From d98f46ce647846b0aa30b2e16a30fd4e152a1bf5 Mon Sep 17 00:00:00 2001
From: Carlos Maiolino <cem@kernel.org>
Date: Thu, 10 Jul 2025 22:55:07 +0200
Subject: Add new code

Signed-off-by: Carlos Maiolino <cem@toxiclabs.cc>
---
 Algorithms/lists.h | 113 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 Algorithms/lists.h

(limited to 'Algorithms/lists.h')

diff --git a/Algorithms/lists.h b/Algorithms/lists.h
new file mode 100644
index 0000000..20ddb45
--- /dev/null
+++ b/Algorithms/lists.h
@@ -0,0 +1,113 @@
+#ifndef LIST_H
+#define LIST_H
+
+#include <stdlib.h>
+
+struct ListElmt {
+	void		*data;
+	struct ListElmt	*next;
+};
+
+struct List {
+	int	size;
+
+	int		(*match)(const void *key1, const void *key2);
+	void		(*destroy)(void *data);
+
+	struct ListElmt	*head, *tail;
+}
+
+/*
+ * Initializes a linked list
+ * List: Linked list to initialize
+ * destructor:	helper to destruct and free data allocated for the list
+ */
+void list_init(List *list, void (*destroy)(void *data));
+
+/*
+ * Destroy a linked list, its elements and calls its destructor.
+ * May or may not free memory, depends on its desctructor.
+ */
+void list_destroy(List *list);
+
+/*
+ * Insert a new element AFTER 'element'. If 'element is NULL, the new element is
+ * inserted at the head of the list. The new element contains a pointer to
+ * 'data', so, its pointer should remain valid as long as the element remains in
+ * the list. It's caller's responsibility to manage storage associated with data.
+ * Return: 0 if successful, negative otherwise
+ */
+int list_ins_next(List *list, ListElmt *element, const void *data);
+
+/*
+ * Remove the element just after 'element', if NULL, remove the element at the
+ * list head. Upon return, 'data' points to the data stored in the removed
+ * element. It's caller's responsibility to manage storage associated with data.
+ * Return: 0 if successful, negative otherwise
+ */
+int list_rem_next(List *list, ListElmt *element, void **data);
+
+#define list_size(list) ((list)->size)
+#define list_head(list) ((list)->head)
+#define list_tail(list) ((list)->tail)
+
+/* Return: 1 if the element is at the head of the list, 0 otherwise */
+#define list_is_head(list, element) ((element) == ((list)->head) ? 1 : 0)
+
+/* Return: 1 if the element is at the tail of the list, 0 otherwise */
+#define list_is_tail(element) ((element)->next == NULL ? 1 : 0)
+
+/* Return: Data stored in the element */
+#define list_data(element) ((element)->data)
+
+/* Return: Element following the specified element */
+#define list_next(element) ((element)->next)
+
+#endif /* LIST_H */
+
+
+#ifndef DLIST_H
+#define DLIST_H
+/* Doubly Linked List implementation */
+
+/* doubly-linked list elements */
+struct DListElmt {
+	void			*data;
+	struct DListElmt	*prev;
+	struct DListElmt	*next;
+};
+
+/* doubly-linked list structure */
+
+struct DList {
+	int	size;
+	int			(*match)(const void *key1, const void *key2);
+	void			(*destroy)(void *data);
+
+	struct	DlistElmt	*head, *tail;
+};
+
+/* Public interface */
+
+void dlist_init(struct Dlist *List, void (*destroy)(void *data));
+void dlist_destroy(struct DList *list);
+
+int dlist_ins_next(struct DList *list, struct DListElmt *element,
+		   const void *data);
+int dlist_ins_prev(struct DList *list, struct DListElmt *element,
+		   const void *data);
+
+int dlist_remove(struct DList *list, struct DListElmt *element, void **data);
+
+#define dlist_size(list) ((list)->size)
+#define dlist_head(list) ((list)->head)
+#define dlist_tail(list) ((list)->tail)
+
+#define dlist_is_head(element) ((element)->prev == NULL ? 1 : 0)
+#define dlist_is_tail(element) ((element)->next == NULL ? 1 : 0)
+
+#define dlist_data(element) ((element)->data)
+#define dlist_next(element) ((element)->next)
+#define dlist_prev(element) ((element)->prev)
+
+#endif /* DLIST_H */
-- 
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