/***********************************************************************************
  Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.

  (c) Copyright 1996 - 2002  Gary Henderson (gary.henderson@ntlworld.com),
                             Jerremy Koot (jkoot@snes9x.com)

  (c) Copyright 2002 - 2004  Matthew Kendora

  (c) Copyright 2002 - 2005  Peter Bortas (peter@bortas.org)

  (c) Copyright 2004 - 2005  Joel Yliluoma (http://iki.fi/bisqwit/)

  (c) Copyright 2001 - 2006  John Weidman (jweidman@slip.net)

  (c) Copyright 2002 - 2006  funkyass (funkyass@spam.shaw.ca),
                             Kris Bleakley (codeviolation@hotmail.com)

  (c) Copyright 2002 - 2010  Brad Jorsch (anomie@users.sourceforge.net),
                             Nach (n-a-c-h@users.sourceforge.net),

  (c) Copyright 2002 - 2011  zones (kasumitokoduck@yahoo.com)

  (c) Copyright 2006 - 2007  nitsuja

  (c) Copyright 2009 - 2018  BearOso,
                             OV2

  (c) Copyright 2017         qwertymodo

  (c) Copyright 2011 - 2017  Hans-Kristian Arntzen,
                             Daniel De Matteis
                             (Under no circumstances will commercial rights be given)


  BS-X C emulator code
  (c) Copyright 2005 - 2006  Dreamer Nom,
                             zones

  C4 x86 assembler and some C emulation code
  (c) Copyright 2000 - 2003  _Demo_ (_demo_@zsnes.com),
                             Nach,
                             zsKnight (zsknight@zsnes.com)

  C4 C++ code
  (c) Copyright 2003 - 2006  Brad Jorsch,
                             Nach

  DSP-1 emulator code
  (c) Copyright 1998 - 2006  _Demo_,
                             Andreas Naive (andreasnaive@gmail.com),
                             Gary Henderson,
                             Ivar (ivar@snes9x.com),
                             John Weidman,
                             Kris Bleakley,
                             Matthew Kendora,
                             Nach,
                             neviksti (neviksti@hotmail.com)

  DSP-2 emulator code
  (c) Copyright 2003         John Weidman,
                             Kris Bleakley,
                             Lord Nightmare (lord_nightmare@users.sourceforge.net),
                             Matthew Kendora,
                             neviksti

  DSP-3 emulator code
  (c) Copyright 2003 - 2006  John Weidman,
                             Kris Bleakley,
                             Lancer,
                             z80 gaiden

  DSP-4 emulator code
  (c) Copyright 2004 - 2006  Dreamer Nom,
                             John Weidman,
                             Kris Bleakley,
                             Nach,
                             z80 gaiden

  OBC1 emulator code
  (c) Copyright 2001 - 2004  zsKnight,
                             pagefault (pagefault@zsnes.com),
                             Kris Bleakley
                             Ported from x86 assembler to C by sanmaiwashi

  SPC7110 and RTC C++ emulator code used in 1.39-1.51
  (c) Copyright 2002         Matthew Kendora with research by
                             zsKnight,
                             John Weidman,
                             Dark Force

  SPC7110 and RTC C++ emulator code used in 1.52+
  (c) Copyright 2009         byuu,
                             neviksti

  S-DD1 C emulator code
  (c) Copyright 2003         Brad Jorsch with research by
                             Andreas Naive,
                             John Weidman

  S-RTC C emulator code
  (c) Copyright 2001 - 2006  byuu,
                             John Weidman

  ST010 C++ emulator code
  (c) Copyright 2003         Feather,
                             John Weidman,
                             Kris Bleakley,
                             Matthew Kendora

  Super FX x86 assembler emulator code
  (c) Copyright 1998 - 2003  _Demo_,
                             pagefault,
                             zsKnight

  Super FX C emulator code
  (c) Copyright 1997 - 1999  Ivar,
                             Gary Henderson,
                             John Weidman

  Sound emulator code used in 1.5-1.51
  (c) Copyright 1998 - 2003  Brad Martin
  (c) Copyright 1998 - 2006  Charles Bilyue'

  Sound emulator code used in 1.52+
  (c) Copyright 2004 - 2007  Shay Green (gblargg@gmail.com)

  S-SMP emulator code used in 1.54+
  (c) Copyright 2016         byuu

  SH assembler code partly based on x86 assembler code
  (c) Copyright 2002 - 2004  Marcus Comstedt (marcus@mc.pp.se)

  2xSaI filter
  (c) Copyright 1999 - 2001  Derek Liauw Kie Fa

  HQ2x, HQ3x, HQ4x filters
  (c) Copyright 2003         Maxim Stepin (maxim@hiend3d.com)

  NTSC filter
  (c) Copyright 2006 - 2007  Shay Green

  GTK+ GUI code
  (c) Copyright 2004 - 2018  BearOso

  Win32 GUI code
  (c) Copyright 2003 - 2006  blip,
                             funkyass,
                             Matthew Kendora,
                             Nach,
                             nitsuja
  (c) Copyright 2009 - 2018  OV2

  Mac OS GUI code
  (c) Copyright 1998 - 2001  John Stiles
  (c) Copyright 2001 - 2011  zones

  Libretro port
  (c) Copyright 2011 - 2017  Hans-Kristian Arntzen,
                             Daniel De Matteis
                             (Under no circumstances will commercial rights be given)


  Specific ports contains the works of other authors. See headers in
  individual files.


