/*
    Copyright 2016-2023 melonDS team

    This file is part of melonDS.

    melonDS is free software: you can redistribute it and/or modify it under
    the terms of the GNU General Public License as published by the Free
    Software Foundation, either version 3 of the License, or (at your option)
    any later version.

    melonDS 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 melonDS. If not, see http://www.gnu.org/licenses/.
*/

#ifndef ARM_H
#define ARM_H

#include <algorithm>

#include "types.h"
#include "NDS.h"

#ifdef GDBSTUB_ENABLED
#include "debug/GdbStub.h"
#endif

inline u32 ROR(u32 x, u32 n)
{
    return (x >> (n&0x1F)) | (x << ((32-n)&0x1F));
}

enum
{
    RWFlags_Nonseq = (1<<5),
    RWFlags_ForceUser = (1<<21),
};

const u32 ITCMPhysicalSize = 0x8000;
const u32 DTCMPhysicalSize = 0x4000;

class ARM
#ifdef GDBSTUB_ENABLED
    : public Gdb::StubCallbacks
#endif
{
public:
    ARM(u32 num);
    virtual ~ARM(); // destroy shit

    virtual void Reset();

    virtual void DoSavestate(Savestate* file);

    virtual void FillPipeline() = 0;

    virtual void JumpTo(u32 addr, bool restorecpsr = false) = 0;
    void RestoreCPSR();

    void Halt(u32 halt)
    {
        if (halt==2 && Halted==1) return;
        Halted = halt;
    }

    virtual void Execute() = 0;
#ifdef JIT_ENABLED
    virtual void ExecuteJIT() = 0;
#endif

    bool CheckCondition(u32 code)
    {
        if (code == 0xE) return true;
        if (ConditionTable[code] & (1 << (CPSR>>28))) return true;
        return false;
    }

    void SetC(bool c)
    {
        if (c) CPSR |= 0x20000000;
        else CPSR &= ~0x20000000;
    }

    void SetNZ(bool n, bool z)
    {
        CPSR &= ~0xC0000000;
        if (n) CPSR |= 0x80000000;
        if (z) CPSR |= 0x40000000;
    }

    void SetNZCV(bool n, bool z, bool c, bool v)
    {
        CPSR &= ~0xF0000000;
        if (n) CPSR |= 0x80000000;
        if (z) CPSR |= 0x40000000;
        if (c) CPSR |= 0x20000000;
        if (v) CPSR |= 0x10000000;
    }

    inline bool ModeIs(u32 mode)
    {
        u32 cm = CPSR & 0x1f;
        mode &= 0x1f;

        if (mode == cm) return true;
        if (mode == 0x17) return cm >= 0x14 && cm <= 0x17; // abt
        if (mode == 0x1b) return cm >= 0x18 && cm <= 0x1b; // und

        return false;
    }

    void UpdateMode(u32 oldmode, u32 newmode, bool phony = false);

    void TriggerIRQ();

    void SetupCodeMem(u32 addr);


    virtual void DataRead8(u32 addr, u32* val) = 0;
    virtual void DataRead16(u32 addr, u32* val) = 0;
    virtual void DataRead32(u32 addr, u32* val) = 0;
    virtual void DataRead32S(u32 addr, u32* val) = 0;
    virtual void DataWrite8(u32 addr, u8 val) = 0;
    virtual void DataWrite16(u32 addr, u16 val) = 0;
    virtual void DataWrite32(u32 addr, u32 val) = 0;
    virtual void DataWrite32S(u32 addr, u32 val) = 0;

    virtual void AddCycles_C() = 0;
    virtual void AddCycles_CI(s32 numI) = 0;
    virtual void AddCycles_CDI() = 0;
    virtual void AddCycles_CD() = 0;

    void CheckGdbIncoming();

    u32 Num;

    s32 Cycles;
    union
    {
        struct
        {
            u8 Halted;
            u8 IRQ; // nonzero to trigger IRQ
            u8 IdleLoop;
        };
        u32 StopExecution;
    };

    u32 CodeRegion;
    s32 CodeCycles;

    u32 DataRegion;
    s32 DataCycles;

    u32 R[16]; // heh
    u32 CPSR;
    u32 R_FIQ[8]; // holding SPSR too
    u32 R_SVC[3];
    u32 R_ABT[3];
    u32 R_IRQ[3];
    u32 R_UND[3];
    u32 CurInstr;
    u32 NextInstr[2];

    u32 ExceptionBase;

    NDS::MemRegion CodeMem;

