Implement trivial linked list

    *  Bring-your-own-node (generic / zero allocations)
    *  Doubly-linked and circular, forward and backward traversable
    *  Random insert/removal in constant time
    *  All operations are no-fail
    * [Some type safety concessions though]

Signed-off-by: Malfurious <m@lfurio.us>

3 files changed, 43 insertions, 0 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7a13a74..b8644a7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,6 +16,7 @@ add_compile_definitions(
 add_executable(${PROJECT_NAME}
     console.c
     helpers.c
+    list.c
     misplays.c
 )
 
diff --git a/list.c b/list.c
new file mode 100644
index 0000000..9cf1ad0
--- /dev/null
+++ b/list.c
@@ -0,0 +1,32 @@
+#include <stddef.h>
+#include "list.h"
+
+struct _list {
+    LINKEDLIST;
+};
+
+void list_init(struct list *list) {
+    list->tail = list;
+    list->head = list;
+    list->end = list;
+}
+
+void list_insert(void *_next, void *_node) {
+    struct _list *node = _node;
+    struct _list *next = _next;
+    struct _list *prev = next->prev;
+    next->prev = node;
+    prev->next = node;
+    node->next = next;
+    node->prev = prev;
+}
+
+void list_remove(void *_node) {
+    struct _list *node = _node;
+    struct _list *next = node->next;
+    struct _list *prev = node->prev;
+    next->prev = prev;
+    prev->next = next;
+    node->next = NULL;
+    node->prev = NULL;
+}
diff --git a/list.h b/list.h
new file mode 100644
index 0000000..7d7a272
--- /dev/null
+++ b/list.h
@@ -0,0 +1,10 @@
+#pragma once
+#define LINKEDLIST void *prev, *next
+
+struct list {
+    void *tail, *head, *end;
+};
+
+extern void list_init(struct list *list);
+extern void list_insert(void *_next, void *_node);
+extern void list_remove(void *_node);