diff --git a/lib/wrapper.js b/lib/wrapper.js
index 4a03171..a1f24d9 100644
--- a/lib/wrapper.js
+++ b/lib/wrapper.js
@@ -19,7 +19,7 @@ module.exports = () => {
 
   const bindCWrap = () => {
     const w = wasm.cwrap;
-    c.execute = w('execute', 'void',   ['number', 'number', 'number', 'number', 'number', 'string']);
+    c.execute = w('execute', 'number', ['number', 'number', 'number', 'number', 'number', 'string']);
     c.init    = w('init',    'number', ['number', 'number', 'number', 'number']);
   };
 
diff --git a/test/wasm.js b/test/wasm.js
index 8ce9889..f55b022 100644
--- a/test/wasm.js
+++ b/test/wasm.js
@@ -35,7 +35,7 @@ describe('basic', () => {
 
     wrapper.execute();
 
-    expect(info.foo).to.equal(10);
+    // expect(info.foo).to.equal(10);
     // console.log(wrapper.log());
 
 
diff --git a/test/wasmdump.js b/test/wasmdump.js
new file mode 100644
index 0000000..95dbdcf
--- /dev/null
+++ b/test/wasmdump.js
@@ -0,0 +1,124 @@
+'use strict';
+
+const expect = require('chai').expect;
+// const lib = require('../lib/index.js');
+const lib = require('../lib/wrapper.js')();
+
+describe('dump', () => {
+
+  before(() => {
+    return lib.start();
+  });
+
+  it('simple', done => {
+    const inst = lib.parser();
+    const dump = [];
+    ['"}G', '{u', 'u)'] // array of all signal ids
+      .map(id =>
+        inst.change.on(id, (time, cmd, value, mask) => {
+          dump.push({
+            id,
+            time,
+            cmd,
+            value,
+            mask
+          });
+        })
+      );
+
+    inst.on('finish', () => {
+      expect(inst.getTime()).to.eq(316n);
+      expect(dump).to.deep.eq([
+        { id: '"}G', time: 100, cmd: 14, value: 0n, mask: 0n },
+        { id: '"}G', time: 200, cmd: 15, value: 1n, mask: 0n },
+        { id: '{u', time: 200, cmd: 19, value: 0xf0f0f0f0f0f0f0f0n, mask: 0xff00ff00ff00ff00n },
+        { id: '"}G', time: 300, cmd: 14, value: 0n, mask: 0n },
+        { id: '{u', time: 300, cmd: 19, value: 0xf000000000000000n, mask: 0n },
+        { id: '{u', time: 301, cmd: 19, value: 0x0f00000000000000n, mask: 0n },
+        { id: '{u', time: 302, cmd: 19, value: 0x00f0000000000000n, mask: 0n },
+        { id: '{u', time: 303, cmd: 19, value: 0x000f000000000000n, mask: 0n },
+        { id: '{u', time: 304, cmd: 19, value: 0x0000f00000000000n, mask: 0n },
+        { id: '{u', time: 305, cmd: 19, value: 0x00000f0000000000n, mask: 0n },
+        { id: '{u', time: 306, cmd: 19, value: 0x000000f000000000n, mask: 0n },
+        { id: '{u', time: 307, cmd: 19, value: 0x0000000f00000000n, mask: 0n },
+        { id: '{u', time: 308, cmd: 20, value: 0x00000000f0000000n, mask: 0n },
+        { id: '{u', time: 309, cmd: 19, value: 0x000000000f000000n, mask: 0n },
+        { id: '{u', time: 310, cmd: 19, value: 0x0000000000f00000n, mask: 0n },
+        { id: '{u', time: 311, cmd: 19, value: 0x00000000000f0000n, mask: 0n },
+        { id: '{u', time: 312, cmd: 19, value: 0x000000000000f000n, mask: 0n },
+        { id: '{u', time: 313, cmd: 19, value: 0x0000000000000f00n, mask: 0n },
+        { id: '{u', time: 314, cmd: 19, value: 0x00000000000000f0n, mask: 0n },
+        { id: '{u', time: 315, cmd: 19, value: 0x000000000000000fn, mask: 0n },
+        { id: '"}G', time: 316, cmd: 15, value: 1n, mask: 0n },
+      ])
+      // console.log(dump);
+      done();
+    });
+
+    inst.write(`
+$version Generated by VerilatedVcd $end
+$date Wed Sep 18 22:59:07 2019
+ $end
+$timescale   1ns $end
+
+  $scope   module   top    $end
+    $var wire  1 "}G clock $end
+    $scope module leaf $end
+      $var wire 64 {u counter [63:0] $end
+    $upscope $end
+    $scope module fruit $end
+      $var wire 4 u) point [3:0] $end
+    $upscope $end
+  $upscope $end
+
+  $enddefinitions $end
+#100
+0"}G
+#200
+1"}G
+bzzzzxxxx11110000ZZZZXXXX11110000zzzzxxx`);
+
+// break in the middle of the number scan
+
+     inst.write(                       `x11110000zzzzxxxx11110000 {u
+#300
+0"}G
+b1111000000000000000000000000000000000000000000000000000000000000 {u
+#301
+b0000111100000000000000000000000000000000000000000000000000000000 {u
+#302
+b0000000011110000000000000000000000000000000000000000000000000000 {u
+#303
+b0000000000001111000000000000000000000000000000000000000000000000 {u
+#304
+b0000000000000000111100000000000000000000000000000000000000000000 {u
+#305
+b0000000000000000000011110000000000000000000000000000000000000000 {u
+#306
+b0000000000000000000000001111000000000000000000000000000000000000 {u
+#307
+b0000000000000000000000000000111100000000000000000000000000000000 {u
+#308
+B0000000000000000000000000000000011110000000000000000000000000000 {u
+#309
+b0000000000000000000000000000000000001111000000000000000000000000 {u
+#310
+b0000000000000000000000000000000000000000111100000000000000000000 {u
+#311
+b0000000000000000000000000000000000000000000011110000000000000000 {u
+#312
+b0000000000000000000000000000000000000000000000001111000000000000 {u
+#313
+b0000000000000000000000000000000000000000000000000000111100000000 {u
+#314
+b0000000000000000000000000000000000000000000000000000000011110000 {u
+#315
+b0000000000000000000000000000000000000000000000000000000000001111 {u
+#316
+1"}G
+`);
+    inst.end();
+  });
+});
+
+/* eslint-env mocha */
diff --git a/vcd_spans.c b/vcd_spans.c
index f872288..af0602d 100644
--- a/vcd_spans.c
+++ b/vcd_spans.c
@@ -11,6 +11,8 @@ typedef void* napi_env;
 #endif
 
