Arithmetical operations

Description

Most common arithmetic operators can be instantiated without the Inst constructor.

List

Arithmetical operators are listed below :

• Addition : q <= i0 + i1
• Substraction : q <= i0 - i1
• Multiplication : q <= i0 * i1
• Division : q <= i0 / i1

Generators to instantiate

One can choose the generator to be used. Some methods are applied to the cell and set the generator used when using overloard. Methods are :

• SetAdd (for addition and substraction)
• SetMult
• SetDiv

The generators used by default are :

• Addition : Slansky adder
• Substraction : Slansky adder + inversor + cin = '1'
• Multiplication : CA2 multiplier (signed, modified booth/Wallace tree)
• Division : not available yet

Example

class essai ( Model ) :

  def Interface ( self ) :
    self.A = SignalIn  ( "a", 4 )
    self.B = SignalIn  ( "b", 4 )
    
    self.S = SignalOut ( "s", 4 )
    
    self.T = SignalOut ( "t", 8 )

    self.vdd = VddIn  ( "vdd" )
    self.vss = VssIn  ( "vss" )
	
  def Netlist ( self ) :

    self.S <= self.A + self.B

    self.T <= self.A * self.B

Errors

Some errors may occur :

• [Stratus ERROR] + : the nets must have the same lenght.
  When one uses arithmetic expressions, one has to check that the sizes of both nets are equivalent.
• [Stratus ERROR] : there is no alim.
  The cell being created does not have the alimentation nets. The instanciation is impossible.

See Also

Introduction Netlist Instanciation of a multiplexor Instanciation of a shifter Instanciation of a register Instanciation of constants Boolean operations Comparison operations