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// This file is under the public domain.
#pragma once
#include <cstddef>
#include <memory>
#include <type_traits>
namespace Common {
template <typename T>
constexpr T AlignUp(T value, std::size_t size) {
static_assert(std::is_unsigned_v<T>, "T must be an unsigned value.");
auto mod{static_cast<T>(value % size)};
value -= mod;
return static_cast<T>(mod == T{0} ? value : value + size);
}
template <typename T>
constexpr T AlignDown(T value, std::size_t size) {
static_assert(std::is_unsigned_v<T>, "T must be an unsigned value.");
return static_cast<T>(value - value % size);
}
template <typename T>
constexpr T AlignBits(T value, std::size_t align) {
static_assert(std::is_unsigned_v<T>, "T must be an unsigned value.");
return static_cast<T>((value + ((1ULL << align) - 1)) >> align << align);
}
template <typename T>
constexpr bool Is4KBAligned(T value) {
static_assert(std::is_unsigned_v<T>, "T must be an unsigned value.");
return (value & 0xFFF) == 0;
}
template <typename T>
constexpr bool IsWordAligned(T value) {
static_assert(std::is_unsigned_v<T>, "T must be an unsigned value.");
return (value & 0b11) == 0;
}
template <typename T>
constexpr bool IsAligned(T value, std::size_t alignment) {
using U = typename std::make_unsigned<T>::type;
const U mask = static_cast<U>(alignment - 1);
return (value & mask) == 0;
}
template <typename T, std::size_t Align = 16>
class AlignmentAllocator {
public:
using value_type = T;
using size_type = std::size_t;
using difference_type = std::ptrdiff_t;
using pointer = T*;
using const_pointer = const T*;
using reference = T&;
using const_reference = const T&;
using propagate_on_container_copy_assignment = std::true_type;
using propagate_on_container_move_assignment = std::true_type;
using propagate_on_container_swap = std::true_type;
using is_always_equal = std::true_type;
public:
constexpr AlignmentAllocator() noexcept = default;
template <typename T2>
constexpr AlignmentAllocator(const AlignmentAllocator<T2, Align>&) noexcept {}
pointer address(reference r) noexcept {
return std::addressof(r);
}
const_pointer address(const_reference r) const noexcept {
return std::addressof(r);
}
pointer allocate(size_type n) {
return static_cast<pointer>(::operator new (n, std::align_val_t{Align}));
}
void deallocate(pointer p, size_type) {
::operator delete (p, std::align_val_t{Align});
}
void construct(pointer p, const value_type& wert) {
new (p) value_type(wert);
}
void destroy(pointer p) {
p->~value_type();
}
size_type max_size() const noexcept {
return size_type(-1) / sizeof(value_type);
}
template <typename T2>
struct rebind {
using other = AlignmentAllocator<T2, Align>;
};
bool operator!=(const AlignmentAllocator<T, Align>& other) const noexcept {
return !(*this == other);
}
// Returns true if and only if storage allocated from *this
// can be deallocated from other, and vice versa.
// Always returns true for stateless allocators.
bool operator==(const AlignmentAllocator<T, Align>& other) const noexcept {
return true;
}
};
} // namespace Common
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