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#ifndef AL_MALLOC_H
#define AL_MALLOC_H
#include <stddef.h>
#include <memory>
#include <limits>
#include <algorithm>
void *al_malloc(size_t alignment, size_t size);
void *al_calloc(size_t alignment, size_t size);
void al_free(void *ptr) noexcept;
size_t al_get_page_size(void) noexcept;
/**
* Returns non-0 if the allocation function has direct alignment handling.
* Otherwise, the standard malloc is used with an over-allocation and pointer
* offset strategy.
*/
int al_is_sane_alignment_allocator(void) noexcept;
#define DEF_NEWDEL(T) \
void *operator new(size_t size) \
{ \
void *ret = al_malloc(alignof(T), size); \
if(!ret) throw std::bad_alloc(); \
return ret; \
} \
void operator delete(void *block) noexcept { al_free(block); }
#define DEF_PLACE_NEWDEL() \
void *operator new(size_t /*size*/, void *ptr) noexcept { return ptr; } \
void operator delete(void *block) noexcept { al_free(block); } \
void operator delete(void* /*block*/, void* /*ptr*/) noexcept { }
namespace al {
#define REQUIRES(...) typename std::enable_if<(__VA_ARGS__),int>::type = 0
template<typename T, size_t alignment=alignof(T)>
struct allocator : public std::allocator<T> {
using size_type = size_t;
using pointer = T*;
using const_pointer = const T*;
template<typename U>
struct rebind {
using other = allocator<U, alignment>;
};
pointer allocate(size_type n, const void* = nullptr)
{
if(n > std::numeric_limits<size_t>::max() / sizeof(T))
throw std::bad_alloc();
void *ret{al_malloc(alignment, n*sizeof(T))};
if(!ret) throw std::bad_alloc();
return static_cast<pointer>(ret);
}
void deallocate(pointer p, size_type)
{ al_free(p); }
allocator() : std::allocator<T>() { }
allocator(const allocator &a) : std::allocator<T>(a) { }
template<class U>
allocator(const allocator<U,alignment> &a) : std::allocator<T>(a)
{ }
};
template<size_t alignment, typename T>
inline T* assume_aligned(T *ptr) noexcept
{
static_assert((alignment & (alignment-1)) == 0, "alignment must be a power of 2");
#ifdef __GNUC__
return static_cast<T*>(__builtin_assume_aligned(ptr, alignment));
#elif defined(_MSC_VER)
auto ptrval = reinterpret_cast<uintptr_t>(ptr);
if((ptrval&(alignment-1)) != 0) __assume(0);
return reinterpret_cast<T*>(ptrval);
#else
return ptr;
#endif
}
template<typename T>
inline void destroy_at(T *ptr) { ptr->~T(); }
template<typename T>
inline void destroy(T first, const T end)
{
while(first != end)
{
destroy_at(std::addressof(*first));
++first;
}
}
template<typename T, typename N, REQUIRES(std::is_integral<N>::value)>
inline T destroy_n(T first, N count)
{
if(count != 0)
{
do {
destroy_at(std::addressof(*first));
++first;
} while(--count);
}
return first;
}
template<typename T>
inline void uninitialized_default_construct(T first, const T last)
{
using ValueT = typename std::iterator_traits<T>::value_type;
T current{first};
try {
while(current != last)
{
::new (static_cast<void*>(std::addressof(*current))) ValueT;
++current;
}
}
catch(...) {
destroy(first, current);
throw;
}
}
template<typename T, typename N, REQUIRES(std::is_integral<N>::value)>
inline T uninitialized_default_construct_n(T first, N count)
{
using ValueT = typename std::iterator_traits<T>::value_type;
T current{first};
if(count != 0)
{
try {
do {
::new (static_cast<void*>(std::addressof(*current))) ValueT;
++current;
} while(--count);
}
catch(...) {
destroy(first, current);
throw;
}
}
return current;
}
/* std::make_unique was added with C++14, so until we rely on that, make our
* own version.
*/
template<typename T, typename ...ArgsT>
std::unique_ptr<T> make_unique(ArgsT&&...args)
{ return std::unique_ptr<T>{new T{std::forward<ArgsT>(args)...}}; }
/* A flexible array type. Used either standalone or at the end of a parent
* struct, with placement new, to have a run-time-sized array that's embedded
* with its size.
*/
template<typename T, size_t alignment=alignof(T)>
struct FlexArray {
const size_t mSize;
alignas(alignment) T mArray[];
static constexpr size_t Sizeof(size_t count, size_t base=0u) noexcept
{
return base +
std::max<size_t>(offsetof(FlexArray, mArray) + sizeof(T)*count, sizeof(FlexArray));
}
FlexArray(size_t size) : mSize{size}
{ uninitialized_default_construct_n(mArray, mSize); }
~FlexArray()
{ destroy_n(mArray, mSize); }
FlexArray(const FlexArray&) = delete;
FlexArray& operator=(const FlexArray&) = delete;
size_t size() const noexcept { return mSize; }
T *data() noexcept { return mArray; }
const T *data() const noexcept { return mArray; }
T& operator[](size_t i) noexcept { return mArray[i]; }
const T& operator[](size_t i) const noexcept { return mArray[i]; }
T& front() noexcept { return mArray[0]; }
const T& front() const noexcept { return mArray[0]; }
T& back() noexcept { return mArray[mSize-1]; }
const T& back() const noexcept { return mArray[mSize-1]; }
T *begin() noexcept { return mArray; }
const T *begin() const noexcept { return mArray; }
const T *cbegin() const noexcept { return mArray; }
T *end() noexcept { return mArray + mSize; }
const T *end() const noexcept { return mArray + mSize; }
const T *cend() const noexcept { return mArray + mSize; }
DEF_PLACE_NEWDEL()
};
#undef REQUIRES
} // namespace al
#endif /* AL_MALLOC_H */
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