  Snes9x homepage: http://www.snes9x.com/

  Permission to use, copy, modify and/or distribute Snes9x in both binary
  and source form, for non-commercial purposes, is hereby granted without
  fee, providing that this license information and copyright notice appear
  with all copies and any derived work.

  This software is provided 'as-is', without any express or implied
  warranty. In no event shall the authors be held liable for any damages
  arising from the use of this software or it's derivatives.

  Snes9x is freeware for PERSONAL USE only. Commercial users should
  seek permission of the copyright holders first. Commercial use includes,
  but is not limited to, charging money for Snes9x or software derived from
  Snes9x, including Snes9x or derivatives in commercial game bundles, and/or
  using Snes9x as a promotion for your commercial product.

  The copyright holders request that bug fixes and improvements to the code
  should be forwarded to them so everyone can benefit from the modifications
  in future versions.

  Super NES and Super Nintendo Entertainment System are trademarks of
  Nintendo Co., Limited and its subsidiary companies.
 ***********************************************************************************/


#include "snes9x.h"
#include "memmap.h"
#include "cpuops.h"
#include "dma.h"
#include "apu/apu.h"
#include "fxemu.h"
#include "snapshot.h"
#ifdef DEBUGGER
#include "debug.h"
#include "missing.h"
#endif

static inline void S9xReschedule (void);


void S9xMainLoop (void)
{
	#define CHECK_FOR_IRQ_CHANGE() \
	if (Timings.IRQFlagChanging) \
	{ \
		if (Timings.IRQFlagChanging == IRQ_CLEAR_FLAG) \
			ClearIRQ(); \
		else if (Timings.IRQFlagChanging == IRQ_SET_FLAG) \
			SetIRQ(); \
		Timings.IRQFlagChanging = IRQ_NONE; \
	}

	for (;;)
	{
		if (CPU.NMIPending)
		{
			#ifdef DEBUGGER
			if (Settings.TraceHCEvent)
			    S9xTraceFormattedMessage ("Comparing %d to %d\n", Timings.NMITriggerPos, CPU.Cycles);
			#endif
			if (Timings.NMITriggerPos <= CPU.Cycles)
			{
				CPU.NMIPending = FALSE;
				Timings.NMITriggerPos = 0xffff;
				if (CPU.WaitingForInterrupt)
				{
					CPU.WaitingForInterrupt = FALSE;
					Registers.PCw++;
					CPU.Cycles += TWO_CYCLES + ONE_DOT_CYCLE / 2;
					while (CPU.Cycles >= CPU.NextEvent)
						S9xDoHEventProcessing();
				}

				CHECK_FOR_IRQ_CHANGE();
				S9xOpcode_NMI();
			}
		}

		if (CPU.Cycles >= Timings.NextIRQTimer)
		{
			#ifdef DEBUGGER
			S9xTraceMessage ("Timer triggered\n");
			#endif

			S9xUpdateIRQPositions(false);
			CPU.IRQLine = TRUE;
		}

		if (CPU.IRQLine || CPU.IRQExternal)
		{
			if (CPU.WaitingForInterrupt)
			{
				CPU.WaitingForInterrupt = FALSE;
				Registers.PCw++;
				CPU.Cycles += TWO_CYCLES + ONE_DOT_CYCLE / 2;
				while (CPU.Cycles >= CPU.NextEvent)
					S9xDoHEventProcessing();
			}

			if (!CheckFlag(IRQ))
			{
				/* The flag pushed onto the stack is the new value */
				CHECK_FOR_IRQ_CHANGE();
				S9xOpcode_IRQ();
			}
		}

		/* Change IRQ flag for instructions that set it only on last cycle */
		CHECK_FOR_IRQ_CHANGE();

