citra/src/common/thunk.h

// Copyright 2013 Dolphin Emulator Project / 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#pragma once

#include <map>

#include "common/common.h"

// This simple class creates a wrapper around a C/C++ function that saves all fp state
// before entering it, and restores it upon exit. This is required to be able to selectively
// call functions from generated code, without inflicting the performance hit and increase
// of complexity that it means to protect the generated code from this problem.

// This process is called thunking.

// There will only ever be one level of thunking on the stack, plus,
// we don't want to pollute the stack, so we store away regs somewhere global.
// NOT THREAD SAFE. This may only be used from the CPU thread.
// Any other thread using this stuff will be FATAL.

class ThunkManager : public Gen::XCodeBlock
{
    std::map<void *, const u8 *> thunks;

    const u8 *save_regs;
    const u8 *load_regs;

public:
    ThunkManager() {
        Init();
    }
    ~ThunkManager() {
        Shutdown();
    }
    void *ProtectFunction(void *function, int num_params);
private:
    void Init();
    void Shutdown();
    void Reset();
};