test lib at c level.

lib/util.dart

@@ -15,14 +15,23 @@ class Uint8FlexList extends ListBase<Uint8> {
   set list(List<Uint8> l) {
     _list.removeWhere((element) => true);
     _list.addAll(l);
+    Pointer<Uint8> p = pointer;
     pointer = calloc<Uint8>(l.length);
-    _list.forEach((element) {
-      pointer[_list.indexOf(element)] = element as int;
-    });
+    for (int i = 0; i < _list.length; ++i) {
+      pointer[i] = _list[i] as int;
+    }
+    calloc.free(p);
   }
 
   @override
   void operator []=(int index, Uint8 value) {
+    if (index > _list.length) {
+      // resize the pointer
+      pointer = calloc<Uint8>(index - 1);
+      for (int i = 0; i < _list.length; ++i) {
+        pointer[i] = _list[i] as int;
+      }
+    }
     _list[index] = value;
     pointer[index] = value as int;
   }
@@ -37,14 +46,11 @@ class Uint8FlexList extends ListBase<Uint8> {
 
   static fromList(List<Uint8> l) {
     final l2 = Uint8FlexList();
+    l2.list = l;
+    return l2;
   }
 }
 
-Pointer<Uint8> readUint8Ptr(File file) {
-  final l = file.readAsBytesSync().cast();
-  final dataPointer = calloc<Uint8>(l.length);
-  for (int i = 0; i < l.length; ++i) {
-    dataPointer[i] = l[i];
-  }
-  return dataPointer;
+Uint8FlexList readUint8Ptr(File file) {
+  return Uint8FlexList.fromList(file.readAsBytesSync().cast());
 }