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// Copyright 2020 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
// This file references various implementation details from Atmosphere, an open-source firmware for
// the Nintendo Switch. Copyright 2018-2020 Atmosphere-NX.
#pragma once
#include <atomic>
#include "common/assert.h"
#include "common/common_types.h"
namespace Kernel::Memory {
namespace impl {
class SlabHeapImpl final : NonCopyable {
public:
struct Node {
Node* next{};
};
constexpr SlabHeapImpl() = default;
void Initialize(std::size_t size) {
ASSERT(head == nullptr);
obj_size = size;
}
constexpr std::size_t GetObjectSize() const {
return obj_size;
}
Node* GetHead() const {
return head;
}
void* Allocate() {
Node* ret = head.load();
do {
if (ret == nullptr) {
break;
}
} while (!head.compare_exchange_weak(ret, ret->next));
return ret;
}
void Free(void* obj) {
Node* node = static_cast<Node*>(obj);
Node* cur_head = head.load();
do {
node->next = cur_head;
} while (!head.compare_exchange_weak(cur_head, node));
}
private:
std::atomic<Node*> head{};
std::size_t obj_size{};
};
} // namespace impl
class SlabHeapBase : NonCopyable {
public:
constexpr SlabHeapBase() = default;
constexpr bool Contains(uintptr_t addr) const {
return start <= addr && addr < end;
}
constexpr std::size_t GetSlabHeapSize() const {
return (end - start) / GetObjectSize();
}
constexpr std::size_t GetObjectSize() const {
return impl.GetObjectSize();
}
constexpr uintptr_t GetSlabHeapAddress() const {
return start;
}
std::size_t GetObjectIndexImpl(const void* obj) const {
return (reinterpret_cast<uintptr_t>(obj) - start) / GetObjectSize();
}
std::size_t GetPeakIndex() const {
return GetObjectIndexImpl(reinterpret_cast<const void*>(peak));
}
void* AllocateImpl() {
return impl.Allocate();
}
void FreeImpl(void* obj) {
// Don't allow freeing an object that wasn't allocated from this heap
ASSERT(Contains(reinterpret_cast<uintptr_t>(obj)));
impl.Free(obj);
}
void InitializeImpl(std::size_t obj_size, void* memory, std::size_t memory_size) {
// Ensure we don't initialize a slab using null memory
ASSERT(memory != nullptr);
// Initialize the base allocator
impl.Initialize(obj_size);
// Set our tracking variables
const std::size_t num_obj = (memory_size / obj_size);
start = reinterpret_cast<uintptr_t>(memory);
end = start + num_obj * obj_size;
peak = start;
// Free the objects
u8* cur = reinterpret_cast<u8*>(end);
for (std::size_t i{}; i < num_obj; i++) {
cur -= obj_size;
impl.Free(cur);
}
}
private:
using Impl = impl::SlabHeapImpl;
Impl impl;
uintptr_t peak{};
uintptr_t start{};
uintptr_t end{};
};
template <typename T>
class SlabHeap final : public SlabHeapBase {
public:
constexpr SlabHeap() : SlabHeapBase() {}
void Initialize(void* memory, std::size_t memory_size) {
InitializeImpl(sizeof(T), memory, memory_size);
}
T* Allocate() {
T* obj = static_cast<T*>(AllocateImpl());
if (obj != nullptr) {
new (obj) T();
}
return obj;
}
void Free(T* obj) {
FreeImpl(obj);
}
constexpr std::size_t GetObjectIndex(const T* obj) const {
return GetObjectIndexImpl(obj);
}
};
} // namespace Kernel::Memory
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