHOULD NOT call mru_mark() and then continue traversing the
+ * list; it reorders the marked item to the front of the list, and therefore
+ * you will begin traversing the whole list again.
+ */
+
+struct mru_entry {
+ void *item;
+ struct mru_entry *prev, *next;
+};
+
+struct mru {
+ struct mru_entry *head, *tail;
+};
+
+void mru_append(struct mru *mru, void *item);
+void mru_mark(struct mru *mru, struct mru_entry *entry);
+void mru_clear(struct mru *mru);
+
+#endif /* MRU_H */