ART: Move DexCache arrays to native.

This CL has a companion CL in libcore/
    https://android-review.googlesource.com/162985

Change-Id: Icbc9e20ad1b565e603195b12714762bb446515fa
diff --git a/runtime/utils/dex_cache_arrays_layout.h b/runtime/utils/dex_cache_arrays_layout.h
new file mode 100644
index 0000000..d50be5a
--- /dev/null
+++ b/runtime/utils/dex_cache_arrays_layout.h
@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_UTILS_DEX_CACHE_ARRAYS_LAYOUT_H_
+#define ART_RUNTIME_UTILS_DEX_CACHE_ARRAYS_LAYOUT_H_
+
+namespace art {
+
+/**
+ * @class DexCacheArraysLayout
+ * @details This class provides the layout information for the type, method, field and
+ * string arrays for a DexCache with a fixed arrays' layout (such as in the boot image),
+ */
+class DexCacheArraysLayout {
+ public:
+  // Construct an invalid layout.
+  DexCacheArraysLayout()
+      : /* types_offset_ is always 0u */
+        pointer_size_(0u),
+        methods_offset_(0u),
+        strings_offset_(0u),
+        fields_offset_(0u),
+        size_(0u) {
+  }
+
+  // Construct a layout for a particular dex file.
+  DexCacheArraysLayout(size_t pointer_size, const DexFile* dex_file);
+
+  bool Valid() const {
+    return Size() != 0u;
+  }
+
+  size_t Size() const {
+    return size_;
+  }
+
+  size_t Alignment() const;
+
+  size_t TypesOffset() const {
+    return types_offset_;
+  }
+
+  size_t TypeOffset(uint32_t type_idx) const;
+
+  size_t TypesSize(size_t num_elements) const;
+
+  size_t TypesAlignment() const;
+
+  size_t MethodsOffset() const {
+    return methods_offset_;
+  }
+
+  size_t MethodOffset(uint32_t method_idx) const;
+
+  size_t MethodsSize(size_t num_elements) const;
+
+  size_t MethodsAlignment() const;
+
+  size_t StringsOffset() const {
+    return strings_offset_;
+  }
+
+  size_t StringOffset(uint32_t string_idx) const;
+
+  size_t StringsSize(size_t num_elements) const;
+
+  size_t StringsAlignment() const;
+
+  size_t FieldsOffset() const {
+    return fields_offset_;
+  }
+
+  size_t FieldOffset(uint32_t field_idx) const;
+
+  size_t FieldsSize(size_t num_elements) const;
+
+  size_t FieldsAlignment() const;
+
+ private:
+  static constexpr size_t types_offset_ = 0u;
+  const size_t pointer_size_;  // Must be first for construction initialization order.
+  const size_t methods_offset_;
+  const size_t strings_offset_;
+  const size_t fields_offset_;
+  const size_t size_;
+
+  static size_t Alignment(size_t pointer_size);
+
+  static size_t ElementOffset(size_t element_size, uint32_t idx);
+
+  static size_t ArraySize(size_t element_size, uint32_t num_elements);
+};
+
+}  // namespace art
+
+#endif  // ART_RUNTIME_UTILS_DEX_CACHE_ARRAYS_LAYOUT_H_