diff --git a/simple/carry_cyinit_mux.tcl b/simple/carry_cyinit_mux.tcl
new file mode 100644
index 00000000..8d0d92e6
--- /dev/null
+++ b/simple/carry_cyinit_mux.tcl
@@ -0,0 +1,25 @@
+# set carry_cell [lindex [get_cells -hierarchical -filter {REF_NAME == CARRY4}] 0]
+
+proc get_carry_cyinit_mux_cfg {carry_cell} {
+	set cyinit_pin [get_pins -of_objects $carry_cell -filter {REF_PIN_NAME == CYINIT}]
+	set cyinit_net [get_nets -quiet -of_objects $cyinit_pin]
+
+	if {[string last "<const0>" $cyinit_net] > 0} { return "zero" }
+	if {[string last "<const1>" $cyinit_net] > 0} { return "one" }
+
+	set cin_pin [get_site_pins -of_objects [get_sites -of_objects $carry_cell] */CIN]
+	set cin_net [get_nets -quiet -of_objects $cin_pin]
+	if {"$cyinit_net" == "$cin_net"} { return "cin" }
+
+	set ax_pin [get_site_pins -of_objects [get_sites -of_objects $carry_cell] */AX]
+	set ax_net [get_nets -quiet -of_objects $ax_pin]
+	if {"$cyinit_net" == "$ax_net"} { return "ax" }
+
+	return "unknown"
+}
+
+proc list_carry_cyinit_mux_cfg {} {
+	foreach carry_cell [get_cells -hierarchical -filter {REF_NAME == CARRY4}] {
+		puts "[get_bels -of_objects $carry_cell] [get_carry_cyinit_mux_cfg $carry_cell]"
+	}
+}