1 files changed, 31 insertions, 0 deletions
diff --git a/freelist.h b/freelist.h
new file mode 100644
index 0000000..69ef976
--- /dev/null
+++ b/freelist.h
@@ -0,0 +1,31 @@
+#ifndef FREELIST_H
+#define FREELIST_H
+
+#include "arena.h"
+
+#define FREELIST_NEW(fl, a)\
+    (__typeof__(*(fl)))freelist_new((void**)(fl), sizeof(**(fl)), _Alignof(__typeof__(**(fl))), a)
+
+#define FREELIST_FREE(fl, p)\
+    freelist_free((void **)(fl), (void *)(p))
+
+static inline void *freelist_new(void **fl, size_t sz, size_t align, Arena *a) {
+	if (*fl) {
+		void *p = *fl;
+		void *next = *(void**)p;
+		*fl = next;
+		return p;
+	} else {
+		/* must pad and align for ptr to next in freelist */
+		if (sz    < sizeof(void *))   sz    = sizeof(void *);
+		if (align < _Alignof(void *)) align = _Alignof(void *);
+		return arena_alloc(a, sz, align);
+	}
+}
+
+static inline void freelist_free(void **fl, void *p) {
+	*(void **)p = *fl;
+	*fl = p;
+}
+
+#endif