/*  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 <atomic>

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);

    wxString m_name;

    uptr 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(const wxString &name, uptr base, size_t size, uptr upper_bounds = 0, bool strict = false);
    ~VirtualMemoryManager();

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

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

    void *AllocAtAddress(void *address, size_t size) const {
        return Alloc(size, (uptr)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<uptr> m_baseptr{0};
    const uptr m_endptr = 0;
public:
    VirtualMemoryBumpAllocator(VirtualMemoryManagerPtr allocator, size_t size, uptr offsetLocation);
    void *Alloc(size_t size);
    const VirtualMemoryManagerPtr& GetAllocator() { return m_allocator; }
};

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

protected:
    wxString m_name;

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

    // Default size of the reserve, in bytes.  Can be specified when the object is constructed.
    // Is used as the reserve size when Reserve() is called, unless an override is specified
    // in the Reserve parameters.
    size_t m_defsize;

    void *m_baseptr;

    // reserved memory (in pages).
    uptr m_pages_reserved;

    // Records the number of pages committed to memory.
    // (metric for analysis of buffer usage)
    uptr m_pages_commited;

    // Protection mode to be applied to committed blocks.
    PageProtectionMode m_prot_mode;

    // Controls write access to the entire reserve.  When true (the default), the reserve
    // operates normally.  When set to false, all committed blocks are re-protected with
    // write disabled, and accesses to uncommitted blocks (read or write) will cause a GPF
    // as well.
    bool m_allow_writes;

    // Allows the implementation to decide how much memory it needs to allocate if someone requests the given size
    // Should translate requests of size 0 to m_defsize
    virtual size_t GetSize(size_t requestedSize);

public:
    VirtualMemoryReserve(const wxString &name, size_t size = 0);
    virtual ~VirtualMemoryReserve()
    {
        Release();
    }

    // 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
    virtual void *Assign(VirtualMemoryManagerPtr allocator, void *baseptr, size_t size);

    void *Reserve(VirtualMemoryManagerPtr allocator, uptr baseOffset, size_t size = 0)
    {
        size = GetSize(size);
        void *allocation = allocator->Alloc(baseOffset, size);
        return Assign(std::move(allocator), allocation, size);
    }
    void *Reserve(VirtualMemoryBumpAllocator& allocator, size_t size = 0)
    {
        size = GetSize(size);
        return Assign(allocator.GetAllocator(), allocator.Alloc(size), size);
    }

    virtual void Reset();
    virtual void Release();
    virtual bool TryResize(uint newsize);
    virtual bool Commit();

    virtual void ForbidModification();
    virtual void AllowModification();

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

    uptr GetReserveSizeInBytes() const { return m_pages_reserved * __pagesize; }
    uptr GetReserveSizeInPages() const { return m_pages_reserved; }
    uint GetCommittedPageCount() const { return m_pages_commited; }
    uint GetCommittedBytes() const { return m_pages_commited * __pagesize; }

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

    VirtualMemoryReserve &SetPageAccessOnCommit(const PageProtectionMode &mode);

    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_pages_reserved * __pagesize));
        return *((u8 *)m_baseptr + idx);
    }

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

protected:
    virtual void ReprotectCommittedBlocks(const PageProtectionMode &newmode);
};

#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();

#include "Threading.h"
extern SrcType_PageFault *Source_PageFault;
extern Threading::Mutex PageFault_Mutex;