From d364e7cf09ee8de31610bc606e69ded6bfa94c18 Mon Sep 17 00:00:00 2001
From: bunnei <bunneidev@gmail.com>
Date: Sun, 5 Apr 2020 14:41:04 -0400
Subject: kernel: memory: Add SlabHeap class, for managing memory heaps.

- This will be used for TLS pages, among other things.
---
 src/core/hle/kernel/memory/slab_heap.h | 161 +++++++++++++++++++++++++++++++++
 1 file changed, 161 insertions(+)
 create mode 100644 src/core/hle/kernel/memory/slab_heap.h

(limited to 'src/core/hle/kernel')

diff --git a/src/core/hle/kernel/memory/slab_heap.h b/src/core/hle/kernel/memory/slab_heap.h
new file mode 100644
index 000000000..ca334384b
--- /dev/null
+++ b/src/core/hle/kernel/memory/slab_heap.h
@@ -0,0 +1,161 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <atomic>
+
+#include "common/assert.h"
+#include "common/common_funcs.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 = reinterpret_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 = reinterpret_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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