1  /*
 2   * Copyright (C) 2013-2017 Apple Inc. All rights reserved.
 3   *
 4   * Redistribution and use in source and binary forms, with or without
 5   * modification, are permitted provided that the following conditions
 6   * are met:
 7   *
 8   * 1.  Redistributions of source code must retain the above copyright
 9   *     notice, this list of conditions and the following disclaimer.
10   * 2.  Redistributions in binary form must reproduce the above copyright
11   *     notice, this list of conditions and the following disclaimer in the
12   *     documentation and/or other materials provided with the distribution.
13   *
14   * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
15   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
16   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
17   * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
18   * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
19   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
20   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
21   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24   */
25  
26  #pragma once
27  
28  #include "ArrayBufferView.h"
29  #include <wtf/FlipBytes.h>
30  
31  namespace JSC {
32  
33  class DataView final : public ArrayBufferView {
34  public:
35      JS_EXPORT_PRIVATE static Ref<DataView> create(RefPtr<ArrayBuffer>&&, unsigned byteOffset, unsigned length);
36      static Ref<DataView> create(RefPtr<ArrayBuffer>&&);
37      
38      TypedArrayType getType() const final
39      {
40          return TypeDataView;
41      }
42  
43      JSArrayBufferView* wrap(JSGlobalObject*, JSGlobalObject*) final;
44      
45      template<typename T>
46      T get(unsigned offset, bool littleEndian, bool* status = nullptr)
47      {
48          if (status) {
49              if (offset + sizeof(T) > byteLength()) {
50                  *status = false;
51                  return T();
52              }
53              *status = true;
54          } else
55              RELEASE_ASSERT(offset + sizeof(T) <= byteLength());
56          return flipBytesIfLittleEndian(
57              *reinterpret_cast<T*>(static_cast<uint8_t*>(m_baseAddress.get(byteLength())) + offset),
58              littleEndian);
59      }
60      
61      template<typename T>
62      T read(unsigned& offset, bool littleEndian, bool* status = nullptr)
63      {
64          T result = this->template get<T>(offset, littleEndian, status);
65          if (!status || *status)
66              offset += sizeof(T);
67          return result;
68      }
69      
70      template<typename T>
71      void set(unsigned offset, T value, bool littleEndian, bool* status = nullptr)
72      {
73          if (status) {
74              if (offset + sizeof(T) > byteLength()) {
75                  *status = false;
76                  return;
77              }
78              *status = true;
79          } else
80              RELEASE_ASSERT(offset + sizeof(T) <= byteLength());
81          *reinterpret_cast<T*>(static_cast<uint8_t*>(m_baseAddress.get(byteLength())) + offset) =
82              flipBytesIfLittleEndian(value, littleEndian);
83      }
84  
85  private:
86      DataView(RefPtr<ArrayBuffer>&&, unsigned byteOffset, unsigned byteLength);
87  };
88  
89  } // namespace JSC