rework malloc_usable_size to use malloc_impl.h

diff --git a/src/malloc/malloc_usable_size.c b/src/malloc/malloc_usable_size.c
index 6743ea7..7a8ed6c 100644 (file)
--- a/src/malloc/malloc_usable_size.c
+++ b/src/malloc/malloc_usable_size.c
@@ -1,16 +1,8 @@
 #include <malloc.h>
+#include "malloc_impl.h"
 
 void *(*const __realloc_dep)(void *, size_t) = realloc;
 
-struct chunk {
-       size_t psize, csize;
-       struct chunk *next, *prev;
-};
-
-#define OVERHEAD (2*sizeof(size_t))
-#define CHUNK_SIZE(c) ((c)->csize & -2)
-#define MEM_TO_CHUNK(p) (struct chunk *)((char *)(p) - OVERHEAD)
-
 size_t malloc_usable_size(void *p)
 {
        return p ? CHUNK_SIZE(MEM_TO_CHUNK(p)) - OVERHEAD : 0;