v8 typed arrays: add DataView type

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index d0958eef29a0faa736980f8b8bd23887da101375..e425302a7a10031a1f4249c0d481a85f1efa738d 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -682,6 +682,7 @@ bool Object::IsBoolean() {
 
 TYPE_CHECKER(JSArray, JS_ARRAY_TYPE)
 TYPE_CHECKER(JSArrayBuffer, JS_ARRAY_BUFFER_TYPE)
+TYPE_CHECKER(JSDataView, JS_DATA_VIEW_TYPE)
 TYPE_CHECKER(JSTypedArray, JS_TYPED_ARRAY_TYPE)
 TYPE_CHECKER(JSRegExp, JS_REGEXP_TYPE)
 
@@ -1644,6 +1645,8 @@ int JSObject::GetHeaderSize() {
       return JSArray::kSize;
     case JS_ARRAY_BUFFER_TYPE:
       return JSArrayBuffer::kSize;
+    case JS_DATA_VIEW_TYPE:
+      return JSDataView::kSize;
     case JS_TYPED_ARRAY_TYPE:
       return JSTypedArray::kSize;
     case JS_SET_TYPE:
@@ -2548,6 +2551,7 @@ CAST_ACCESSOR(JSBuiltinsObject)
 CAST_ACCESSOR(Code)
 CAST_ACCESSOR(JSArray)
 CAST_ACCESSOR(JSArrayBuffer)
+CAST_ACCESSOR(JSDataView)
 CAST_ACCESSOR(JSTypedArray)
 CAST_ACCESSOR(JSRegExp)
 CAST_ACCESSOR(JSProxy)
@@ -5321,6 +5325,45 @@ void JSArrayBuffer::set_is_external(bool value) {
 }
 
 
+ACCESSORS(JSDataView, buffer, Object, kBufferOffset)
+ACCESSORS(JSDataView, byte_offset, Object, kByteOffsetOffset)
+ACCESSORS(JSDataView, byte_length, Object, kByteLengthOffset)
+
+
+template <typename TypeName>
+TypeName JSDataView::Get(size_t byte_offset, bool little_endian) {
+  size_t byte_length = static_cast<size_t>(this->byte_length()->Number());

[Dmitry Lomov (no reviews), 2013/06/03 13:09:04]

Use NumberToSize

[bnoordhuis, 2013/06/03 13:48:12]

I copied that from ArrayBuffer actually, to keep friction as low as possible.
:-)

Want me to update that as well? 

[Dmitry Lomov (no reviews), 2013/06/03 14:42:49]

Use NumberToSize here, do not update usages in code you have not touched (to
minimize churn)

+  if (byte_offset + sizeof(TypeName) > byte_length) return 0;
+  if (byte_offset + sizeof(TypeName) < byte_offset) return 0;  // Overflow.
+  Handle<JSArrayBuffer> buffer(JSArrayBuffer::cast(this->buffer()));
+  const char* data = static_cast<const char*>(buffer->backing_store()) +
+                     static_cast<size_t>(this->byte_offset()->Number()) +
+                     byte_offset;
+  TypeName value;
+  OS::MemCopy(&value, data, sizeof(value));
+  if (sizeof(TypeName) > 1 && little_endian ^ IsLittleEndian()) {
+    Swizzle(&value);
+  }
+  return value;
+}
+
+
+template <typename TypeName>
+void JSDataView::Set(size_t byte_offset, TypeName value, bool little_endian) {
+  size_t byte_length = static_cast<size_t>(this->byte_length()->Number());

[Dmitry Lomov (no reviews), 2013/06/03 13:09:04]

Use NumberToSize.

+  if (byte_offset + sizeof(TypeName) > byte_length) return;
+  if (byte_offset + sizeof(TypeName) < byte_offset) return;  // Overflow.
+  Handle<JSArrayBuffer> buffer(JSArrayBuffer::cast(this->buffer()));
+  char* data = static_cast<char*>(buffer->backing_store()) +
+               static_cast<size_t>(this->byte_offset()->Number()) +
+               byte_offset;
+  if (sizeof(TypeName) > 1 && little_endian ^ IsLittleEndian()) {
+    Swizzle(&value);
+  }
+  OS::MemCopy(data, &value, sizeof(value));
+}
+
+
 ACCESSORS(JSTypedArray, buffer, Object, kBufferOffset)
 ACCESSORS(JSTypedArray, byte_offset, Object, kByteOffsetOffset)
 ACCESSORS(JSTypedArray, byte_length, Object, kByteLengthOffset)