aligned.h
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00034 
00035 #ifndef ALLOCATORS_ALIGNED_H
00036 #define ALLOCATORS_ALIGNED_H
00037 
00038 #include <cstdlib>
00039 #include <boost/cstdint.hpp>
00040 
00041 namespace allocators
00042 {
00043 
00044 // alignedMalloc/alignedFree implementations found at
00045 // http://www.gamasutra.com/view/feature/3942/data_alignment_part_1.php?page=2
00046 
00053 inline void* alignedMalloc(size_t size, size_t alignment)
00054 {
00055   const int pointerSize = sizeof(void*);
00056   const int requestedSize = size + alignment - 1 + pointerSize;
00057   void* raw = std::malloc(requestedSize);
00058 
00059   if (!raw)
00060   {
00061     return 0;
00062   }
00063 
00064   void* start = (uint8_t*)raw + pointerSize;
00065   void* aligned = (void*)(((uintptr_t)((uint8_t*)start+alignment-1)) & ~(alignment-1));
00066   *(void**)((uint8_t*)aligned-pointerSize) = raw;
00067   return aligned;
00068 }
00069 
00074 inline void alignedFree(void* aligned)
00075 {
00076   if (!aligned)
00077   {
00078     return;
00079   }
00080 
00081   void* raw = *(void**)((uint8_t*)aligned - sizeof(void*));
00082   std::free(raw);
00083 }
00084 
00085 template<class T, size_t align> class AlignedAllocator;
00086 
00087 // specialize for void:
00088 template<size_t align>
00089 class AlignedAllocator<void, align>
00090 {
00091 public:
00092   typedef void* pointer;
00093   typedef const void* const_pointer;
00094   // reference to void members are impossible.
00095   typedef void value_type;
00096 
00097   template<class U>
00098   struct rebind
00099   {
00100     typedef AlignedAllocator<U, align> other;
00101   };
00102 };
00103 
00109 template<class T, size_t align>
00110 class AlignedAllocator
00111 {
00112 public:
00113   typedef size_t size_type;
00114   typedef ptrdiff_t difference_type;
00115   typedef T* pointer;
00116   typedef const T* const_pointer;
00117   typedef T& reference;
00118   typedef const T& const_reference;
00119   typedef T value_type;
00120 
00121   template<class U>
00122   struct rebind
00123   {
00124     typedef AlignedAllocator<U, align> other;
00125   };
00126 
00127   AlignedAllocator() throw ()
00128   {
00129   }
00130 
00131   ~AlignedAllocator() throw ()
00132   {
00133   }
00134 
00135   pointer address(reference r) const
00136   {
00137     return &r;
00138   }
00139   const_pointer address(const_reference r) const
00140   {
00141     return &r;
00142   }
00143   size_type max_size() const throw ()
00144   {
00145     return ~size_type(0);
00146   }
00147   pointer allocate(size_type n, typename AlignedAllocator<void, align>::const_pointer hint = 0)
00148   {
00149     void* mem = alignedMalloc(n * sizeof(T), align);
00150     if (!mem)
00151     {
00152       throw std::bad_alloc();
00153     }
00154 
00155     return static_cast<pointer>(mem);
00156   }
00157   void deallocate(pointer p, size_type n)
00158   {
00159     alignedFree(p);
00160   }
00161 
00162   void construct(pointer p, const_reference val)
00163   {
00164     new (p) T(val);
00165   }
00166   void destroy(pointer p)
00167   {
00168     p->~T();
00169   }
00170 };
00171 
00172 } // namespace allocators
00173 
00174 #endif // ALLOCATORS_ALIGNED_H
00175 


allocators
Author(s): Josh Faust
autogenerated on Wed Aug 26 2015 15:59:56