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// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QENDIAN_P_H
#define QENDIAN_P_H
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
#include <QtCore/qendian.h>
#include <QtCore/private/qglobal_p.h>
QT_BEGIN_NAMESPACE
enum class QSpecialIntegerBitfieldInitializer {};
constexpr QSpecialIntegerBitfieldInitializer QSpecialIntegerBitfieldZero{};
template<class S>
class QSpecialIntegerStorage
{
public:
using UnsignedStorageType = std::make_unsigned_t<typename S::StorageType>;
constexpr QSpecialIntegerStorage() = default;
constexpr QSpecialIntegerStorage(QSpecialIntegerBitfieldInitializer) : val(0) {}
constexpr QSpecialIntegerStorage(UnsignedStorageType initial) : val(initial) {}
UnsignedStorageType val;
};
template<class S, int pos, int width, class T = typename S::StorageType>
class QSpecialIntegerAccessor;
template<class S, int pos, int width, class T = typename S::StorageType>
class QSpecialIntegerConstAccessor
{
Q_DISABLE_COPY_MOVE(QSpecialIntegerConstAccessor)
public:
using Storage = const QSpecialIntegerStorage<S>;
using Type = T;
using UnsignedType = std::make_unsigned_t<T>;
operator Type() const noexcept
{
if constexpr (std::is_signed_v<Type>) {
UnsignedType i = S::fromSpecial(storage->val);
i <<= (sizeof(Type) * 8) - width - pos;
Type t = Type(i);
t >>= (sizeof(Type) * 8) - width;
return t;
}
return (S::fromSpecial(storage->val) & mask()) >> pos;
}
bool operator!() const noexcept { return !(storage->val & S::toSpecial(mask())); }
static constexpr UnsignedType mask() noexcept
{
if constexpr (width == sizeof(UnsignedType) * 8) {
static_assert(pos == 0);
return ~UnsignedType(0);
} else {
return ((UnsignedType(1) << width) - 1) << pos;
}
}
private:
template<class Storage, typename... Accessors>
friend class QSpecialIntegerBitfieldUnion;
friend class QSpecialIntegerAccessor<S, pos, width, T>;
explicit QSpecialIntegerConstAccessor(Storage *storage) : storage(storage) {}
friend bool operator==(const QSpecialIntegerConstAccessor<S, pos, width, T> &i,
const QSpecialIntegerConstAccessor<S, pos, width, T> &j) noexcept
{
return ((i.storage->val ^ j.storage->val) & S::toSpecial(mask())) == 0;
}
friend bool operator!=(const QSpecialIntegerConstAccessor<S, pos, width, T> &i,
const QSpecialIntegerConstAccessor<S, pos, width, T> &j) noexcept
{
return ((i.storage->val ^ j.storage->val) & S::toSpecial(mask())) != 0;
}
Storage *storage;
};
template<class S, int pos, int width, class T>
class QSpecialIntegerAccessor
{
Q_DISABLE_COPY_MOVE(QSpecialIntegerAccessor)
public:
using Const = QSpecialIntegerConstAccessor<S, pos, width, T>;
using Storage = QSpecialIntegerStorage<S>;
using Type = T;
using UnsignedType = std::make_unsigned_t<T>;
QSpecialIntegerAccessor &operator=(Type t)
{
UnsignedType i = S::fromSpecial(storage->val);
i &= ~Const::mask();
i |= (UnsignedType(t) << pos) & Const::mask();
storage->val = S::toSpecial(i);
return *this;
}
operator Const() { return Const(storage); }
private:
template<class Storage, typename... Accessors>
friend class QSpecialIntegerBitfieldUnion;
explicit QSpecialIntegerAccessor(Storage *storage) : storage(storage) {}
Storage *storage;
};
template<class S, typename... Accessors>
class QSpecialIntegerBitfieldUnion
{
public:
constexpr QSpecialIntegerBitfieldUnion() = default;
constexpr QSpecialIntegerBitfieldUnion(QSpecialIntegerBitfieldInitializer initial)
: storage(initial)
{}
constexpr QSpecialIntegerBitfieldUnion(
typename QSpecialIntegerStorage<S>::UnsignedStorageType initial)
: storage(initial)
{}
template<typename A>
void set(typename A::Type value)
{
member<A>() = value;
}
template<typename A>
typename A::Type get() const
{
return member<A>();
}
typename QSpecialIntegerStorage<S>::UnsignedStorageType data() const
{
return storage.val;
}
private:
template<typename A>
static constexpr bool isAccessor = std::disjunction_v<std::is_same<A, Accessors>...>;
template<typename A>
A member()
{
static_assert(isAccessor<A>);
return A(&storage);
}
template<typename A>
typename A::Const member() const
{
static_assert(isAccessor<A>);
return typename A::Const(&storage);
}
QSpecialIntegerStorage<S> storage;
};
template<typename T, typename... Accessors>
using QLEIntegerBitfieldUnion
= QSpecialIntegerBitfieldUnion<QLittleEndianStorageType<T>, Accessors...>;
template<typename T, typename... Accessors>
using QBEIntegerBitfieldUnion
= QSpecialIntegerBitfieldUnion<QBigEndianStorageType<T>, Accessors...>;
template<typename... Accessors>
using qint32_le_bitfield_union = QLEIntegerBitfieldUnion<int, Accessors...>;
template<typename... Accessors>
using quint32_le_bitfield_union = QLEIntegerBitfieldUnion<uint, Accessors...>;
template<typename... Accessors>
using qint32_be_bitfield_union = QBEIntegerBitfieldUnion<int, Accessors...>;
template<typename... Accessors>
using quint32_be_bitfield_union = QBEIntegerBitfieldUnion<uint, Accessors...>;
template<int pos, int width, typename T = int>
using qint32_le_bitfield_member
= QSpecialIntegerAccessor<QLittleEndianStorageType<int>, pos, width, T>;
template<int pos, int width, typename T = uint>
using quint32_le_bitfield_member
= QSpecialIntegerAccessor<QLittleEndianStorageType<uint>, pos, width, T>;
template<int pos, int width, typename T = int>
using qint32_be_bitfield_member
= QSpecialIntegerAccessor<QBigEndianStorageType<int>, pos, width, T>;
template<int pos, int width, typename T = uint>
using quint32_be_bitfield_member
= QSpecialIntegerAccessor<QBigEndianStorageType<uint>, pos, width, T>;
QT_END_NAMESPACE
#endif // QENDIAN_P_H
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