first commit, initial layout and some ideas I want to implement, included my linked list impl

include/nickel/linkedlist.h

@@ -0,0 +1,62 @@
+#include <stdlib.h>
+#include <stdbool.h>
+
+#ifndef __NICKEL_LINKEDLIST_H_
+#define __NICKEL_LINKEDLIST_H_
+
+typedef struct ni_list_node {
+  struct ni_list_node* next;
+  struct ni_list_node* prev;
+} ni_list_node;
+
+// sentinel type structure for head + count
+typedef struct ni_list {
+  ni_list_node head;
+  size_t count;
+} ni_list;
+
+// convenience ptr wrapper struct for a 'generic' list of pointers to things
+typedef struct ni_list_ptr {
+    ni_list_node link;
+    void* ptr;
+} ni_list_ptr;
+
+// List functions
+void ni_list__init(ni_list* l);
+bool ni_list__is_empty(ni_list* l);
+
+void ni_list__insert_after(ni_list* l, ni_list_node* entry, ni_list_node* n);
+void ni_list__insert_before(ni_list* l, ni_list_node* entry, ni_list_node* n);
+
+void ni_list__push_front(ni_list* l, ni_list_node* n);
+void ni_list__push_back(ni_list* l, ni_list_node* n);
+
+void ni_list__remove(ni_list* l, ni_list_node* n);
+
+static inline ni_list_node* ni_list__get_front(ni_list* l) {
+    // if l is_empty() front == NULL else return the first actual data baring node
+    return ni_list__is_empty(l) ? NULL : l->head.next;
+}
+
+static inline ni_list_node* ni_list__get_back(ni_list* l) {
+    // if l is_empty() front == NULL else return the last node in the list
+    return ni_list__is_empty(l) ? NULL : l->head.prev;
+}
+
+/* Iter Helpers */
+
+#define NI_LIST__FOREACH(lptr) \
+    for (ni_list_node* it = ni_list__get_front(lptr); it != &(lptr)->head; it = it->next)
+
+#define NI_LIST_FOREACH_SAFE(tmp, lptr) \
+    for (ni_list_node* it = ni_list__get_front(lptr), *tmp = it->next; \
+        it != &(lptr)->head; \
+        it = tmp, tmp = it-> next)
+
+// create a pointer to struct that contains a ni_list_node member
+// since we know the structure size at compile time we can do some math
+// to retreive the base address of the structure that contains our list node.
+#define NI_LIST_CONTAINER_OF(ptr, type, member) \
+    ((type*)((uint8_t*)(ptr) - offsetof(type, member)))
+
+#endif	/* __NICKEL_LINKEDLIST_H_ */