2 files changed, 88 insertions, 1 deletions

diff --git a/util/arena.h b/util/arena.h
index 3d82b95..1142321 100644
--- a/util/arena.h
+++ b/util/arena.h
@@ -9,18 +9,26 @@ struct arena_ctx {
     size_t offset;
 };
 
+
 #define ARENA_CTX_INIT(buffer, sz) (struct arena_ctx){(buffer), (sz), 0}
 void *arena_allocate(struct arena_ctx *ctx, size_t sz);
 void arena_reset(struct arena_ctx *ctx);
 
 #ifdef ARENA_IMPLEMENTATION
+#define ARENA_ALLIGNMENT 2
 
+// #include <assert.h>
 void *arena_allocate(struct arena_ctx *ctx, size_t sz)
 {
+    if(sz % ARENA_ALLIGNMENT != 0)
+        sz += ARENA_ALLIGNMENT - (sz % ARENA_ALLIGNMENT);
+
     if(ctx->offset + sz > ctx->size) return NULL;
 
-    void *off = ctx->buffer + ctx->offset;
+    void *off = (void *)((intptr_t)ctx->buffer + ctx->offset);
     ctx->offset += sz;
+
+    // assert(((intptr_t)off & 0x1) == 0);
     return off;
 }
 
diff --git a/util/list.h b/util/list.h
new file mode 100644
index 0000000..d9531ea
--- /dev/null
+++ b/util/list.h
@@ -0,0 +1,79 @@
+#ifndef LIST_H
+#define LIST_H
+
+// #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
+#define container_of(ptr, type, member) ((type *)((char *)(ptr) - offsetof(type, member)))
+
+struct list_head {
+    struct list_head *prev;
+    struct list_head *next;
+};
+
+#define LIST_END NULL
+
+#define LIST_EMPTY(list) do {    \
+        (list)->next = LIST_END; \
+        (list)->prev = LIST_END; \
+    } while(0);
+
+#define list_entry(ptr, type, member) \
+	container_of(ptr, type, member)
+
+#define list_next_entry(entry, type, member) \
+    list_entry(entry->member.next, type, member)
+
+#define list_for_each(pos, start)                               \
+	for(struct list_head *pos = start; pos; pos = pos->next)
+#define list_for_each_entry(type, entry, member, start)         \
+	for(type *entry = list_entry((start), type, member);        \
+        entry;                                                  \
+        entry = (entry->member.next == LIST_END ? NULL :        \
+                 list_next_entry(entry, type, member)))
+
+#define list_for_each_safe(pos, start)                          \
+	for(struct list_head *pos = (start), *__next = LIST_END;    \
+        pos && (__next = pos->next,1);                          \
+        pos = __next)
+
+static inline int list_is_head(struct list_head *l)
+{
+    return l->prev == LIST_END;
+}
+
+static inline int list_is_tail(struct list_head *l)
+{
+    return l->next == LIST_END;
+}
+
+static inline struct list_head *list_get_head(struct list_head *l)
+{
+    while(!list_is_head(l)) l = l->prev;
+    return l;
+}
+
+static inline struct list_head *list_get_tail(struct list_head *l)
+{
+    while(!list_is_tail(l)) l = l->next;
+    return l;
+}
+
+static inline struct list_head *list_add(
+    struct list_head *head,
+    struct list_head *new)
+{
+    if(head) {
+        // new->next = head->next;
+        head->next = new;
+    }
+    new->prev = head;
+    return new;
+}
+
+static inline size_t list_len(struct list_head *head)
+{
+    size_t n = 0;
+    list_for_each(pos, list_get_head(head)) n++;
+    return n;
+}
+
+#endif