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Atmosphere/libraries/libvapours/include/vapours/util/util_bitpack.hpp
2020-04-21 20:23:50 -07:00

96 lines
4.2 KiB
C++

/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <vapours/common.hpp>
#include <vapours/assert.hpp>
namespace ams::util {
namespace impl {
template<typename IntegralStorageType>
struct BitPack {
IntegralStorageType value;
private:
static_assert(std::is_integral<IntegralStorageType>::value);
static_assert(std::is_unsigned<IntegralStorageType>::value);
template<size_t Index, size_t Count>
static constexpr inline IntegralStorageType Mask = [] {
static_assert(Index < BITSIZEOF(IntegralStorageType));
static_assert(0 < Count && Count <= BITSIZEOF(IntegralStorageType));
static_assert(Index + Count <= BITSIZEOF(IntegralStorageType));
if constexpr (Count == BITSIZEOF(IntegralStorageType)) {
return ~IntegralStorageType(0);
} else {
return ((IntegralStorageType(1) << Count) - 1) << Index;
}
}();
public:
template<size_t _Index, size_t _Count, typename T>
struct Field {
using Type = T;
static constexpr size_t Index = _Index;
static constexpr size_t Count = _Count;
static constexpr size_t Next = Index + Count;
using BitPackType = BitPack<IntegralStorageType>;
static_assert(std::is_pod<BitPackType>::value);
static_assert(Mask<Index, Count> != 0);
static_assert(std::is_integral<T>::value || std::is_enum<T>::value);
static_assert(!std::is_same<T, bool>::value || Count == 1);
};
public:
constexpr ALWAYS_INLINE void Clear() {
constexpr IntegralStorageType Zero = IntegralStorageType(0);
this->value = Zero;
}
template<typename FieldType>
constexpr ALWAYS_INLINE typename FieldType::Type Get() const {
static_assert(std::is_same<FieldType, Field<FieldType::Index, FieldType::Count, typename FieldType::Type>>::value);
return static_cast<typename FieldType::Type>((this->value & Mask<FieldType::Index, FieldType::Count>) >> FieldType::Index);
}
template<typename FieldType>
constexpr ALWAYS_INLINE void Set(typename FieldType::Type field_value) {
static_assert(std::is_same<FieldType, Field<FieldType::Index, FieldType::Count, typename FieldType::Type>>::value);
constexpr IntegralStorageType FieldMask = Mask<FieldType::Index, FieldType::Count>;
this->value &= ~FieldMask;
this->value |= (static_cast<IntegralStorageType>(field_value) << FieldType::Index) & FieldMask;
}
};
}
using BitPack8 = impl::BitPack<u8>;
using BitPack16 = impl::BitPack<u16>;
using BitPack32 = impl::BitPack<u32>;
using BitPack64 = impl::BitPack<u64>;
static_assert(std::is_pod<BitPack8>::value);
static_assert(std::is_pod<BitPack16>::value);
static_assert(std::is_pod<BitPack32>::value);
static_assert(std::is_pod<BitPack64>::value);
static_assert(std::is_trivially_destructible<BitPack8 >::value);
static_assert(std::is_trivially_destructible<BitPack16>::value);
static_assert(std::is_trivially_destructible<BitPack32>::value);
static_assert(std::is_trivially_destructible<BitPack64>::value);
}