/*  PCSX2 - PS2 Emulator for PCs
 *  Copyright (C) 2002-2010  PCSX2 Dev Team
 *
 *  PCSX2 is free software: you can redistribute it and/or modify it under the terms
 *  of the GNU Lesser General Public License as published by the Free Software Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  PCSX2 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *  PURPOSE.  See the GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along with PCSX2.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

// [TODO] Rename this file to VirtualMemory.h !!

#pragma once

// =====================================================================================================
//  Cross-Platform Memory Protection (Used by VTLB, Recompilers and Texture caches)
// =====================================================================================================
// Win32 platforms use the SEH model: __try {}  __except {}
// Linux platforms use the POSIX Signals model: sigaction()
// [TODO] OS-X (Darwin) platforms should use the Mach exception model (not implemented)

#include "EventSource.h"
#include "General.h"
#include "Assertions.h"
#include <atomic>
#include <memory>
#include <mutex>
#include <string>

struct PageFaultInfo
{
	uptr addr;

	PageFaultInfo(uptr address)
	{
		addr = address;
	}
};

// --------------------------------------------------------------------------------------
//  IEventListener_PageFault
// --------------------------------------------------------------------------------------
class IEventListener_PageFault : public IEventDispatcher<PageFaultInfo>
{
public:
	typedef PageFaultInfo EvtParams;

public:
	virtual ~IEventListener_PageFault() = default;

	virtual void DispatchEvent(const PageFaultInfo& evtinfo, bool& handled)
	{
		OnPageFaultEvent(evtinfo, handled);
	}

	virtual void DispatchEvent(const PageFaultInfo& evtinfo)
	{
		pxFailRel("Don't call me, damnit.  Use DispatchException instead.");
	}

	virtual void OnPageFaultEvent(const PageFaultInfo& evtinfo, bool& handled) {}
};

// --------------------------------------------------------------------------------------
//  EventListener_PageFault / EventListenerHelper_PageFault
// --------------------------------------------------------------------------------------
class EventListener_PageFault : public IEventListener_PageFault
{
public:
	EventListener_PageFault();
	virtual ~EventListener_PageFault();
};

template <typename TypeToDispatchTo>
class EventListenerHelper_PageFault : public EventListener_PageFault
{
public:
	TypeToDispatchTo* Owner;

public:
	EventListenerHelper_PageFault(TypeToDispatchTo& dispatchTo)
	{
		Owner = &dispatchTo;
	}

	EventListenerHelper_PageFault(TypeToDispatchTo* dispatchTo)
	{
		Owner = dispatchTo;
	}

	virtual ~EventListenerHelper_PageFault() = default;

protected:
	virtual void OnPageFaultEvent(const PageFaultInfo& info, bool& handled)
	{
		Owner->OnPageFaultEvent(info, handled);
	}
};

// --------------------------------------------------------------------------------------
//  SrcType_PageFault
// --------------------------------------------------------------------------------------
class SrcType_PageFault : public EventSource<IEventListener_PageFault>
{
protected:
	typedef EventSource<IEventListener_PageFault> _parent;

protected:
	bool m_handled;

public:
	SrcType_PageFault()
		: m_handled(false)
	{
	}
	virtual ~SrcType_PageFault() = default;

	bool WasHandled() const { return m_handled; }
	virtual void Dispatch(const PageFaultInfo& params);

protected:
	virtual void _DispatchRaw(ListenerIterator iter, const ListenerIterator& iend, const PageFaultInfo& evt);
};


// --------------------------------------------------------------------------------------
//  VirtualMemoryManager: Manages the allocation of PCSX2 VM
//    Ensures that all memory is close enough together for rip-relative addressing
// --------------------------------------------------------------------------------------
class VirtualMemoryManager
{
	DeclareNoncopyableObject(VirtualMemoryManager);

	std::string m_name;

	void* m_file_handle;
	u8* m_baseptr;

	// An array to track page usage (to trigger asserts if things try to overlap)
	std::atomic<bool>* m_pageuse;

