hle: kernel: Add KPageBitmap class.
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bunnei
parent
e7c33d1ad6
commit
a02566136c
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@ -164,6 +164,7 @@ add_library(core STATIC
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hle/kernel/k_light_condition_variable.h
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hle/kernel/k_light_lock.cpp
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hle/kernel/k_light_lock.h
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hle/kernel/k_page_bitmap.h
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hle/kernel/k_priority_queue.h
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hle/kernel/k_readable_event.cpp
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hle/kernel/k_readable_event.h
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@ -0,0 +1,279 @@
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// Copyright 2021 yuzu Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#pragma once
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#include <array>
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#include <bit>
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#include "common/alignment.h"
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#include "common/assert.h"
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#include "common/bit_util.h"
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#include "common/common_types.h"
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#include "common/tiny_mt.h"
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#include "core/hle/kernel/memory/system_control.h"
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namespace Kernel {
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class KPageBitmap {
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private:
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class RandomBitGenerator {
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private:
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Common::TinyMT rng{};
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u32 entropy{};
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u32 bits_available{};
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private:
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void RefreshEntropy() {
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entropy = rng.GenerateRandomU32();
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bits_available = static_cast<u32>(Common::BitSize<decltype(entropy)>());
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}
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bool GenerateRandomBit() {
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if (bits_available == 0) {
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this->RefreshEntropy();
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}
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const bool rnd_bit = (entropy & 1) != 0;
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entropy >>= 1;
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--bits_available;
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return rnd_bit;
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}
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public:
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RandomBitGenerator() {
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rng.Initialize(static_cast<u32>(Memory::SystemControl::GenerateRandomU64()));
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}
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std::size_t SelectRandomBit(u64 bitmap) {
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u64 selected = 0;
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u64 cur_num_bits = Common::BitSize<decltype(bitmap)>() / 2;
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u64 cur_mask = (1ULL << cur_num_bits) - 1;
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while (cur_num_bits) {
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const u64 low = (bitmap >> 0) & cur_mask;
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const u64 high = (bitmap >> cur_num_bits) & cur_mask;
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bool choose_low;
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if (high == 0) {
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// If only low val is set, choose low.
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choose_low = true;
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} else if (low == 0) {
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// If only high val is set, choose high.
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choose_low = false;
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} else {
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// If both are set, choose random.
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choose_low = this->GenerateRandomBit();
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}
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// If we chose low, proceed with low.
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if (choose_low) {
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bitmap = low;
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selected += 0;
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} else {
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bitmap = high;
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selected += cur_num_bits;
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}
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// Proceed.
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cur_num_bits /= 2;
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cur_mask >>= cur_num_bits;
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}
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return selected;
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}
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};
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public:
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static constexpr std::size_t MaxDepth = 4;
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private:
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std::array<u64*, MaxDepth> bit_storages{};
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RandomBitGenerator rng{};
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std::size_t num_bits{};
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std::size_t used_depths{};
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public:
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KPageBitmap() = default;
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constexpr std::size_t GetNumBits() const {
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return num_bits;
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}
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constexpr s32 GetHighestDepthIndex() const {
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return static_cast<s32>(used_depths) - 1;
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}
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u64* Initialize(u64* storage, std::size_t size) {
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// Initially, everything is un-set.
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num_bits = 0;
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// Calculate the needed bitmap depth.
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used_depths = static_cast<std::size_t>(GetRequiredDepth(size));
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ASSERT(used_depths <= MaxDepth);
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// Set the bitmap pointers.
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for (s32 depth = this->GetHighestDepthIndex(); depth >= 0; depth--) {
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bit_storages[depth] = storage;
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size = Common::AlignUp(size, Common::BitSize<u64>()) / Common::BitSize<u64>();
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storage += size;
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}
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return storage;
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}
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s64 FindFreeBlock(bool random) {
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uintptr_t offset = 0;
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s32 depth = 0;
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if (random) {
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do {
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const u64 v = bit_storages[depth][offset];
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if (v == 0) {
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// If depth is bigger than zero, then a previous level indicated a block was
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// free.
