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Atmosphere/libraries/libvapours/include/vapours/util/util_bitset.hpp

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2020-01-31 01:45:54 +00:00
/*
* 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
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#include <vapours/common.hpp>
#include <vapours/assert.hpp>
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namespace ams::util {
namespace impl {
template<typename Storage, size_t N>
class BitSet {
private:
static_assert(std::is_integral<Storage>::value);
static_assert(std::is_unsigned<Storage>::value);
static_assert(sizeof(Storage) <= sizeof(u64));
static constexpr size_t FlagsPerWord = BITSIZEOF(Storage);
static constexpr size_t NumWords = util::AlignUp(N, FlagsPerWord) / FlagsPerWord;
static constexpr ALWAYS_INLINE auto CountLeadingZeroImpl(Storage word) {
return __builtin_clzll(static_cast<unsigned long long>(word)) - (BITSIZEOF(unsigned long long) - FlagsPerWord);
}
static constexpr ALWAYS_INLINE Storage GetBitMask(size_t bit) {
return Storage(1) << (FlagsPerWord - 1 - bit);
}
private:
Storage words[NumWords];
public:
constexpr ALWAYS_INLINE BitSet() : words() { /* ... */ }
constexpr ALWAYS_INLINE void SetBit(size_t i) {
this->words[i / FlagsPerWord] |= GetBitMask(i % FlagsPerWord);
}
constexpr ALWAYS_INLINE void ClearBit(size_t i) {
this->words[i / FlagsPerWord] &= ~GetBitMask(i % FlagsPerWord);
}
constexpr ALWAYS_INLINE size_t CountLeadingZero() const {
for (size_t i = 0; i < NumWords; i++) {
if (this->words[i]) {
return FlagsPerWord * i + CountLeadingZeroImpl(this->words[i]);
}
}
return FlagsPerWord * NumWords;
}
constexpr ALWAYS_INLINE size_t GetNextSet(size_t n) const {
for (size_t i = (n + 1) / FlagsPerWord; i < NumWords; i++) {
Storage word = this->words[i];
if (!util::IsAligned(n + 1, FlagsPerWord)) {
word &= GetBitMask(n % FlagsPerWord) - 1;
}
if (word) {
return FlagsPerWord * i + CountLeadingZeroImpl(word);
}
}
return FlagsPerWord * NumWords;
}
};
}
template<size_t N>
using BitSet8 = impl::BitSet<u8, N>;
template<size_t N>
using BitSet16 = impl::BitSet<u16, N>;
template<size_t N>
using BitSet32 = impl::BitSet<u32, N>;
template<size_t N>
using BitSet64 = impl::BitSet<u64, N>;
}