1 files changed, 82 insertions, 0 deletions

diff --git a/src/core/tools/freezer.h b/src/core/tools/freezer.h
new file mode 100644
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--- /dev/null
+++ b/src/core/tools/freezer.h
@@ -0,0 +1,82 @@
+// Copyright 2019 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <atomic>
+#include <mutex>
+#include <optional>
+#include <vector>
+#include "common/common_types.h"
+
+namespace Core::Timing {
+class CoreTiming;
+struct EventType;
+} // namespace Core::Timing
+
+namespace Tools {
+
+/**
+ * This class allows the user to prevent an application from writing new values to certain memory
+ * locations. This has a variety of uses when attempting to reverse a game.
+ *
+ * One example could be a cheat to prevent Mario from taking damage in SMO. One could freeze the
+ * memory address that the game uses to store Mario's health so when he takes damage (and the game
+ * tries to write the new health value to memory), the value won't change.
+ */
+class Freezer {
+public:
+    struct Entry {
+        VAddr address;
+        u32 width;
+        u64 value;
+    };
+
+    explicit Freezer(Core::Timing::CoreTiming& core_timing);
+    ~Freezer();
+
+    // Enables or disables the entire memory freezer.
+    void SetActive(bool active);
+
+    // Returns whether or not the freezer is active.
+    bool IsActive() const;
+
+    // Removes all entries from the freezer.
+    void Clear();
+
+    // Freezes a value to its current memory address. The value the memory is kept at will be the
+    // value that is read during this function. Width can be 1, 2, 4, or 8 (in bytes).
+    u64 Freeze(VAddr address, u32 width);
+
+    // Unfreezes the memory value at address. If the address isn't frozen, this is a no-op.
+    void Unfreeze(VAddr address);
+
+    // Returns whether or not the address is frozen.
+    bool IsFrozen(VAddr address) const;
+
+    // Sets the value that address should be frozen to. This doesn't change the width set by using
+    // Freeze(). If the value isn't frozen, this will not freeze it and is thus a no-op.
+    void SetFrozenValue(VAddr address, u64 value);
+
+    // Returns the entry corresponding to the address if the address is frozen, otherwise
+    // std::nullopt.
+    std::optional<Entry> GetEntry(VAddr address) const;
+
+    // Returns all the entries in the freezer, an empty vector means nothing is frozen.
+    std::vector<Entry> GetEntries() const;
+
+private:
+    void FrameCallback(u64 userdata, s64 cycles_late);
+    void FillEntryReads();
+
+    std::atomic_bool active{false};
+
+    mutable std::mutex entries_mutex;
+    std::vector<Entry> entries;
+
+    Core::Timing::EventType* event;
+    Core::Timing::CoreTiming& core_timing;
+};
+
+} // namespace Tools