core/memory: Introduce skeleton of Memory class

Currently, the main memory management code is one of the remaining
places where we have global state. The next series of changes will aim
to rectify this.

This change simply introduces the main skeleton of the class that will
contain all the necessary state.

src/core/core.cpp

@@ -39,6 +39,7 @@
 #include "core/hle/service/service.h"
 #include "core/hle/service/sm/sm.h"
 #include "core/loader/loader.h"
+#include "core/memory.h"
 #include "core/memory/cheat_engine.h"
 #include "core/perf_stats.h"
 #include "core/reporter.h"
@@ -112,8 +113,8 @@ FileSys::VirtualFile GetGameFileFromPath(const FileSys::VirtualFilesystem& vfs,
 }
 struct System::Impl {
     explicit Impl(System& system)
-        : kernel{system}, fs_controller{system}, cpu_core_manager{system}, reporter{system},
-          applet_manager{system} {}
+        : kernel{system}, fs_controller{system}, memory{system},
+          cpu_core_manager{system}, reporter{system}, applet_manager{system} {}
 
     Cpu& CurrentCpuCore() {
         return cpu_core_manager.GetCurrentCore();
@@ -341,7 +342,8 @@ struct System::Impl {
     std::unique_ptr<VideoCore::RendererBase> renderer;
     std::unique_ptr<Tegra::GPU> gpu_core;
     std::shared_ptr<Tegra::DebugContext> debug_context;
-    std::unique_ptr<Core::Hardware::InterruptManager> interrupt_manager;
+    std::unique_ptr<Hardware::InterruptManager> interrupt_manager;
+    Memory::Memory memory;
     CpuCoreManager cpu_core_manager;
     bool is_powered_on = false;
     bool exit_lock = false;
@@ -498,6 +500,14 @@ const ExclusiveMonitor& System::Monitor() const {
     return impl->cpu_core_manager.GetExclusiveMonitor();
 }
 
+Memory::Memory& System::Memory() {
+    return impl->memory;
+}
+
+const Memory::Memory& System::Memory() const {
+    return impl->memory;
+}
+
 Tegra::GPU& System::GPU() {
     return *impl->gpu_core;
 }

src/core/core.h

@@ -86,6 +86,10 @@ namespace Core::Hardware {
 class InterruptManager;
 }
 
+namespace Memory {
+class Memory;
+}
+
 namespace Core {
 
 class ARM_Interface;
@@ -225,6 +229,12 @@ public:
     /// Gets a constant reference to the exclusive monitor
     const ExclusiveMonitor& Monitor() const;
 
+    /// Gets a mutable reference to the system memory instance.
+    Memory::Memory& Memory();
+
+    /// Gets a constant reference to the system memory instance.
+    const Memory::Memory& Memory() const;
+
     /// Gets a mutable reference to the GPU interface
     Tegra::GPU& GPU();
 

src/core/memory.cpp

@@ -24,6 +24,18 @@ namespace Memory {
 
 static Common::PageTable* current_page_table = nullptr;
 
+// Implementation class used to keep the specifics of the memory subsystem hidden
+// from outside classes. This also allows modification to the internals of the memory
+// subsystem without needing to rebuild all files that make use of the memory interface.
+struct Memory::Impl {
+    explicit Impl(Core::System& system_) : system{system_} {}
+
+    Core::System& system;
+};
+
+Memory::Memory(Core::System& system) : impl{std::make_unique<Impl>(system)} {}
+Memory::~Memory() = default;
+
 void SetCurrentPageTable(Kernel::Process& process) {
     current_page_table = &process.VMManager().page_table;
 

src/core/memory.h

@@ -8,6 +8,10 @@
 #include <string>
 #include "common/common_types.h"
 
+namespace Core {
+class System;
+}
+
 namespace Kernel {
 class Process;
 }
@@ -36,6 +40,23 @@ enum : VAddr {
     KERNEL_REGION_END = KERNEL_REGION_VADDR + KERNEL_REGION_SIZE,
 };
 
+/// Central class that handles all memory operations and state.
+class Memory {
+public:
+    explicit Memory(Core::System& system);
+    ~Memory();
+
+    Memory(const Memory&) = delete;
+    Memory& operator=(const Memory&) = delete;
+
+    Memory(Memory&&) = default;
+    Memory& operator=(Memory&&) = default;
+
+private:
+    struct Impl;
+    std::unique_ptr<Impl> impl;
+};
+
 /// Changes the currently active page table to that of
 /// the given process instance.
 void SetCurrentPageTable(Kernel::Process& process);