diff --git a/src/pcf.rs b/src/pcf.rs
index ac4e49b..74aced0 100644
--- a/src/pcf.rs
+++ b/src/pcf.rs
@@ -25,7 +25,7 @@ impl PcfFile {
     }
     pub fn pinvec(&self, name: &str, index: u32) -> Option<u32> {
         // construct a name of the form <name>[<index>]
-        let realname = format!("{name}[{index}]", name = name, index = index);
+        let realname = format!("{name}[{index}]");
         self.map.get(&realname).cloned()
     }
 }
diff --git a/src/yosys_parser.rs b/src/yosys_parser.rs
index 869990c..8fb39d6 100644
--- a/src/yosys_parser.rs
+++ b/src/yosys_parser.rs
@@ -1,4 +1,5 @@
 use crate::gal::Pin;
+use crate::pcf::PcfFile;
 use serde::{de::Error, Deserialize, Deserializer, Serialize};
 use serde_with::{serde_as, BoolFromInt};
 use std::collections::HashMap;
@@ -181,7 +182,7 @@ pub enum AnyCell {
 // we look it up by id. But we can also match based on type.
 type Netlist = HashMap<String, AnyCell>;
 
-// we know that the yosys moduel uses unique names. well at least it should.
+// we know that the yosys module uses unique names. well at least it should.
 
 impl YosysDoc {
     pub fn to_netlist(&self) -> Netlist {
@@ -202,7 +203,6 @@ impl YosysDoc {
                     }
                 }
             }
-
             for (name, cell) in &m.cells {
                 println!("Found Cell {}", name);
                 match cell {
@@ -216,6 +216,37 @@ impl YosysDoc {
     }
 }
 
-fn get_netlist_nodes<T>(nl: &Netlist) -> Vec<&T> {
-    Vec::new()
+/* constraint mapping pipeline
+ * take yosys document -> look at top-level module ports
+ * use constraints pcf file to map. This creates a HashMap<Net, u32> for mapping nets to pins.
+ * only do this for *ports*, not cells.
+ */
+
+enum PortValue {
+    Single(u32),
+    Register(Vec<u32>),
+}
+
+/*
+ * this fn 
+ */
+fn port_lookup(name: &str, cell: &AnyCell, pcf: &PcfFile) -> Option<PortValue> {
+    match cell {
+        AnyCell::Input(p) => {
+            if p.bits.len() == 1 {
+                pcf.pin(name).map(PortValue::Single)
+            } else {
+                // check upto
+                if p.upto {
+                    for (idx, net) in p.bits.iter().enumerate() {
+                    }
+                    None
+                } else {
+                    None
+                }
+            }
+        },
+
+        _ => None
+    }
 }
diff --git a/tests/pcf_test.rs b/tests/pcf_test.rs
index df06900..1137db4 100644
--- a/tests/pcf_test.rs
+++ b/tests/pcf_test.rs
@@ -25,7 +25,7 @@ set_io vec[1] 3";
 
 #[test]
 #[should_panic]
-fn test_invalid() {
+fn test_name_collision() {
     let test = "
 set_io scalar 1
 set_io scalar 2";