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// This file is under the public domain.
#pragma once
#include <cstddef>
#include <new>
#include <type_traits>
namespace Common {
template <typename T>
requires std::is_unsigned_v<T>
[[nodiscard]] constexpr T AlignUp(T value, size_t size) {
auto mod{static_cast<T>(value % size)};
value -= mod;
return static_cast<T>(mod == T{0} ? value : value + size);
}
template <typename T>
requires std::is_unsigned_v<T>
[[nodiscard]] constexpr T AlignUpLog2(T value, size_t align_log2) {
return static_cast<T>((value + ((1ULL << align_log2) - 1)) >> align_log2 << align_log2);
}
template <typename T>
requires std::is_unsigned_v<T>
[[nodiscard]] constexpr T AlignDown(T value, size_t size) {
return static_cast<T>(value - value % size);
}
template <typename T>
requires std::is_unsigned_v<T>
[[nodiscard]] constexpr bool Is4KBAligned(T value) {
return (value & 0xFFF) == 0;
}
template <typename T>
requires std::is_unsigned_v<T>
[[nodiscard]] constexpr bool IsWordAligned(T value) {
return (value & 0b11) == 0;
}
template <typename T>
requires std::is_integral_v<T>
[[nodiscard]] constexpr bool IsAligned(T value, size_t alignment) {
using U = typename std::make_unsigned_t<T>;
const U mask = static_cast<U>(alignment - 1);
return (value & mask) == 0;
}
template <typename T, typename U>
requires std::is_integral_v<T>
[[nodiscard]] constexpr T DivideUp(T x, U y) {
return (x + (y - 1)) / y;
}
template <typename T, size_t Align = 16>
class AlignmentAllocator {
public:
using value_type = T;
using size_type = size_t;
using difference_type = ptrdiff_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::false_type;
constexpr AlignmentAllocator() noexcept = default;
template <typename T2>
constexpr AlignmentAllocator(const AlignmentAllocator<T2, Align>&) noexcept {}
[[nodiscard]] T* allocate(size_type n) {
return static_cast<T*>(::operator new (n * sizeof(T), std::align_val_t{Align}));
}
void deallocate(T* p, size_type n) {
::operator delete (p, n * sizeof(T), std::align_val_t{Align});
}
template <typename T2>
struct rebind {
using other = AlignmentAllocator<T2, Align>;
};
template <typename T2, size_t Align2>
constexpr bool operator==(const AlignmentAllocator<T2, Align2>&) const noexcept {
return std::is_same_v<T, T2> && Align == Align2;
}
};
} // namespace Common
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