diff --git a/include/rtti/typeinfo.h b/include/rtti/typeinfo.h
index 467d4d0..cb90a16 100644
--- a/include/rtti/typeinfo.h
+++ b/include/rtti/typeinfo.h
@@ -134,6 +134,19 @@ typedef struct {
     length_fn_t length;
 } intf_length_t;
 
+/* set */
+typedef int (*bit_test_fn_t)(meta_obj_t*, unsigned long);
+typedef int (*bit_set_fn_t)(meta_obj_t*, unsigned long);
+typedef int (*bit_clr_fn_t)(meta_obj_t*, unsigned long);
+typedef int (*bit_clrall_fn_t)(meta_obj_t*);
+
+typedef struct {
+    bit_test_fn_t   test;
+    bit_set_fn_t    set;
+    bit_clr_fn_t    clr;
+    bit_clrall_fn_t clrall;
+} intf_bitmap_t;
+
 typedef struct {
     intf_lock_t*      lock;
     intf_tostring_t*  toString;
@@ -141,6 +154,7 @@ typedef struct {
     intf_reference_t* reference;
     intf_hash_t*      hash;
     intf_length_t*    length;
+    intf_bitmap_t*    bitmap;
 } interface_table_t;
 
 struct typeinfo_ {
@@ -165,7 +179,7 @@ extern int     is_rtti_obj(var);
 extern int     lock(var, uint64_t);
 extern void    unlock(var);
 extern char*   toString(var, ...);
-extern int     iter_make(iterator_t*, var,...);
+extern int     iter_make(iterator_t*, var, ...);
 extern int     iter_next(iterator_t*, void**);
 extern int     iter_reset(iterator_t*);
 extern void    iter_destroy(iterator_t*);
diff --git a/src/bitmap.c b/src/bitmap.c
new file mode 100644
index 0000000..6e571f2
--- /dev/null
+++ b/src/bitmap.c
@@ -0,0 +1,77 @@
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "rtti.h"
+
+int bit_test(var v, unsigned long idx)
+{
+    meta_obj_t*   obj    = NULL;
+    bit_test_fn_t method = NULL;
+
+    obj = RTTI_DATA_TO_OBJ(v);
+    if (RTTI_OBJ_INVALID(obj)) {
+        return -EINVAL;
+    }
+
+    RTTI_GET_METHOD(method, obj, bitmap, test);
+    if (method == NULL) {
+        return -EINVAL;
+    }
+
+    return method(obj, idx);
+}
+
+int bit_set(var v, unsigned long idx)
+{
+    meta_obj_t*   obj    = NULL;
+    bit_test_fn_t method = NULL;
+
+    obj = RTTI_DATA_TO_OBJ(v);
+    if (RTTI_OBJ_INVALID(obj)) {
+        return -EINVAL;
+    }
+
+    RTTI_GET_METHOD(method, obj, bitmap, set);
+    if (method == NULL) {
+        return -EINVAL;
+    }
+
+    return method(obj, idx);
+}
+
+int bit_clr(var v, unsigned long idx)
+{
+    meta_obj_t*   obj    = NULL;
+    bit_test_fn_t method = NULL;
+
+    obj = RTTI_DATA_TO_OBJ(v);
+    if (RTTI_OBJ_INVALID(obj)) {
+        return -EINVAL;
+    }
+
+    RTTI_GET_METHOD(method, obj, bitmap, clr);
+    if (method == NULL) {
+        return -EINVAL;
+    }
+
+    return method(obj, idx);
+}
+
+int bit_clrall(var v)
+{
+    meta_obj_t*   obj    = NULL;
+    bit_test_fn_t method = NULL;
+
+    obj = RTTI_DATA_TO_OBJ(v);
+    if (RTTI_OBJ_INVALID(obj)) {
+        return -EINVAL;
+    }
+
+    RTTI_GET_METHOD(method, obj, bitmap, clrall);
+    if (method == NULL) {
+        return -EINVAL;
+    }
+
+    return method(obj);
+}
diff --git a/src/meson.build b/src/meson.build
index 5f083eb..276c77d 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -8,6 +8,7 @@ librtti_c_srcs=[
   'str.c',
   'hash.c',
   'length.c',
+  'bitmap.c',
 ]
 
 
diff --git a/src/str.c b/src/str.c
index 3d85bc6..d48ad51 100644
--- a/src/str.c
+++ b/src/str.c
@@ -23,7 +23,7 @@ char* toString(var v, ...)
     }
 
     va_start(ap, v);
-    s = method(v, ap);
+    s = method(obj, ap);
     va_end(ap);
 
     return s;