asteroidgen/src/AlignedAllocator.h

#pragma once

#include <malloc.h>
#include <assert.h>

#include <type_traits>
#include <memory>

enum class Alignment
	: size_t
	{
		Normal = sizeof(void*), SSE = 16, AVX = 32,
};

namespace detail {
void* allocate_aligned_memory(size_t align, size_t size);
void deallocate_aligned_memory(void* ptr) noexcept;
}

template<typename T, Alignment Align = Alignment::SSE>
class AlignedAllocator;

template<Alignment Align>
class AlignedAllocator<void, Align> {
public:
	typedef void* pointer;
	typedef const void* const_pointer;
	typedef void value_type;

	template<class U> struct rebind {
		typedef AlignedAllocator<U, Align> other;
	};
};

template<typename T, Alignment Align>
class AlignedAllocator {
public:
	typedef T value_type;
	typedef T* pointer;
	typedef const T* const_pointer;
	typedef T& reference;
	typedef const T& const_reference;
	typedef size_t size_type;
	typedef ptrdiff_t difference_type;

	typedef std::true_type propagate_on_container_move_assignment;

	template<class U>
	struct rebind {
		typedef AlignedAllocator<U, Align> other;
	};

public:
	AlignedAllocator() noexcept
	{
	}

	template<class U>
	AlignedAllocator(const AlignedAllocator<U, Align>&) noexcept
	{
	}

	size_type max_size() const noexcept
	{
		return (size_type(~0) - size_type(Align)) / sizeof(T);
	}

	pointer address(reference x) const noexcept
	{
		return std::addressof(x);
	}

	const_pointer address(const_reference x) const noexcept
	{
		return std::addressof(x);
	}

	pointer allocate(size_type n,
			typename AlignedAllocator<void, Align>::const_pointer = 0) {
		const size_type alignment = static_cast<size_type>(Align);
		void* ptr = detail::allocate_aligned_memory(alignment, n * sizeof(T));
		if (ptr == nullptr) {
			throw std::bad_alloc();
		}

		return reinterpret_cast<pointer>(ptr);
	}

	void deallocate(pointer p, size_type) noexcept
	{
		detail::deallocate_aligned_memory(p);
	}

	template<class U, class ...Args>
	void construct(U* p, Args&&... args) {
		::new (reinterpret_cast<void*>(p)) U(std::forward<Args>(args)...);
	}

	void destroy(pointer p) {
		p->~T();
	}
};

template<typename T, Alignment Align>
class AlignedAllocator<const T, Align> {
public:
	typedef T value_type;
	typedef const T* pointer;
	typedef const T* const_pointer;
	typedef const T& reference;
	typedef const T& const_reference;
	typedef size_t size_type;
	typedef ptrdiff_t difference_type;

	typedef std::true_type propagate_on_container_move_assignment;

	template<class U>
	struct rebind {
		typedef AlignedAllocator<U, Align> other;
	};

public:
	AlignedAllocator() noexcept
	{
	}

	template<class U>
	AlignedAllocator(const AlignedAllocator<U, Align>&) noexcept
	{
	}

	size_type max_size() const noexcept
	{
		return (size_type(~0) - size_type(Align)) / sizeof(T);
	}

	const_pointer address(const_reference x) const noexcept
	{
		return std::addressof(x);
	}

	pointer allocate(size_type n,
			typename AlignedAllocator<void, Align>::const_pointer = 0) {
		const size_type alignment = static_cast<size_type>(Align);
		void* ptr = detail::allocate_aligned_memory(alignment, n * sizeof(T));
		if (ptr == nullptr) {
			throw std::bad_alloc();
		}

		return reinterpret_cast<pointer>(ptr);
	}

	void deallocate(pointer p, size_type) noexcept
	{
		detail::deallocate_aligned_memory(p);
	}

	template<class U, class ...Args>
	void construct(U* p, Args&&... args) {
		::new (reinterpret_cast<void*>(p)) U(std::forward<Args>(args)...);
	}

	void destroy(pointer p) {
		p->~T();
	}
};

template<typename T, Alignment TAlign, typename U, Alignment UAlign>
inline
bool operator==(const AlignedAllocator<T, TAlign>&,
		const AlignedAllocator<U, UAlign>&) noexcept
		{
	return TAlign == UAlign;
}

template<typename T, Alignment TAlign, typename U, Alignment UAlign>
inline
bool operator!=(const AlignedAllocator<T, TAlign>&,
		const AlignedAllocator<U, UAlign>&) noexcept
		{
	return TAlign != UAlign;
}

inline void*
detail::allocate_aligned_memory(size_t align, size_t size) {
	assert(align >= sizeof(void*));
	//assert(nail::is_power_of_two(align));

	if (size == 0) {
		return nullptr;
	}

	void* ptr = nullptr;
	int rc = posix_memalign(&ptr, align, size);

	if (rc != 0) {
		return nullptr;
	}

	return ptr;
}

inline void detail::deallocate_aligned_memory(void *ptr) noexcept
{
	free(ptr);
}