Add an external array type to support typed arrays.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index a5676a34f7f26cb853a2008a1d241f6281f5f82b..9b2d1247fb3aafa2fca3cb86c3624c55a7555ca1 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -2763,6 +2763,117 @@ class ImmutableArray : public Array {
 };
 
 
+class ExternalArray : public Instance {
+ public:
+  intptr_t Length() const {
+    ASSERT(!IsNull());
+    return Smi::Value(raw_ptr()->length_);
+  }
+
+  int8_t Int8At(intptr_t index) const {
+    return *Addr<int8_t>(index);
+  }
+  void SetInt8At(intptr_t index, int8_t value) const {
+    *Addr<int8_t>(index) = value;
+  }
+
+  uint8_t Uint8At(intptr_t index) const {
+    return *Addr<uint8_t>(index);
+  }
+  void SetUint8At(intptr_t index, uint8_t value) const {
+    *Addr<uint8_t>(index) = value;
+  }
+
+  int16_t Int16At(intptr_t index) const {
+    return *Addr<int16_t>(index);
+  }
+  void SetInt16At(intptr_t index, int16_t value) const {
+    *Addr<int16_t>(index) = value;
+  }
+
+  uint16_t Uint16At(intptr_t index) const {
+    return *Addr<uint16_t>(index);
+  }
+  void SetUint16At(intptr_t index, uint16_t value) const {
+    *Addr<uint16_t>(index) = value;
+  }
+
+  int32_t Int32At(intptr_t index) const {
+    return *Addr<int32_t>(index);
+  }
+  void SetInt32At(intptr_t index, int32_t value) const {
+    *Addr<int32_t>(index) = value;
+  }
+
+  uint32_t Uint32At(intptr_t index) const {
+    return *Addr<uint32_t>(index);
+  }
+  void SetUint32At(intptr_t index, uint32_t value) const {
+    *Addr<uint32_t>(index) = value;
+  }
+
+  int64_t Int64At(intptr_t index) const {
+    return *Addr<int64_t>(index);
+  }
+  void SetInt64At(intptr_t index, int64_t value) const {
+    *Addr<int64_t>(index) = value;
+  }
+
+  uint64_t Uint64At(intptr_t index) const {
+    return *Addr<uint64_t>(index);
+  }
+  void SetUint64At(intptr_t index, uint64_t value) const {
+    *Addr<uint64_t>(index) = value;
+  }
+
+  float Float32At(intptr_t index) const {
+    return *Addr<float>(index);
+  }
+  void SetFloat32At(intptr_t index, float value) const {
+    *Addr<float>(index) = value;
+  }
+
+  double Float64At(intptr_t index) const {
+    return *Addr<double>(index);
+  }
+  void SetFloat64At(intptr_t index, double value) const {
+    *Addr<double>(index) = value;
+  }
+
+  virtual bool Equals(const Instance& other) const;
+
+  static intptr_t InstanceSize() {
+    return RoundedAllocationSize(sizeof(RawExternalArray));
+  }
+
+  static RawExternalArray* New(uint8_t* data,
+                               intptr_t len,
+                               Heap::Space space = Heap::kNew);
+
+ private:
+  template<typename T>
+  T* Addr(intptr_t index) const {
+    intptr_t byte_start = index / sizeof(T);

[siva, 2011/11/02 17:05:31]

is this right:

for instance Addr<int32_t>(1) should produce an address
of &(raw_ptr()->data_[4]); which would be index * sizeof(T)

[cshapiro, 2011/11/04 18:16:21]

No, it was not.  I fixed this in the more recent patch set.

+    intptr_t byte_end = byte_start + sizeof(T);
+    // TODO(iposva): Determine if we should throw an exception here.
+    ASSERT((byte_start >= 0) && (byte_end < Length()));
+    uint8_t* addr = &raw_ptr()->data_[byte_start];
+    return reinterpret_cast<T*>(addr);
+  }
+
+  void SetLength(intptr_t value) {
+    raw_ptr()->length_ = Smi::New(value);
+  }
+
+  void SetData(uint8_t* data) const {
+    raw_ptr()->data_ = data;
+  }
+
+  HEAP_OBJECT_IMPLEMENTATION(ExternalArray, Instance);
+  friend class Class;
+};
+
+
 class Closure : public Instance {
  public:
   RawFunction* function() const { return raw_ptr()->function_; }