 
+// #define LOGSPAN
+#define LOGSPAN printf("%s\n", __FUNCTION__);
 
 
 #define ASSERT(val, expr) \
@@ -62,6 +64,7 @@ int stringEq (
 }
 
 int commandSpan(vcd_parser_t* state, const unsigned char* p, const unsigned char* endp) {
+  LOGSPAN;
   napi_env env = state->napi_env;
 
   if (state->command == 5) { // $upscope
@@ -87,6 +90,7 @@ int commandSpan(vcd_parser_t* state, const unsigned char* p, const unsigned char
 }
 
 int scopeIdentifierSpan(vcd_parser_t* state, const unsigned char* p, const unsigned char* endp) {
+  LOGSPAN;
 #ifndef VCDWASM
   napi_env env = state->napi_env;
   // *(endp - 1) = 0; // FIXME NULL termination of ASCII string
@@ -104,6 +108,7 @@ int scopeIdentifierSpan(vcd_parser_t* state, const unsigned char* p, const unsig
 }
 
 int varSizeSpan(vcd_parser_t* state, const unsigned char* p, const unsigned char* endp) {
+  LOGSPAN;
   state->size = strtol((const char *)p, (char **)&endp, 10);
   return 0;
 }
diff --git a/wasm_main.cpp b/wasm_main.cpp
index f203312..057f011 100644
--- a/wasm_main.cpp
+++ b/wasm_main.cpp
@@ -88,33 +88,55 @@ int init(
 
 
 
-
-
-
-void execute(
+int32_t execute(
   const int context,
   externalJsMethodOne* f1,
   externalJsMethodTwo* f2,
   externalJsSetProperty* sfn,
   externalJsGetProperty* gfn,
-  char* chunk
+  char* p
   ) {
 
   // cout << "execute got " << p << "\n";
-  cout << "execute " << (int)sfn << " and got " << chunk << "\n";
+  cout << "execute " << (int)sfn << " and got " << p << "\n";
   bound_set_property = sfn;
   bound_get_property = gfn;
   externalOne = f1;
   externalTwo = f2;
 
-  set_property_int("foo", 10);
+  const size_t plen = strlen(p);
+
+  const int32_t error = vcd_parser_execute(state, p, p + plen);
+
+  return error;
+}
+
+
+
+// void execute(
+//   const int context,
+//   externalJsMethodOne* f1,
+//   externalJsMethodTwo* f2,
+//   externalJsSetProperty* sfn,
+//   externalJsGetProperty* gfn,
+//   char* chunk
+//   ) {
+
+//   // cout << "execute got " << p << "\n";
+//   cout << "execute " << (int)sfn << " and got " << chunk << "\n";
+//   bound_set_property = sfn;
+//   bound_get_property = gfn;
+//   externalOne = f1;
+//   externalTwo = f2;
+
+//   set_property_int("foo", 10);
   
 
-  int got = get_property("bar");
+//   int got = get_property("bar");
 
-  cout << "got " << got << " for bar\n";
+//   cout << "got " << got << " for bar\n";
 
-}
+// }
 
 int main(void) {
   cout << "main()\n";