diff --git a/.sconsign.dblite b/.sconsign.dblite
deleted file mode 100644
index 545bc48..0000000
Binary files a/.sconsign.dblite and /dev/null differ
diff --git a/src/uchardet.cpp b/src/uchardet.cpp
index 4edda4e..57378ea 100644
--- a/src/uchardet.cpp
+++ b/src/uchardet.cpp
@@ -81,11 +81,10 @@ void uchardet_delete(uchardet_t ud)
     delete reinterpret_cast<DllDetector*>(ud);
 }
 
-void uchardet_handle_data(uchardet_t ud, const char * data, size_t len)
+int uchardet_handle_data(uchardet_t ud, const char * data, size_t len)
 {
     nsresult ret = reinterpret_cast<DllDetector*>(ud)->HandleData(data, (PRUint32)len);
-    if (ret != NS_OK)
-        ; //TODO
+    return (ret != NS_OK);
 }
 
 void uchardet_data_end(uchardet_t ud)
diff --git a/src/uchardet.h b/src/uchardet.h
index 7d2a466..4e76636 100644
--- a/src/uchardet.h
+++ b/src/uchardet.h
@@ -77,35 +77,46 @@ extern "C" {
 
 typedef void * uchardet_t;
 
+/**
+ * Create an encoding detector.
+ * @return a handle of a instance of uchardet
+ */
 uchardet_t uchardet_new();
 
+/**
+ * Delete an encoding detector.
+ * @param ud [in] handle of a instance of uchardet
+ */
 void uchardet_delete(uchardet_t ud);
 
-
 /**
  * Feed data to an encoding detector.
+ * @param ud [in] handle of a instance of uchardet
  * @param data [in] data
+ * @param len [in] number of byte of data
+ * @return non-zero number on failure.
  */
-void uchardet_handle_data(uchardet_t ud, const char * data, size_t len);
+int uchardet_handle_data(uchardet_t ud, const char * data, size_t len);
 
 /**
  * Notify an end of data to an encoding detctor.
+ * @param ud [in] handle of a instance of uchardet
  */
 void uchardet_data_end(uchardet_t ud);
 
 /**
  * Reset an encoding detector.
+ * @param ud [in] handle of a instance of uchardet
  */
 void uchardet_reset(uchardet_t ud);
 
 /**
  * Get the name of encoding that was detected.
+ * @param ud [in] handle of a instance of uchardet
  * @return name of charset
  */
 const char * uchardet_get_charset(uchardet_t ud);
 
-
-
 #ifdef __cplusplus
 }
 #endif