#ifdef JIT_ENABLED
    u32 FastBlockLookupStart, FastBlockLookupSize;
    u64* FastBlockLookup;
#endif

    static u32 ConditionTable[16];
#ifdef GDBSTUB_ENABLED
    Gdb::GdbStub GdbStub;
#endif

protected:
    u8 (*BusRead8)(u32 addr);
    u16 (*BusRead16)(u32 addr);
    u32 (*BusRead32)(u32 addr);
    void (*BusWrite8)(u32 addr, u8 val);
    void (*BusWrite16)(u32 addr, u16 val);
    void (*BusWrite32)(u32 addr, u32 val);

#ifdef GDBSTUB_ENABLED
    bool IsSingleStep;
    bool BreakReq;
    bool BreakOnStartup;

public:
    int GetCPU() const override { return Num ? 7 : 9; }

    u32 ReadReg(Gdb::Register reg) override;
    void WriteReg(Gdb::Register reg, u32 v) override;
    u32 ReadMem(u32 addr, int size) override;
    void WriteMem(u32 addr, int size, u32 v) override;

    void ResetGdb() override;
    int RemoteCmd(const u8* cmd, size_t len) override;

protected:
#endif

    void GdbCheckA();
    void GdbCheckB();
    void GdbCheckC();
};

class ARMv5 : public ARM
{
public:
    ARMv5();
    ~ARMv5();

    void Reset() override;

    void DoSavestate(Savestate* file) override;

    void UpdateRegionTimings(u32 addrstart, u32 addrend);

    void FillPipeline() override;

    void JumpTo(u32 addr, bool restorecpsr = false) override;

    void PrefetchAbort();
    void DataAbort();

    void Execute() override;
#ifdef JIT_ENABLED
    void ExecuteJIT() override;
#endif

    // all code accesses are forced nonseq 32bit
    u32 CodeRead32(u32 addr, bool branch);

    void DataRead8(u32 addr, u32* val) override;
    void DataRead16(u32 addr, u32* val) override;
    void DataRead32(u32 addr, u32* val) override;
    void DataRead32S(u32 addr, u32* val) override;
    void DataWrite8(u32 addr, u8 val) override;
    void DataWrite16(u32 addr, u16 val) override;
    void DataWrite32(u32 addr, u32 val) override;
    void DataWrite32S(u32 addr, u32 val) override;

    void AddCycles_C() override
    {
        // code only. always nonseq 32-bit for ARM9.
        s32 numC = (R[15] & 0x2) ? 0 : CodeCycles;
        Cycles += numC;
    }

    void AddCycles_CI(s32 numI) override
    {
        // code+internal
        s32 numC = (R[15] & 0x2) ? 0 : CodeCycles;
        Cycles += numC + numI;
    }

    void AddCycles_CDI() override
    {
        // LDR/LDM cycles. ARM9 seems to skip the internal cycle there.
        // TODO: ITCM data fetches shouldn't be parallelized, they say
        s32 numC = (R[15] & 0x2) ? 0 : CodeCycles;
        s32 numD = DataCycles;

        //if (DataRegion != CodeRegion)
            Cycles += std::max(numC + numD - 6, std::max(numC, numD));
        //else
        //    Cycles += numC + numD;
    }

    void AddCycles_CD() override
    {
        // TODO: ITCM data fetches shouldn't be parallelized, they say
        s32 numC = (R[15] & 0x2) ? 0 : CodeCycles;
        s32 numD = DataCycles;

        //if (DataRegion != CodeRegion)
            Cycles += std::max(numC + numD - 6, std::max(numC, numD));
        //else
        //    Cycles += numC + numD;
    }

    void GetCodeMemRegion(u32 addr, NDS::MemRegion* region);

    void CP15Reset();
    void CP15DoSavestate(Savestate* file);

    void UpdateDTCMSetting();
    void UpdateITCMSetting();

    void UpdatePURegion(u32 n);
    void UpdatePURegions(bool update_all);

    u32 RandomLineIndex();

    void ICacheLookup(u32 addr);
    void ICacheInvalidateByAddr(u32 addr);
    void ICacheInvalidateAll();

    void CP15Write(u32 id, u32 val);
    u32 CP15Read(u32 id);

    u32 CP15Control;

    u32 RNGSeed;

    u32 DTCMSetting, ITCMSetting;

    // for aarch64 JIT they need to go up here
    // to be addressable by a 12-bit immediate
    u32 ITCMSize;
    u32 DTCMBase, DTCMMask;
    s32 RegionCodeCycles;

    u8 ITCM[ITCMPhysicalSize];
    u8* DTCM;

    u8 ICache[0x2000];
    u32 ICacheTags[64*4];
    u8 ICacheCount[64];

    u32 PU_CodeCacheable;
    u32 PU_DataCacheable;
    u32 PU_DataCacheWrite;

    u32 PU_CodeRW;
    u32 PU_DataRW;

    u32 PU_Region[8];

    // 0=dataR 1=dataW 2=codeR 4=datacache 5=datawrite 6=codecache
    u8 PU_PrivMap[0x100000];
    u8 PU_UserMap[0x100000];

