diff --git a/Makefile b/Makefile
index b597c85..0d19a87 100644
--- a/Makefile
+++ b/Makefile
@@ -21,7 +21,7 @@ vcd_spans.c \
 # the version here has a prepended underscore
 # all lines must have trailing comma
 EXPORT_STRING = \
-# "_somefn", \
+"_execute", \
 # "_int_sqrt", \
 # "_pass_write_fn", \
 # "_get_saved_node_count", \
diff --git a/lib/wrapper.js b/lib/wrapper.js
index e7c4f98..1318bf1 100644
--- a/lib/wrapper.js
+++ b/lib/wrapper.js
@@ -11,18 +11,60 @@ module.exports = () => {
   // let total = 0;
   // let start = 0;
 
+  const c = {};
+
   const wasm = require('../out/vcd.js');
 
+  let bindCallback;
 
-  let start = async() => {
+  const bindCWrap = () => {
+    const w = wasm.cwrap;
+    c.execute = w('execute', 'void', ['number', 'number', 'number', 'number']);
+  };
+
+  const start = async() => {
     await _waitForStart(wasm);
+    bindCWrap();
+    bindCallback();
   }
 
+  // gets a string from a c heap pointer and length
+  const getString = (name,len) => {
+     const view = wasm.HEAPU8.subarray(name, name+len);
+
+     let string = '';
+     for (let i = 0; i < len; i++) {
+        string += String.fromCharCode(view[i]);
+     }
+     return string;
+  }
+
+  let boundSet;
+
+  // wasm.addFunction can't be called until after
+  // start finishes
+  bindCallback = () => {
+   boundSet = wasm.addFunction(function(name, len, value) {
+
+
+    let prop = getString(name, len);
+
+     console.log(`setting ${prop} to ${value}`);
+
+
+     // vsi means returns void accepts a string and int
+   }, 'viii');
+  };
+
   return {
     start,
+    c,
     log: () => {
       console.log(wasm);
     },
+    execute: () => {
+      c.execute(0,0,boundSet,0);
+    },
     onB: (time, cmd) => {
       
     },
diff --git a/test/wasm.js b/test/wasm.js
index ec52819..9000923 100644
--- a/test/wasm.js
+++ b/test/wasm.js
@@ -22,6 +22,10 @@ describe('basic', () => {
 
     console.log("test");
 
+    // wrapper.c.execute('hello world');
+
+    wrapper.execute();
+
     // console.log(wrapper.log());
 
 
diff --git a/wasm_main.cpp b/wasm_main.cpp
index 84e776b..c68b475 100644
--- a/wasm_main.cpp
+++ b/wasm_main.cpp
@@ -10,19 +10,58 @@ using namespace std;
 static struct vcd_parser_s* state;
 
 
-static void init(void) {
+// returns context
+int init(void) {
   state = (struct vcd_parser_s*) malloc(sizeof *state);
 
   const int32_t error = vcd_parser_init(state);
   if (error) {
     cout << "ERROR: " << error << "\n";
-    return;
+    return -1;
   }
+
+  return 0;
 }
 
 int main(void) {
   cout << "main()\n";
-  init();
   return 0;
 }
 
+
+/// Typedef used as part of c->js call
+typedef void externalJsMethodOne(const int sz);
+typedef void externalJsMethodTwo(const char*, const uint64_t time, const uint8_t command, const int dnc0, const int dnc1);
+
+
+typedef int  externalJsGetProperty(const char* name);
+typedef void externalJsSetProperty(const char* name, const size_t len, const int value);
+
+
+/// function pointer for c->js
+static externalJsMethodOne* externalOne = 0;
+static externalJsMethodTwo* externalTwo = 0;
+static externalJsSetProperty* set_property = 0;
+static externalJsGetProperty* get_property = 0;
+
+
+
+extern "C" {
+
+void execute(
+  externalJsMethodOne* f1,
+  externalJsMethodTwo* f2,
+  externalJsSetProperty* sfn,
+  externalJsGetProperty* gfn
+  ) {
+
+  // cout << "execute got " << p << "\n";
+  cout << "execute " << (int)sfn << "\n";
+  set_property = sfn;
+
+  set_property("foo", strlen("foo"), 4);
+  
+
+}
+
+} // extern C
\ No newline at end of file