Fast copy between TypedData and ExternalTypedData

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index a81aaa05a37bbc548f7dadf2e98b2bf88b881ce6..d06c639964de200d79b1793feeefdb6b3d24b061 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -5034,6 +5034,12 @@ class TypedData : public Instance {
     return ElementSizeInBytes(cid);
   }
 
+
+  TypeDataElementType ElementType() const {
+    intptr_t cid = raw()->GetClassId();
+    return ElementType(cid);
+  }
+
   intptr_t LengthInBytes() const {
     intptr_t cid = raw()->GetClassId();
     return (ElementSizeInBytes(cid) * Length());
@@ -5086,6 +5092,12 @@ class TypedData : public Instance {
     return element_size[class_id - kTypedDataInt8ArrayCid];

[siva, 2013/04/19 17:38:40]

you could use your new ElementType() here instead of
class_id - kTypedDataInt8ArrayCid

[kustermann, 2013/04/19 19:21:54]

Done.

[kustermann, 2013/04/19 19:21:54]

Done.

   }
 
+  static TypeDataElementType ElementType(intptr_t class_id) {
+    ASSERT(RawObject::IsTypedDataClassId(class_id));
+    return static_cast<TypeDataElementType>(
+        class_id - kTypedDataInt8ArrayCid);
+  }
+
   static intptr_t MaxElements(intptr_t class_id) {
     ASSERT(RawObject::IsTypedDataClassId(class_id));
     return (kSmiMax / ElementSizeInBytes(class_id));
@@ -5134,6 +5146,11 @@ class ExternalTypedData : public Instance {
     return ElementSizeInBytes(cid);
   }
 
+  TypeDataElementType ElementType() const {
+    intptr_t cid = raw()->GetClassId();
+    return ElementType(cid);
+  }
+
   intptr_t LengthInBytes() const {
     intptr_t cid = raw()->GetClassId();
     return (ElementSizeInBytes(cid) * Length());
@@ -5187,6 +5204,12 @@ class ExternalTypedData : public Instance {
     return TypedData::element_size[class_id - kExternalTypedDataInt8ArrayCid];

[siva, 2013/04/19 17:38:40]

Ditto comment about using the new ElementType

[kustermann, 2013/04/19 19:21:54]

Done.

   }
 
+  static TypeDataElementType ElementType(intptr_t class_id) {
+    ASSERT(RawObject::IsExternalTypedDataClassId(class_id));
+    return static_cast<TypeDataElementType>(
+        class_id - kExternalTypedDataInt8ArrayCid);
+  }
+
   static intptr_t MaxElements(intptr_t class_id) {
     ASSERT(RawObject::IsExternalTypedDataClassId(class_id));
     return (kSmiMax / ElementSizeInBytes(class_id));
@@ -5228,6 +5251,28 @@ class ExternalTypedData : public Instance {
 };
 
 
+template <typename DstType, typename SrcType>
+void TypedArrayCopyData(const DstType& dst, intptr_t dst_offset_in_bytes,
+                        const SrcType& src, intptr_t src_offset_in_bytes,
+                        intptr_t length_in_bytes) {
+  ASSERT(dst.ElementType() == src.ElementType());
+  ASSERT(Utils::RangeCheck(src_offset_in_bytes,
+                           length_in_bytes,
+                           src.LengthInBytes()));
+  ASSERT(Utils::RangeCheck(dst_offset_in_bytes,
+                           length_in_bytes,
+                           dst.LengthInBytes()));
+  {
+    NoGCScope no_gc;
+    if (length_in_bytes > 0) {
+      memmove(dst.DataAddr(dst_offset_in_bytes),
+              src.DataAddr(src_offset_in_bytes),
+              length_in_bytes);
+    }
+  }
+}

[siva, 2013/04/19 17:38:40]

Why not make this the static function of class TypedData.
i.e:

class TypedData {
  .....
  .....
  template<typename DstType, typename SrcType>
  static void Copy(const DstType& dst, intptr_t dst_offset_in_bytes,
                   const SrcType& src, intptr_t src_offset_in_bytes,
                   intptr_t length_in_bytes) {
    add the code you have in TypedArrayCopyData here....
  }
  ....
  ....
};

Get rid of the Copy function in ExternalTypedData, everybody would use the
templatized copy function you define above.

[kustermann, 2013/04/19 19:21:54]

Done.

+
+
 class TypedDataView : public AllStatic {
  public:
   static intptr_t ElementSizeInBytes(const Instance& view_obj) {