	// reserved memory (in pages)
	u32 m_pages_reserved;

public:
	// If upper_bounds is nonzero and the OS fails to allocate memory that is below it,
	// calls to IsOk() will return false and Alloc() will always return null pointers
	// strict indicates that the allocation should quietly fail if the memory can't be mapped at `base`
	VirtualMemoryManager(std::string name, const char* file_mapping_name, uptr base, size_t size, uptr upper_bounds = 0, bool strict = false);
	~VirtualMemoryManager();

	bool IsSharedMemory() const { return (m_file_handle != nullptr); }
	void* GetFileHandle() const { return m_file_handle; }
	u8* GetBase() const { return m_baseptr; }
	u8* GetEnd() const { return (m_baseptr + m_pages_reserved * __pagesize); }

	// Request the use of the memory at offsetLocation bytes from the start of the reserved memory area
	// offsetLocation must be page-aligned
	u8* Alloc(uptr offsetLocation, size_t size) const;

	u8* AllocAtAddress(void* address, size_t size) const
	{
		return Alloc(size, static_cast<const u8*>(address) - m_baseptr);
	}

	void Free(void* address, size_t size) const;

	// Was this VirtualMemoryManager successfully able to get its memory mapping?
	// (If not, calls to Alloc will return null pointers)
	bool IsOk() const { return m_baseptr != 0; }
};

typedef std::shared_ptr<const VirtualMemoryManager> VirtualMemoryManagerPtr;

// --------------------------------------------------------------------------------------
//  VirtualMemoryBumpAllocator: Allocates memory for things that don't have explicitly-reserved spots
// --------------------------------------------------------------------------------------
class VirtualMemoryBumpAllocator
{
	const VirtualMemoryManagerPtr m_allocator;
	std::atomic<u8*> m_baseptr{0};
	const u8* m_endptr = 0;

public:
	VirtualMemoryBumpAllocator(VirtualMemoryManagerPtr allocator, size_t size, uptr offsetLocation);
	u8* Alloc(size_t size);
	const VirtualMemoryManagerPtr& GetAllocator() { return m_allocator; }
};

// --------------------------------------------------------------------------------------
//  VirtualMemoryReserve
// --------------------------------------------------------------------------------------
class VirtualMemoryReserve
{
	DeclareNoncopyableObject(VirtualMemoryReserve);

protected:
	std::string m_name;

	// Where the memory came from (so we can return it)
	VirtualMemoryManagerPtr m_allocator;

	u8* m_baseptr = nullptr;
	size_t m_size = 0;

public:
	VirtualMemoryReserve(std::string name);
	virtual ~VirtualMemoryReserve();

	// Initialize with the given piece of memory
	// Note: The memory is already allocated, the allocator is for future use to free the region
	// It may be null in which case there is no way to free the memory in a way it will be usable again
	void Assign(VirtualMemoryManagerPtr allocator, u8* baseptr, size_t size);

	u8* BumpAllocate(VirtualMemoryBumpAllocator& allocator, size_t size);

	void Release();

	bool IsOk() const { return m_baseptr != NULL; }
	const std::string& GetName() const { return m_name; }

	u8* GetPtr() { return m_baseptr; }
	const u8* GetPtr() const { return m_baseptr; }
	u8* GetPtrEnd() { return m_baseptr + m_size; }
	const u8* GetPtrEnd() const { return m_baseptr + m_size; }

	size_t GetSize() const { return m_size; }

	operator void*() { return m_baseptr; }
	operator const void*() const { return m_baseptr; }

	operator u8*() { return (u8*)m_baseptr; }
	operator const u8*() const { return (u8*)m_baseptr; }

	u8& operator[](uint idx)
	{
		pxAssert(idx < m_size);
		return *((u8*)m_baseptr + idx);
	}

	const u8& operator[](uint idx) const
	{
		pxAssert(idx < m_size);
		return *((u8*)m_baseptr + idx);
	}
};

#ifdef __POSIX__

#define PCSX2_PAGEFAULT_PROTECT
#define PCSX2_PAGEFAULT_EXCEPT

#elif defined(_WIN32)

struct _EXCEPTION_POINTERS;
extern long __stdcall SysPageFaultExceptionFilter(struct _EXCEPTION_POINTERS* eps);

#define PCSX2_PAGEFAULT_PROTECT __try
#define PCSX2_PAGEFAULT_EXCEPT \
	__except (SysPageFaultExceptionFilter(GetExceptionInformation())) {}

#else
#error PCSX2 - Unsupported operating system platform.
#endif

extern void pxInstallSignalHandler();
extern void _platform_InstallSignalHandler();

extern SrcType_PageFault* Source_PageFault;
extern std::mutex PageFault_Mutex;