Need to add new CellSymbols

Model2 Model needs to add new CellSymbols for correctly translations from RTLIL (Yosys):

• Unary operators:

  -- $slice

  -- $neg (negotiate) ((-A))

  -- $pos (positive) ((+A)) (((right now translates such as BUF)))

  -- $reduce_or OR $reduce_bool ((|A)) (((same functions)))

  -- $reduce_and ((&A))

  -- $reduce_xor ((^A))

  -- $reduce_xnor ((~^A))

• Binary operators:

  -- $shl (shift left) ((A << B))

  -- $shr (shift right) ((A >> B))

  -- $sshl (arithmetic shift left) ((A <<< B))

  -- $sshr (arithmetic shift right) ((A >>> B))

  -- $eqx (A === B)

  -- $nex (A !== B)

  -- $pow (A ** B)

  -- $concat(A | B)

  -- $shiftx

  -- $divfloor (flooring division)

  -- $modfloor (flooring module)

• Ternary operators:

  -- pmux

• Consequent logic:

  -- $sdff (dff with synchronous reset)

  -- $sdffe (dff with synchronous reset and enable) ((reset over enable))

  -- $aldff (dff with with asynchronous load)

  -- $aldffe (dff with with asynchronous load and enable) ((reset over enable))

  -- $aldffce (dff with with asynchronous load and enable) ((enable over reset))

  -- $dffsr (dff asynchronous set and reset)

  -- $dffsre (dff asynchronous set and reset and enable) ((reset over enable))

  -- $sr (Set-Clear latch)

  -- $dlatchsr (LATCH with set and reset)

  -- $adlatch (LATCH with reset)

  -- $dffe (dff with enable)

  -- $adffe (DFFrs with enable)

  For more details about the cells: https://yosys.readthedocs.io/\_/downloads/en/latest/pdf/ (pp. 154-157).