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ASSERT(depth == 0);
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return -1;
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}
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offset = offset * Common::BitSize<u64>() + rng.SelectRandomBit(v);
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++depth;
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} while (depth < static_cast<s32>(used_depths));
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} else {
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do {
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const u64 v = bit_storages[depth][offset];
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if (v == 0) {
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// If depth is bigger than zero, then a previous level indicated a block was
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// free.
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ASSERT(depth == 0);
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return -1;
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}
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offset = offset * Common::BitSize<u64>() + std::countr_zero(v);
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++depth;
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} while (depth < static_cast<s32>(used_depths));
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}
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return static_cast<s64>(offset);
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}
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void SetBit(std::size_t offset) {
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this->SetBit(this->GetHighestDepthIndex(), offset);
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num_bits++;
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}
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void ClearBit(std::size_t offset) {
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this->ClearBit(this->GetHighestDepthIndex(), offset);
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num_bits--;
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}
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bool ClearRange(std::size_t offset, std::size_t count) {
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s32 depth = this->GetHighestDepthIndex();
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u64* bits = bit_storages[depth];
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std::size_t bit_ind = offset / Common::BitSize<u64>();
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if (count < Common::BitSize<u64>()) {
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const std::size_t shift = offset % Common::BitSize<u64>();
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ASSERT(shift + count <= Common::BitSize<u64>());
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// Check that all the bits are set.
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const u64 mask = ((u64(1) << count) - 1) << shift;
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u64 v = bits[bit_ind];
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if ((v & mask) != mask) {
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return false;
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}
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// Clear the bits.
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v &= ~mask;
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bits[bit_ind] = v;
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if (v == 0) {
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this->ClearBit(depth - 1, bit_ind);
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}
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} else {
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ASSERT(offset % Common::BitSize<u64>() == 0);
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ASSERT(count % Common::BitSize<u64>() == 0);
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// Check that all the bits are set.
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std::size_t remaining = count;
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std::size_t i = 0;
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do {
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if (bits[bit_ind + i++] != ~u64(0)) {
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return false;
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}
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remaining -= Common::BitSize<u64>();
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} while (remaining > 0);
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// Clear the bits.
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remaining = count;
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i = 0;
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do {
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bits[bit_ind + i] = 0;
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this->ClearBit(depth - 1, bit_ind + i);
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i++;
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remaining -= Common::BitSize<u64>();
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} while (remaining > 0);
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}
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num_bits -= count;
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return true;
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}
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private:
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void SetBit(s32 depth, std::size_t offset) {
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while (depth >= 0) {
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std::size_t ind = offset / Common::BitSize<u64>();
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std::size_t which = offset % Common::BitSize<u64>();
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const u64 mask = u64(1) << which;
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u64* bit = std::addressof(bit_storages[depth][ind]);
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u64 v = *bit;
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ASSERT((v & mask) == 0);
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*bit = v | mask;
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if (v) {
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break;
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}
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offset = ind;
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depth--;
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}
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}
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void ClearBit(s32 depth, std::size_t offset) {
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while (depth >= 0) {
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std::size_t ind = offset / Common::BitSize<u64>();
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std::size_t which = offset % Common::BitSize<u64>();
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const u64 mask = u64(1) << which;
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u64* bit = std::addressof(bit_storages[depth][ind]);
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u64 v = *bit;
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ASSERT((v & mask) != 0);
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v &= ~mask;
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*bit = v;
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if (v) {
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break;
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}
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offset = ind;
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depth--;
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}
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}
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private:
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static constexpr s32 GetRequiredDepth(std::size_t region_size) {
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s32 depth = 0;
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while (true) {
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region_size /= Common::BitSize<u64>();
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depth++;
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if (region_size == 0) {
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return depth;
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}
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}
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}
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public:
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static constexpr std::size_t CalculateManagementOverheadSize(std::size_t region_size) {
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std::size_t overhead_bits = 0;
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for (s32 depth = GetRequiredDepth(region_size) - 1; depth >= 0; depth--) {
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region_size =
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Common::AlignUp(region_size, Common::BitSize<u64>()) / Common::BitSize<u64>();
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overhead_bits += region_size;
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}
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return overhead_bits * sizeof(u64);
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}
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};
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} // namespace Kernel
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