    // games operate under system mode, generally
    //#define PU_Map PU_PrivMap
    u8* PU_Map;

    // code/16N/32N/32S
    u8 MemTimings[0x100000][4];

    u8* CurICacheLine;

    bool (*GetMemRegion)(u32 addr, bool write, NDS::MemRegion* region);

#ifdef GDBSTUB_ENABLED
    u32 ReadMem(u32 addr, int size) override;
    void WriteMem(u32 addr, int size, u32 v) override;
#endif
};

class ARMv4 : public ARM
{
public:
    ARMv4();

    void Reset() override;

    void FillPipeline() override;

    void JumpTo(u32 addr, bool restorecpsr = false) override;

    void Execute() override;
#ifdef JIT_ENABLED
    void ExecuteJIT() override;
#endif

    u16 CodeRead16(u32 addr)
    {
        return BusRead16(addr);
    }

    u32 CodeRead32(u32 addr)
    {
        return BusRead32(addr);
    }

    void DataRead8(u32 addr, u32* val) override
    {
        *val = BusRead8(addr);
        DataRegion = addr;
        DataCycles = NDS::ARM7MemTimings[addr >> 15][0];
    }

    void DataRead16(u32 addr, u32* val) override
    {
        addr &= ~1;

        *val = BusRead16(addr);
        DataRegion = addr;
        DataCycles = NDS::ARM7MemTimings[addr >> 15][0];
    }

    void DataRead32(u32 addr, u32* val) override
    {
        addr &= ~3;

        *val = BusRead32(addr);
        DataRegion = addr;
        DataCycles = NDS::ARM7MemTimings[addr >> 15][2];
    }

    void DataRead32S(u32 addr, u32* val) override
    {
        addr &= ~3;

        *val = BusRead32(addr);
        DataCycles += NDS::ARM7MemTimings[addr >> 15][3];
    }

    void DataWrite8(u32 addr, u8 val) override
    {
        BusWrite8(addr, val);
        DataRegion = addr;
        DataCycles = NDS::ARM7MemTimings[addr >> 15][0];
    }

    void DataWrite16(u32 addr, u16 val) override
    {
        addr &= ~1;

        BusWrite16(addr, val);
        DataRegion = addr;
        DataCycles = NDS::ARM7MemTimings[addr >> 15][0];
    }

    void DataWrite32(u32 addr, u32 val) override
    {
        addr &= ~3;

        BusWrite32(addr, val);
        DataRegion = addr;
        DataCycles = NDS::ARM7MemTimings[addr >> 15][2];
    }

    void DataWrite32S(u32 addr, u32 val) override
    {
        addr &= ~3;

        BusWrite32(addr, val);
        DataCycles += NDS::ARM7MemTimings[addr >> 15][3];
    }


    void AddCycles_C() override
    {
        // code only. this code fetch is sequential.
        Cycles += NDS::ARM7MemTimings[CodeCycles][(CPSR&0x20)?1:3];
    }

    void AddCycles_CI(s32 num) override
    {
        // code+internal. results in a nonseq code fetch.
        Cycles += NDS::ARM7MemTimings[CodeCycles][(CPSR&0x20)?0:2] + num;
    }

    void AddCycles_CDI() override
    {
        // LDR/LDM cycles.
        s32 numC = NDS::ARM7MemTimings[CodeCycles][(CPSR&0x20)?0:2];
        s32 numD = DataCycles;

        if ((DataRegion >> 24) == 0x02) // mainRAM
        {
            if (CodeRegion == 0x02)
                Cycles += numC + numD;
            else
            {
                numC++;
                Cycles += std::max(numC + numD - 3, std::max(numC, numD));
            }
        }
        else if (CodeRegion == 0x02)
        {
            numD++;
            Cycles += std::max(numC + numD - 3, std::max(numC, numD));
        }
        else
        {
            Cycles += numC + numD + 1;
        }
    }

    void AddCycles_CD() override
    {
        // TODO: max gain should be 5c when writing to mainRAM
        s32 numC = NDS::ARM7MemTimings[CodeCycles][(CPSR&0x20)?0:2];
        s32 numD = DataCycles;

        if ((DataRegion >> 24) == 0x02)
        {
            if (CodeRegion == 0x02)
                Cycles += numC + numD;
            else
                Cycles += std::max(numC + numD - 3, std::max(numC, numD));
        }
        else if (CodeRegion == 0x02)
        {
            Cycles += std::max(numC + numD - 3, std::max(numC, numD));
        }
        else
        {
            Cycles += numC + numD;
        }
    }
};

namespace ARMInterpreter
{

void A_UNK(ARM* cpu);
void T_UNK(ARM* cpu);

}

namespace NDS
{

extern ARMv5* ARM9;
extern ARMv4* ARM7;

}

#endif // ARM_H