Full rewrite

README.md

@@ -1,13 +1,38 @@
 
+## `arena_t arena_new()`
+
+Allocate a new arena.
+The underlying memory is allocated with mmap.
+
 
-`arena_t* arena_new()`
+## `void arena_delete(arena_t *a)`
 
-Initializes and returns new arena
+Delete memory mapped for arena.
+Should only be used with arenas from arena\_new().
 
-`void arena_reset(arena_t *a)`
 
-Free memory allocated in arena
+## `arena_t arena_attach(void *ptr, size_t size)`
 
-`void* arena_alloc(arena_t *a, size_t len)`
+Attach an arena to an existing memory region.
+The arena will not expand the region if space is exceeded.
+
+
+## `void *arena_detatch(arena_t arena)`
+Detach an arena from an existing memory region.
+
+
+## `void arena_reset(arena_t *a)`
+Reset an arena.
+
+
+
+## `void *arena_alloc(arena_t *a, size_t len)`
+Allocate memory from an arena.
+Returns NULL and sets errno on failure.
+
+
+
+## `void *arena_calloc(arena_t *a, size_t nmemb, size_t size)`
+Allocate and zero memory from an arena.
+Returns NULL and sets errno on failure.
 
-Allocate new memory using arena