70 lines
2.6 KiB
TeX
70 lines
2.6 KiB
TeX
\begin{itemize}
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\item \textbf{Name} : DpgenShift -- Shifter Macro-Generator
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\item \textbf{Synopsys} :
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\begin{verbatim}
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Generate ( 'DpgenShift', modelname
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, param = { 'nbit' : n
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, 'physical' : True
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}
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)
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\end{verbatim}
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\item \textbf{Description} : Generates a \verb-n- bits shifter named \verb-modelname-.
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\item \textbf{Terminal Names} :
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\begin{itemize}
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\item \textbf{op} : select the kind of shift (input, 2 bits)
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\item \textbf{shamt} : the shift amount (input, \verb-Y- bits)
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\item \textbf{i} : value to shift (input, \verb-n- bits)
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\item \textbf{o} : output (\verb-n- bits)
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\item \textbf{vdd} : power
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\item \textbf{vss} : ground
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\end{itemize}
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\item \textbf{Parameters} : Parameters are given in the map \verb-param-.
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\begin{itemize}
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\item \textbf{nbit} (mandatory) : Defines the size of the generator
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\item \textbf{physical} (optional, default value : False) : In order to generate a layout
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\end{itemize}
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\item \textbf{How it works} :
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\begin{itemize}
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\item If the \verb-op[0]- signal is set to \verb-one-, performs a right shift, performs a left shift otherwise.
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\item If the \verb-op[1]- signal is set to \verb-one-, performs an arithmetic shift (only meaningful in case of a right shift).
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\item shamt : specifies the shift amount. The width of this signal (\verb-Y-) is computed from the operator's width : \verb-Y = ceil(log2(n)) -- 1
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\end{itemize}
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% \item \textbf{Behavior} :
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%\begin{verbatim}
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%\end{verbatim}
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\item \textbf{Example} :
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\begin{verbatim}
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from stratus import *
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class inst_shifter ( Model ) :
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def Interface ( self ) :
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self.instop = SignalIn ( "instop", 2 )
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self.instshamt = SignalIn ( "instshamt", 2 )
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self.insti = SignalIn ( "insti", 4 )
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self.insto = SignalOut ( "insto", 4 )
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self.vdd = VddIn ( "vdd" )
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self.vss = VssIn ( "vss" )
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def Netlist ( self ) :
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Generate ( 'DpgenShifter', 'shifter_4'
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, param = { 'nbit' : 4
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, 'physical' : True
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}
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)
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self.I = Inst ( 'shifter_4', 'inst'
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, map = { 'op' : self.instop
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, 'shamt' : self.instshamt
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, 'i' : self.insti
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, 'o' : self.insto
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, 'vdd' : self.vdd
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, 'vss' : self.vss
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}
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)
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def Layout ( self ) :
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Place ( self.I, NOSYM, Ref(0, 0) )
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\end{verbatim}
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\end{itemize}
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