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/* Copyright (C) 2010 Wildfire Games.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* STL allocator for aligned memory
*/
#ifndef ALIGNED_ALLOCATOR
#define ALIGNED_ALLOCATOR
#include "lib/bits.h" // round_up
#include "lib/sysdep/arch/x86_x64/cache.h"
#include "lib/sysdep/rtl.h" // rtl_AllocateAligned
/**
* stateless STL allocator that aligns elements to the L1 cache line size.
*
* note: the alignment is hard-coded to avoid any allocator state.
* this avoids portability problems, which is important since allocators
* are rather poorly specified.
*
* references:
* http://www.tantalon.com/pete/customallocators.ppt
* http://www.flipcode.com/archives/Aligned_Block_Allocation.shtml
* http://www.josuttis.com/cppcode/allocator.html
*
* derived from code that bears the following copyright notice:
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
**/
template<class T>
class AlignedAllocator
{
public:
// type definitions
typedef T value_type;
typedef T* pointer;
typedef const T* const_pointer;
typedef T& reference;
typedef const T& const_reference;
typedef std::size_t size_type;
typedef std::ptrdiff_t difference_type;
// rebind allocator to type U
template <class U>
struct rebind
{
typedef AlignedAllocator<U> other;
};
pointer address(reference value) const
{
return &value;
}
const_pointer address(const_reference value) const
{
return &value;
}
NOTHROW_DEFINE AlignedAllocator()
{
}
NOTHROW_DEFINE AlignedAllocator(const AlignedAllocator&)
{
}
template <class U>
NOTHROW_DEFINE AlignedAllocator (const AlignedAllocator<U>&)
{
}
NOTHROW_DEFINE ~AlignedAllocator()
{
}
NOTHROW_DEFINE size_type max_size() const
{
// maximum number of *elements* that can be allocated
return std::numeric_limits<std::size_t>::max() / sizeof(T);
}
// allocate uninitialized storage
pointer allocate(size_type numElements)
{
const size_type alignment = x86_x64::Caches(x86_x64::L1D)->entrySize;
const size_type elementSize = round_up(sizeof(T), alignment);
const size_type size = numElements * elementSize;
pointer p = (pointer)rtl_AllocateAligned(size, alignment);
return p;
}
// deallocate storage of elements that have been destroyed
void deallocate(pointer p, size_type UNUSED(num))
{
rtl_FreeAligned((void*)p);
}
void construct(pointer p, const T& value)
{
new((void*)p) T(value);
}
void destroy(pointer p)
{
p->~T();
UNUSED2(p); // otherwise, warning is raised for reasons unknown
}
};
// indicate that all specializations of this allocator are interchangeable
template <class T1, class T2>
NOTHROW_DEFINE bool operator==(const AlignedAllocator<T1>&, const AlignedAllocator<T2>&)
{
return true;
}
template <class T1, class T2>
NOTHROW_DEFINE bool operator!=(const AlignedAllocator<T1>&, const AlignedAllocator<T2>&)
{
return false;
}
#endif // #ifndef ALIGNED_ALLOCATOR
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