\begin{itemize}
    \item \textbf{Name} : DpgenAdsb2f -- Adder/Substractor Macro-Generator
    \item \textbf{Synopsys} :
\begin{verbatim}
Generate ( 'DpgenAdsb2f', modelname
         , param = { 'nbit'       : n
                   , 'physical'   : True
                   , 'behavioral' : True
                   }
         )
\end{verbatim}
    \item \textbf{Description} : Generates a \verb-n- bits adder/substractor named \verb-modelname-.
    \item \textbf{Terminal Names} :
    \begin{itemize}
        \item \textbf{i0} : First operand (input, \verb-n- bits)
        \item \textbf{i1} : Second operand (input, \verb-n- bits)
        \item \textbf{q} : Output operand (ouput, \verb-n- bits)
        \item \textbf{add\_sub} : Select addition or substraction (input, 1 bit)
        \item \textbf{c31} : Sarry out. In unsigned mode, this is the overflow (output, 1 bit)
        \item \textbf{c30} : Used to compute overflow in signed mode : \verb-overflow = c31 xor c30- (output, 1 bit)
        \item \textbf{vdd} : power
        \item \textbf{vss} : ground
    \end{itemize}
    \item \textbf{Parameters} : Parameters are given in the map \verb-param-.
    \begin{itemize}
        \item \textbf{nbit} (mandatory) : Defines the size of the generator
        \item \textbf{physical} (optional, default value : False) : In order to generate a layout
        \item \textbf{behavioral} (optional, default value : False) : In order to generate a behavior
    \end{itemize}
    \item \textbf{How it works} :
    \begin{itemize}
        \item If the \verb-add_sub- signal is set to \verb-zero-, an addition is performed, otherwise it's a substraction.
        \item Operation can be either signed or unsigned. In unsigned mode \verb-c31- is the overflow ; in signed mode you have to compute overflow by \emph{XORing} \verb-c31- and \verb-c30-
    \end{itemize}    
%    \item \textbf{Behavior} :
%\begin{verbatim}
%\end{verbatim}
    \item \textbf{Example} :
\begin{verbatim}
from stratus import *

class inst_ADSB2F ( Model ) :

  def Interface ( self ) :
    self.in1 = SignalIn  ( "in1", 8 )
    self.in2 = SignalIn  ( "in2", 8 )
    self.out = SignalOut (   "o", 8 )
    self.as  = SignalIn  (  "as", 1 )
    self.c0  = SignalOut (  "c0", 1 )
    self.c1  = SignalOut (  "c1", 1 )
    
    self.vdd = VddIn ( "vdd" )
    self.vss = VssIn ( "vss" )
    
  def Netlist ( self ) :
    Generate ( 'DpgenAdsb2f', 'adder_8'
             , param = { 'nbit'     : 8
                       , 'physical' : True
                       }
             )       
    self.I = Inst ( 'adder_8', 'inst'
                  , map = { 'i0'      : self.in1
                          , 'i1'      : self.in2
                          , 'add_sub' : self.as
                          , 'q'       : self.out
                          , 'c30'     : self.c0
                          , 'c31'     : self.c1
                          , 'vdd'     : self.vdd
                          , 'vss'     : self.vss
                          }
                  )
      
  def Layout ( self ) :
    Place ( self.I, NOSYM, Ref(0, 0) )
\end{verbatim}
\end{itemize}
