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<H1><A NAME="SECTION000250000000000000000">
DpgenShift</A>
</H1>
<UL>
<LI><SPAN CLASS="textbf">Name</SPAN> : DpgenShift - Shifter Macro-Generator
</LI>
<LI><SPAN CLASS="textbf">Synopsys</SPAN> :
<PRE>
Generate ( 'DpgenShift', modelname
, param = { 'nbit' : n
, 'physical' : True
}
)
</PRE>
</LI>
<LI><SPAN CLASS="textbf">Description</SPAN> : Generates a <code>n</code> bits shifter named <code>modelname</code>.
</LI>
<LI><SPAN CLASS="textbf">Terminal Names</SPAN> :
<UL>
<LI><SPAN CLASS="textbf">op</SPAN> : select the kind of shift (input, 2 bits)
</LI>
<LI><SPAN CLASS="textbf">shamt</SPAN> : the shift amount (input, <code>Y</code> bits)
</LI>
<LI><SPAN CLASS="textbf">i</SPAN> : value to shift (input, <code>n</code> bits)
</LI>
<LI><SPAN CLASS="textbf">o</SPAN> : output (<code>n</code> bits)
</LI>
<LI><SPAN CLASS="textbf">vdd</SPAN> : power
</LI>
<LI><SPAN CLASS="textbf">vss</SPAN> : ground
</LI>
</UL>
</LI>
<LI><SPAN CLASS="textbf">Parameters</SPAN> : Parameters are given in the map <code>param</code>.
<UL>
<LI><SPAN CLASS="textbf">nbit</SPAN> (mandatory) : Defines the size of the generator
</LI>
<LI><SPAN CLASS="textbf">physical</SPAN> (optional, default value : False) : In order to generate a layout
</LI>
</UL>
</LI>
<LI><SPAN CLASS="textbf">How it works</SPAN> :
<UL>
<LI>If the <code>op[0]</code> signal is set to <code>one</code>, performs a right shift, performs a left shift otherwise.
</LI>
<LI>If the <code>op[1]</code> signal is set to <code>one</code>, performs an arithmetic shift (only meaningful in case of a right shift).
</LI>
<LI>shamt : specifies the shift amount. The width of this signal (<code>Y</code>) is computed from the operator's width : <code>Y = ceil(log2(n)) </code>- 1
</LI>
</UL>
</LI>
<LI><SPAN CLASS="textbf">Example</SPAN> :
<PRE>
from stratus import *
class inst_shifter ( Model ) :
def Interface ( self ) :
self.instop = SignalIn ( "instop", 2 )
self.instshamt = SignalIn ( "instshamt", 2 )
self.insti = SignalIn ( "insti", 4 )
self.insto = SignalOut ( "insto", 4 )
self.vdd = VddIn ( "vdd" )
self.vss = VssIn ( "vss" )
def Netlist ( self ) :
Generate ( 'DpgenShifter', 'shifter_4'
, param = { 'nbit' : 4
, 'physical' : True
}
)
self.I = Inst ( 'shifter_4', 'inst'
, map = { 'op' : self.instop
, 'shamt' : self.instshamt
, 'i' : self.insti
, 'o' : self.insto
, 'vdd' : self.vdd
, 'vss' : self.vss
}
)
def Layout ( self ) :
Place ( self.I, NOSYM, Ref(0, 0) )
</PRE>
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Sophie B<small>ELLOEIL</small><br>20051116.1
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