Add new functions to the list_head system.

libc/inc/sys/list_head.h

@@ -22,31 +22,37 @@ typedef struct list_head {
 #define list_entry(ptr, type, member) container_of(ptr, type, member)
 
 /// @brief Iterates over a list.
-/// @param pos    The &list_head to use as a loop cursor.
-/// @param head   The head for your list.
+/// @param pos the name of the iterator used to visit the list.
+/// @param head the head for your list.
 #define list_for_each(pos, head) \
     for ((pos) = (head)->next; (pos) != (head); (pos) = (pos)->next)
 
-/// @brief Iterates over a list backwards.
-/// @param pos    The &list_head to use as a loop cursor.
-/// @param head   The head for your list.
-#define list_for_each_prev(pos, head) \
-    for ((pos) = (head)->prev; (pos) != (head); (pos) = (pos)->prev)
-
 /// @brief Iterates over a list safe against removal of list entry.
-/// @param pos    The &list_head to use as a loop cursor.
-/// @param store  Another &list_head to use as temporary storage.
-/// @param head   The head for your list.
+/// @param pos the name of the iterator used to visit the list.
+/// @param store another list iterator to use as temporary storage.
+/// @param head the head for your list.
 #define list_for_each_safe(pos, store, head)                           \
     for ((pos) = (head)->next, (store) = (pos)->next; (pos) != (head); \
          (pos) = (store), (store) = (pos)->next)
 
-/// @brief Iterates over a list.
-/// @param pos    The &list_head to use as a loop cursor.
-/// @param head   The head for your list.
+/// @brief Iterates over a list, but declares the iterator.
+/// @param pos the name of the iterator used to visit the list.
+/// @param head the head for your list.
 #define list_for_each_decl(pos, head) \
     for (list_head * (pos) = (head)->next; (pos) != (head); (pos) = (pos)->next)
 
+/// @brief Iterates over a list backwards.
+/// @param pos the name of the iterator used to visit the list.
+/// @param head the head for your list.
+#define list_for_each_prev(pos, head) \
+    for ((pos) = (head)->prev; (pos) != (head); (pos) = (pos)->prev)
+
+/// @brief Iterates over a list backwards, but declares the iterator.
+/// @param pos the name of the iterator used to visit the list.
+/// @param head the head for your list.
+#define list_for_each_prev_decl(pos, head) \
+    for (list_head * (pos) = (head)->prev; (pos) != (head); (pos) = (pos)->prev)
+
 /// @brief Initializes the list_head.
 /// @param head The head of your list.
 static inline void list_head_init(list_head *head)
@@ -161,3 +167,31 @@ static inline void list_head_append(list_head *main, list_head *secondary)
         list_head_init(secondary);
     }
 }
+
+/// @brief Replaces entry1 with entry2, entry1 will be removed from the list.
+/// @param entry1 the first entry to remove.
+/// @param entry2 the second entry which will take the place of the first entry.
+static inline void list_head_replace(list_head *entry1, list_head *entry2)
+{
+    // First we need to remove the second entry.
+    list_head_remove(entry2);
+    // Then, we can place second entry where the first entry is.
+    entry2->next       = entry1->next;
+    entry2->next->prev = entry2;
+    entry2->prev       = entry1->prev;
+    entry2->prev->next = entry2;
+    // Re-initialize the first entry.
+    list_head_init(entry1);
+}
+
+/// @brief Swaps entry1 and entry2 inside the list.
+/// @param entry1 the first entry.
+/// @param entry2 the second entry.
+static inline void list_head_swap(list_head *entry1, list_head *entry2)
+{
+    list_head *pos = entry2->prev;
+    list_head_replace(entry1, entry2);
+    if (pos == entry1)
+        pos = entry2;
+    list_head_insert_after(entry1, pos);
+}

libc/inc/sys/list_head_algorithm.h

@@ -0,0 +1,48 @@
+/// @file list_head_algorithm.h
+/// @author Enrico Fraccaroli (enry.frak@gmail.com)
+/// @brief Some general algorithm that might come in handy while using list_head.
+/// @copyright (c) 2014-2023 This file is distributed under the MIT License.
+/// See LICENSE.md for details.
+
+#pragma once
+
+#include "list_head.h"
+
+/// @brief list_head comparison function.
+typedef int (*list_head_compare)(const list_head *, const list_head *);
+
+/// @brief -
+/// @param list
+/// @param compare
+void list_head_sort(list_head *list, list_head_compare compare)
+{
+    list_head *current = NULL, *index = NULL, *next = NULL;
+    // Check whether list is empty
+    if (list_head_empty(list)) {
+        return;
+    }
+    // Keeps track if we need to restart the outer loop.
+    int restart = 0;
+    // Current will point to head
+    for (current = list->next; current->next != list;) {
+        // Save pointer to next.
+        next = current->next;
+        // Reset restart flag.
+        restart = 0;
+        // Index will point to node next to current
+        for (index = current->next; index != list; index = index->next) {
+            // If current's data is greater than index's data, swap the data of
+            // current and index
+            if (compare(current, index)) {
+                list_head_swap(index, current);
+                restart = 1;
+            }
+        }
+        // Check if we need to restart.
+        if (restart)
+            current = list->next;
+        else
+            current = next;
+    }
+}
+