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..beb4fafad9c8af1f8e3f4e78f5bb1bf38151d593 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -5034,6 +5034,11 @@ class TypedData : public Instance {
     return ElementSizeInBytes(cid);
   }
 
+  intptr_t ElementType() const {
+    intptr_t cid = raw()->GetClassId();
+    return ElementType(cid);

[kustermann, 2013/04/16 17:26:04]

It is not the nicest thing that these functions return 'intptr_t'.

Alternatively, I could add a field to TypedData/ExternalTypedData which stores
it's "TypedDataType".

[Vyacheslav Egorov (Google), 2013/04/17 11:41:56]

Why not introduce an enum:

enum TypeDataElementType {
#define V(name) k##name##Element,
}

and then use it here? (cast result to it). 

[Vyacheslav Egorov (Google), 2013/04/17 12:55:27]

I meant:

enum TypeDataElementType {
#define V(name) k##name##Element,
CLASS_LIST_TYPED_DATA(V)
#undef V
}

On 2013/04/17 11:41:56, Vyacheslav Egorov (Google) wrote:

[kustermann, 2013/04/18 13:57:57]

Done.

+  }
+
   intptr_t LengthInBytes() const {
     intptr_t cid = raw()->GetClassId();
     return (ElementSizeInBytes(cid) * Length());
@@ -5086,6 +5091,11 @@ class TypedData : public Instance {
     return element_size[class_id - kTypedDataInt8ArrayCid];
   }
 
+  static intptr_t ElementType(intptr_t class_id) {
+    ASSERT(RawObject::IsTypedDataClassId(class_id));
+    return class_id - kTypedDataInt8ArrayCid;
+  }
+
   static intptr_t MaxElements(intptr_t class_id) {
     ASSERT(RawObject::IsTypedDataClassId(class_id));
     return (kSmiMax / ElementSizeInBytes(class_id));
@@ -5134,6 +5144,11 @@ class ExternalTypedData : public Instance {
     return ElementSizeInBytes(cid);
   }
 
+  intptr_t 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 +5202,11 @@ class ExternalTypedData : public Instance {
     return TypedData::element_size[class_id - kExternalTypedDataInt8ArrayCid];
   }
 
+  static intptr_t ElementType(intptr_t class_id) {
+    ASSERT(RawObject::IsExternalTypedDataClassId(class_id));
+    return class_id - kExternalTypedDataInt8ArrayCid;
+  }
+
   static intptr_t MaxElements(intptr_t class_id) {
     ASSERT(RawObject::IsExternalTypedDataClassId(class_id));
     return (kSmiMax / ElementSizeInBytes(class_id));