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src/common/page_table.h

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+// Copyright 2019 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <tuple>
+
+#include "common/common_types.h"
+#include "common/memory_hook.h"
+#include "common/virtual_buffer.h"
+
+namespace Common {
+
+enum class PageType : u8 {
+    /// Page is unmapped and should cause an access error.
+    Unmapped,
+    /// Page is mapped to regular memory. This is the only type you can get pointers to.
+    Memory,
+    /// Page is mapped to regular memory, but also needs to check for rasterizer cache flushing and
+    /// invalidation
+    RasterizerCachedMemory,
+    /// Page is mapped to a I/O region. Writing and reading to this page is handled by functions.
+    Special,
+    /// Page is allocated for use.
+    Allocated,
+};
+
+struct SpecialRegion {
+    enum class Type {
+        DebugHook,
+        IODevice,
+    } type;
+
+    MemoryHookPointer handler;
+
+    [[nodiscard]] bool operator<(const SpecialRegion& other) const {
+        return std::tie(type, handler) < std::tie(other.type, other.handler);
+    }
+
+    [[nodiscard]] bool operator==(const SpecialRegion& other) const {
+        return std::tie(type, handler) == std::tie(other.type, other.handler);
+    }
+};
+
+/**
+ * A (reasonably) fast way of allowing switchable and remappable process address spaces. It loosely
+ * mimics the way a real CPU page table works.
+ */
+struct PageTable {
+    PageTable();
+    ~PageTable() noexcept;
+
+    PageTable(const PageTable&) = delete;
+    PageTable& operator=(const PageTable&) = delete;
+
+    PageTable(PageTable&&) noexcept = default;
+    PageTable& operator=(PageTable&&) noexcept = default;
+
+    /**
+     * Resizes the page table to be able to accomodate enough pages within
+     * a given address space.
+     *
+     * @param address_space_width_in_bits The address size width in bits.
+     * @param page_size_in_bits           The page size in bits.
+     * @param has_attribute               Whether or not this page has any backing attributes.
+     */
+    void Resize(std::size_t address_space_width_in_bits, std::size_t page_size_in_bits,
+                bool has_attribute);
+
+    /**
+     * Vector of memory pointers backing each page. An entry can only be non-null if the
+     * corresponding entry in the `attributes` vector is of type `Memory`.
+     */
+    VirtualBuffer<u8*> pointers;
+
+    VirtualBuffer<u64> backing_addr;
+
+    VirtualBuffer<PageType> attributes;
+};
+
+} // namespace Common