1 /*

     2  * Copyright (C) 2009 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  * 1. Redistributions of source code must retain the above copyright

     8  *    notice, this list of conditions and the following disclaimer.

     9  * 2. Redistributions in binary form must reproduce the above copyright

    10  *    notice, this list of conditions and the following disclaimer in the

    11  *    documentation and/or other materials provided with the distribution.

    12  *

    13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY

    14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

    15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

    16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR

    17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

    18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

    19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

    20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

    21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

    22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

    23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 

    24  */

    25 

    26 #ifndef ArrayBufferView_h

    27 #define ArrayBufferView_h

    28 

    29 #include <algorithm>

    30 #include "ExceptionCode.h"

    31 #include <limits.h>

    32 #include <wtf/PassRefPtr.h>

    33 #include <wtf/RefCounted.h>

    34 #include <wtf/RefPtr.h>

    35 #include "ArrayBuffer.h"

    36 

    37 namespace WebCore {

    38 

    39 class ArrayBufferView : public RefCounted<ArrayBufferView> {

    40   public:

    41     virtual bool isByteArray() const { return false; }

    42     virtual bool isUnsignedByteArray() const { return false; }

    43     virtual bool isShortArray() const { return false; }

    44     virtual bool isUnsignedShortArray() const { return false; }

    45     virtual bool isIntArray() const { return false; }

    46     virtual bool isUnsignedIntArray() const { return false; }

    47     virtual bool isFloatArray() const { return false; }

    48 

    49     PassRefPtr<ArrayBuffer> buffer() const

    50     {

    51         return m_buffer;

    52     }

    53 

    54     void* baseAddress() const

    55     {

    56         return m_baseAddress;

    57     }

    58 

    59     unsigned byteOffset() const

    60     {

    61         return m_byteOffset;

    62     }

    63 

    64     virtual unsigned length() const = 0;

    65     virtual unsigned byteLength() const = 0;

    66     virtual PassRefPtr<ArrayBufferView> slice(int start, int end) const = 0;

    67 

    68     virtual ~ArrayBufferView();

    69 

    70   protected:

    71     ArrayBufferView(PassRefPtr<ArrayBuffer> buffer, unsigned byteOffset);

    72 

    73     void setImpl(ArrayBufferView* array, unsigned byteOffset, ExceptionCode& ec);

    74 

    75     static void calculateOffsetAndLength(int start, int end, unsigned arraySize,

    76                                          unsigned* offset, unsigned* length);

    77 

    78     // Helper to verify that a given sub-range of an ArrayBuffer is

    79     // within range.

    80     template <typename T>

    81     static bool verifySubRange(PassRefPtr<ArrayBuffer> buffer,

    82                                unsigned byteOffset,

    83                                unsigned numElements)

    84     {

    85         if (!buffer)

    86             return false;

    87         if (sizeof(T) > 1 && byteOffset % sizeof(T))

    88             return false;

    89         if (byteOffset > buffer->byteLength())

    90             return false;

    91         unsigned remainingElements = (buffer->byteLength() - byteOffset) / sizeof(T);

    92         if (numElements > remainingElements)

    93             return false;

    94         return true;

    95     }

    96 

    97     // Input offset is in number of elements from this array's view;

    98     // output offset is in number of bytes from the underlying buffer's view.

    99     template <typename T>

   100     static void clampOffsetAndNumElements(PassRefPtr<ArrayBuffer> buffer,

   101                                           unsigned arrayByteOffset,

   102                                           unsigned *offset,

   103                                           unsigned *numElements)

   104     {

   105         unsigned maxOffset = (UINT_MAX - arrayByteOffset) / sizeof(T);

   106         if (*offset > maxOffset) {

   107             *offset = buffer->byteLength();

   108             *numElements = 0;

   109             return;

   110         }

   111         *offset = arrayByteOffset + *offset * sizeof(T);

   112         *offset = std::min(buffer->byteLength(), *offset);

   113         unsigned remainingElements = (buffer->byteLength() - *offset) / sizeof(T);

   114         *numElements = std::min(remainingElements, *numElements);

   115     }

   116 

   117     // This is the address of the ArrayBuffer's storage, plus the byte offset.

   118     void* m_baseAddress;

   119 

   120     unsigned m_byteOffset;

   121 

   122   private:

   123     RefPtr<ArrayBuffer> m_buffer;

   124 };

   125 

   126 } // namespace WebCore

   127 

   128 #endif // ArrayBufferView_h