third_party/WebKit/Source/wtf/typed_arrays/ArrayBufferView.h

/*
 * Copyright (C) 2009 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef ArrayBufferView_h
#define ArrayBufferView_h

#include "wtf/PassRefPtr.h"
#include "wtf/RefCounted.h"
#include "wtf/RefPtr.h"
#include "wtf/WTFExport.h"
#include "wtf/typed_arrays/ArrayBuffer.h"
#include <limits.h>

namespace WTF {

class WTF_EXPORT ArrayBufferView : public RefCounted<ArrayBufferView> {
 public:
  enum ViewType {
    TypeInt8,
    TypeUint8,
    TypeUint8Clamped,
    TypeInt16,
    TypeUint16,
    TypeInt32,
    TypeUint32,
    TypeFloat32,
    TypeFloat64,
    TypeDataView
  };
  virtual ViewType type() const = 0;
  const char* typeName();

  ArrayBuffer* buffer() const { return m_buffer.get(); }

  void* baseAddress() const {
    DCHECK(!isShared());
    return m_baseAddress;
  }

  unsigned byteOffset() const { return m_byteOffset; }

  virtual unsigned byteLength() const = 0;
  virtual unsigned typeSize() const = 0;

  void setNeuterable(bool flag) { m_isNeuterable = flag; }
  bool isNeuterable() const { return m_isNeuterable; }
  bool isShared() const { return m_buffer ? m_buffer->isShared() : false; }

  virtual ~ArrayBufferView();

 protected:
  ArrayBufferView(PassRefPtr<ArrayBuffer>, unsigned byteOffset);

  inline bool setImpl(ArrayBufferView*, unsigned byteOffset);

  // Helper to verify that a given sub-range of an ArrayBuffer is
  // within range.
  template <typename T>
  static bool verifySubRange(PassRefPtr<ArrayBuffer> buffer,
                             unsigned byteOffset,
                             unsigned numElements) {
    if (!buffer)
      return false;
    if (sizeof(T) > 1 && byteOffset % sizeof(T))
      return false;
    if (byteOffset > buffer->byteLength())
      return false;
    unsigned remainingElements =
        (buffer->byteLength() - byteOffset) / sizeof(T);
    if (numElements > remainingElements)
      return false;
    return true;
  }

  virtual void neuter();

  // This is the address of the ArrayBuffer's storage, plus the byte offset.
  void* m_baseAddress;

  unsigned m_byteOffset : 31;
  unsigned m_isNeuterable : 1;

 private:
  friend class ArrayBuffer;
  RefPtr<ArrayBuffer> m_buffer;
  ArrayBufferView* m_prevView;
  ArrayBufferView* m_nextView;
};

bool ArrayBufferView::setImpl(ArrayBufferView* array, unsigned byteOffset) {
  if (byteOffset > byteLength() ||
      byteOffset + array->byteLength() > byteLength() ||
      byteOffset + array->byteLength() < byteOffset) {
    // Out of range offset or overflow
    return false;
  }

  char* base = static_cast<char*>(baseAddress());
  memmove(base + byteOffset, array->baseAddress(), array->byteLength());
  return true;
}

}  // namespace WTF

using WTF::ArrayBufferView;

#endif  // ArrayBufferView_h