vpr: base: atom_netlist_utils: add support for printing netlist with falling edge clocked FFs as blif

Signed-off-by: Pawel Czarnecki <pczarnecki@antmicro.com>

Author: lpawelcz

vpr/src/base/atom_netlist_utils.cpp

@@ -189,8 +189,14 @@ void print_netlist_as_blif(FILE* f, const AtomNetlist& netlist) {
                 clk_net = make_unconn(unconn_count, PinType::SINK);
             }
 
-            //Latch type: VPR always assumes rising edge
-            auto type = "re";
+            //Latch type
+            auto type = "xy";
+            if ((blk_model->name == std::string(MODEL_LATCH)) && (blk_model->inputs[1].is_clock))
+                if (blk_model->inputs[1].trigg_edge == TriggeringEdge::FALLING_EDGE)
+                    type = "fe";
+                else
+                    //Always assume rising edge
+                    type = "re";
 
             //Latch initial value
             int init_val = 3; //Unkown or unspecified