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      1 /*
      2  * Copyright (C) 2010 Google 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  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
     14  *     its contributors may be used to endorse or promote products derived
     15  *     from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
     18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #ifndef AudioArray_h
     30 #define AudioArray_h
     31 
     32 #include <string.h>
     33 #include "wtf/FastMalloc.h"
     34 #include "wtf/Vector.h"
     35 
     36 namespace WebCore {
     37 
     38 template<typename T>
     39 class AudioArray {
     40 public:
     41     AudioArray() : m_allocation(0), m_alignedData(0), m_size(0) { }
     42     explicit AudioArray(size_t n) : m_allocation(0), m_alignedData(0), m_size(0)
     43     {
     44         allocate(n);
     45     }
     46 
     47     ~AudioArray()
     48     {
     49         fastFree(m_allocation);
     50     }
     51 
     52     // It's OK to call allocate() multiple times, but data will *not* be copied from an initial allocation
     53     // if re-allocated. Allocations are zero-initialized.
     54     void allocate(size_t n)
     55     {
     56         // Although n is a size_t, its true limit is max unsigned because we use unsigned in zeroRange()
     57         // and copyToRange(). Also check for integer overflow.
     58         if (n > std::numeric_limits<unsigned>::max() / sizeof(T))
     59             CRASH();
     60 
     61         unsigned initialSize = sizeof(T) * n;
     62 
     63 #if USE(WEBAUDIO_FFMPEG) || USE(WEBAUDIO_OPENMAX_DL_FFT)
     64         const size_t alignment = 32;
     65 #else
     66         const size_t alignment = 16;
     67 #endif
     68 
     69         if (m_allocation)
     70             fastFree(m_allocation);
     71 
     72         bool isAllocationGood = false;
     73 
     74         while (!isAllocationGood) {
     75             // Initially we try to allocate the exact size, but if it's not aligned
     76             // then we'll have to reallocate and from then on allocate extra.
     77             static size_t extraAllocationBytes = 0;
     78 
     79             // Again, check for integer overflow.
     80             if (initialSize + extraAllocationBytes < initialSize)
     81                 CRASH();
     82 
     83             T* allocation = static_cast<T*>(fastMalloc(initialSize + extraAllocationBytes));
     84             if (!allocation)
     85                 CRASH();
     86             T* alignedData = alignedAddress(allocation, alignment);
     87 
     88             if (alignedData == allocation || extraAllocationBytes == alignment) {
     89                 m_allocation = allocation;
     90                 m_alignedData = alignedData;
     91                 m_size = n;
     92                 isAllocationGood = true;
     93                 zero();
     94             } else {
     95                 extraAllocationBytes = alignment; // always allocate extra after the first alignment failure.
     96                 fastFree(allocation);
     97             }
     98         }
     99     }
    100 
    101     T* data() { return m_alignedData; }
    102     const T* data() const { return m_alignedData; }
    103     size_t size() const { return m_size; }
    104 
    105     T& at(size_t i)
    106     {
    107         // Note that although it is a size_t, m_size is now guaranteed to be
    108         // no greater than max unsigned. This guarantee is enforced in allocate().
    109         ASSERT_WITH_SECURITY_IMPLICATION(i < size());
    110         return data()[i];
    111     }
    112 
    113     T& operator[](size_t i) { return at(i); }
    114 
    115     void zero()
    116     {
    117         // This multiplication is made safe by the check in allocate().
    118         memset(this->data(), 0, sizeof(T) * this->size());
    119     }
    120 
    121     void zeroRange(unsigned start, unsigned end)
    122     {
    123         bool isSafe = (start <= end) && (end <= this->size());
    124         ASSERT(isSafe);
    125         if (!isSafe)
    126             return;
    127 
    128         // This expression cannot overflow because end - start cannot be
    129         // greater than m_size, which is safe due to the check in allocate().
    130         memset(this->data() + start, 0, sizeof(T) * (end - start));
    131     }
    132 
    133     void copyToRange(const T* sourceData, unsigned start, unsigned end)
    134     {
    135         bool isSafe = (start <= end) && (end <= this->size());
    136         ASSERT(isSafe);
    137         if (!isSafe)
    138             return;
    139 
    140         // This expression cannot overflow because end - start cannot be
    141         // greater than m_size, which is safe due to the check in allocate().
    142         memcpy(this->data() + start, sourceData, sizeof(T) * (end - start));
    143     }
    144 
    145 private:
    146     static T* alignedAddress(T* address, intptr_t alignment)
    147     {
    148         intptr_t value = reinterpret_cast<intptr_t>(address);
    149         return reinterpret_cast<T*>((value + alignment - 1) & ~(alignment - 1));
    150     }
    151 
    152     T* m_allocation;
    153     T* m_alignedData;
    154     size_t m_size;
    155 };
    156 
    157 typedef AudioArray<float> AudioFloatArray;
    158 typedef AudioArray<double> AudioDoubleArray;
    159 
    160 } // WebCore
    161 
    162 #endif // AudioArray_h
    163