\begin{itemize}
    \item Name : DpgenNul -- Zero Detector Macro-Generator
    \item Description : Generates a \verb-n- bits zero detector named \verb-modelname-.
    \item Terminal Names :
    \begin{itemize}
        \item i0 : value to check (input, \verb-n- bits)
        \item q : null flag (1 bit)
        \item vdd : power
        \item vss : ground
    \end{itemize}
    \item Parameters : Parameters are given with a map called \verb-param-.
    \begin{itemize}
        \item nbit : Defines the size of the generator
    \end{itemize}
    \item Behavior :
\begin{verbatim}
q <= '1' WHEN ( i0 = X"00000000" ) ELSE '0';
\end{verbatim}
    \item Example :
\begin{verbatim}
class myClass ( Model ) :
  def Interface ( self ) :
    self._in    = LogicIn  (  "in", 32 )
    
    self._out   = LogicOut ( "out", 1 )
    
    self._vdd   = VddIn    ( "vdd" )
    self._vss   = VssIn    ( "vss" )
    
  def Netlist ( self ) :
      
    Inst ( 'DpgenNul'
         , param = { 'nbit' : 32 }
         , map  = { 'i0'      : self._in
                  , 'nul'     : self._out
                  , 'vdd'     : self._vdd
                  , 'vss'     : self._vss
                  }
         )    
\end{verbatim}
\end{itemize}