-static inline GBUF_TYPE *
-GBUF_PREFIX(grow)(BUF_T *b, uns len)
+/**
+ * Sets the size of the buffer @b to at last @len.
+ * It grows in exponential manner, to ensure the total cost
+ * of reallocs is linear with the final size.
+ *
+ * You can tweak the final size (when you do not need to grow
+ * any more) by
+ * <<fun__GENERIC_LINK_|GBUF_PREFIX|set_size|,`GBUF_PREFIX(set_size)()`>>.
+ **/
+static inline GBUF_TYPE *GBUF_PREFIX(grow)(BUF_T *b, uns len)