dff2dffe - transform $dff cells to $dffe cells
dff2dffe [options] [selection]
This pass transforms $dff cells driven by a tree of multiplexers with one or
more feedback paths to $dffe cells. It also works on gate-level cells such as
$_DFF_P_, $_DFF_N_ and $_MUX_.
operate in the opposite direction: replace $dffe cells with combinations
of $dff and $mux cells. the options below are ignore in unmap mode.
-direct <internal_gate_type> <external_gate_type>
map directly to external gate type. <internal_gate_type> can
be any internal gate-level FF cell (except $_DFFE_??_). the
<external_gate_type> is the cell type name for a cell with an
identical interface to the <internal_gate_type>, except it
also has an high-active enable port 'E'.
Usually <external_gate_type> is an intermediate cell type
that is then translated to the final type using 'techmap'.
like -direct for all DFF cell types matching the expression.
this will use $__DFFE_* as <external_gate_type> matching the
internal gate type $_DFF_*_, and $__DFFSE_* for those matching
$_DFFS_*_, except for $_DFF_[NP]_, which is converted to