memory: Add class to manage and enforce memory freezing

src/core/memory/freezer.h

@@ -0,0 +1,58 @@
+// Copyright 2019 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <optional>
+#include <vector>
+#include "common/common_types.h"
+#include "core/core_timing.h"
+
+namespace Core {
+class System;
+} // namespace Core
+
+namespace Memory {
+
+// A class that will effectively freeze memory values.
+class Freezer {
+public:
+    struct Entry {
+        VAddr address;
+        u8 width;
+        u64 value;
+    };
+
+    Freezer(Core::Timing::CoreTiming& core_timing);
+    ~Freezer();
+
+    void SetActive(bool active);
+    bool IsActive() const;
+
+    void Clear();
+
+    u64 Freeze(VAddr address, u8 width);
+    void Unfreeze(VAddr address);
+
+    bool IsFrozen(VAddr address);
+    void SetFrozenValue(VAddr address, u64 value);
+
+    std::optional<Entry> GetEntry(VAddr address);
+
+    std::vector<Entry> GetEntries();
+
+private:
+    void FrameCallback(u64 userdata, s64 cycles_late);
+    void FillEntryReads();
+
+    std::atomic_bool active{false};
+
+    std::recursive_mutex entries_mutex;
+    std::vector<Entry> entries;
+
+    Core::Timing::EventType* event;
+    Core::Timing::CoreTiming& core_timing;
+};
+
+} // namespace Memory