[AUCTeX] How to tell LaTeX-fill-buffer not to reindent the verbatim regions.

[Hoang Trong Minh Tuan]

How to tell LaTeX-fill-buffer not to reindent some predefined regions .  
  I have defined <code> as a verbatim environment so that anything between  
\begin{code}   
 line1    
 line2   
 line3 
 line4 
\end{code}   
     will be treated as verbatim text.   The problem is that whenever I use LaTeX-fill-buffer command, it automatically re-indent everything inside, and change the structure that I want to keep in the verbatim region, e.g. 
\begin{code}  
  line1 line2  
  line3 line4 
\end{code}  
  Can someone give me a solution to avoid this problem? Thanks.

Tuan