	#ifdef DEBUGGER
		if ((CPU.Flags & BREAK_FLAG) && !(CPU.Flags & SINGLE_STEP_FLAG))
		{
			for (int Break = 0; Break != 6; Break++)
			{
				if (S9xBreakpoint[Break].Enabled &&
					S9xBreakpoint[Break].Bank == Registers.PB &&
					S9xBreakpoint[Break].Address == Registers.PCw)
				{
					if (S9xBreakpoint[Break].Enabled == 2)
						S9xBreakpoint[Break].Enabled = TRUE;
					else
						CPU.Flags |= DEBUG_MODE_FLAG;
				}
			}
		}

		if (CPU.Flags & DEBUG_MODE_FLAG)
			break;

		if (CPU.Flags & TRACE_FLAG)
			S9xTrace();

		if (CPU.Flags & SINGLE_STEP_FLAG)
		{
			CPU.Flags &= ~SINGLE_STEP_FLAG;
			CPU.Flags |= DEBUG_MODE_FLAG;
		}
	#endif

		if (CPU.Flags & SCAN_KEYS_FLAG)
			break;

		register uint8				Op;
		register struct	SOpcodes	*Opcodes;

		if (CPU.PCBase)
		{
			Op = CPU.PCBase[Registers.PCw];
			CPU.Cycles += CPU.MemSpeed;
			Opcodes = ICPU.S9xOpcodes;
		}
		else
		{
			Op = S9xGetByte(Registers.PBPC);
			OpenBus = Op;
			Opcodes = S9xOpcodesSlow;
		}

		if ((Registers.PCw & MEMMAP_MASK) + ICPU.S9xOpLengths[Op] >= MEMMAP_BLOCK_SIZE)
		{
			uint8	*oldPCBase = CPU.PCBase;

			CPU.PCBase = S9xGetBasePointer(ICPU.ShiftedPB + ((uint16) (Registers.PCw + 4)));
			if (oldPCBase != CPU.PCBase || (Registers.PCw & ~MEMMAP_MASK) == (0xffff & ~MEMMAP_MASK))
				Opcodes = S9xOpcodesSlow;
		}

		Registers.PCw++;
		(*Opcodes[Op].S9xOpcode)();

		if (Settings.SA1)
			S9xSA1MainLoop();
	}

	S9xPackStatus();

	if (CPU.Flags & SCAN_KEYS_FLAG)
	{
	#ifdef DEBUGGER
		if (!(CPU.Flags & FRAME_ADVANCE_FLAG))
	#endif
		S9xSyncSpeed();
		CPU.Flags &= ~SCAN_KEYS_FLAG;
	}
}

static inline void S9xReschedule (void)
{
	switch (CPU.WhichEvent)
	{
		case HC_HBLANK_START_EVENT:
			CPU.WhichEvent = HC_HDMA_START_EVENT;
			CPU.NextEvent  = Timings.HDMAStart;
			break;

		case HC_HDMA_START_EVENT:
			CPU.WhichEvent = HC_HCOUNTER_MAX_EVENT;
			CPU.NextEvent  = Timings.H_Max;
			break;

		case HC_HCOUNTER_MAX_EVENT:
			CPU.WhichEvent = HC_HDMA_INIT_EVENT;
			CPU.NextEvent  = Timings.HDMAInit;
			break;

		case HC_HDMA_INIT_EVENT:
			CPU.WhichEvent = HC_RENDER_EVENT;
			CPU.NextEvent  = Timings.RenderPos;
			break;

		case HC_RENDER_EVENT:
			CPU.WhichEvent = HC_WRAM_REFRESH_EVENT;
			CPU.NextEvent  = Timings.WRAMRefreshPos;
			break;

		case HC_WRAM_REFRESH_EVENT:
			CPU.WhichEvent = HC_HBLANK_START_EVENT;
			CPU.NextEvent  = Timings.HBlankStart;
			break;
	}
}

void S9xDoHEventProcessing (void)
{
#ifdef DEBUGGER
	static char	eventname[7][32] =
	{
		"",
		"HC_HBLANK_START_EVENT",
		"HC_HDMA_START_EVENT  ",
		"HC_HCOUNTER_MAX_EVENT",
		"HC_HDMA_INIT_EVENT   ",
		"HC_RENDER_EVENT      ",
		"HC_WRAM_REFRESH_EVENT"
	};
#endif

#ifdef DEBUGGER
	if (Settings.TraceHCEvent)
		S9xTraceFormattedMessage("--- HC event processing  (%s)  expected HC:%04d  executed HC:%04d VC:%04d",
			eventname[CPU.WhichEvent], CPU.NextEvent, CPU.Cycles, CPU.V_Counter);
#endif

	switch (CPU.WhichEvent)
	{
		case HC_HBLANK_START_EVENT:
			S9xReschedule();
			break;

		case HC_HDMA_START_EVENT:
			S9xReschedule();

			if (PPU.HDMA && CPU.V_Counter <= PPU.ScreenHeight)
			{
			#ifdef DEBUGGER
				S9xTraceFormattedMessage("*** HDMA Transfer HC:%04d, Channel:%02x", CPU.Cycles, PPU.HDMA);
			#endif
				PPU.HDMA = S9xDoHDMA(PPU.HDMA);
			}

			break;

		case HC_HCOUNTER_MAX_EVENT:
			if (Settings.SuperFX)
			{
				if (!SuperFX.oneLineDone)
					S9xSuperFXExec();
				SuperFX.oneLineDone = FALSE;
			}

			S9xAPUEndScanline();
			CPU.Cycles -= Timings.H_Max;
			if (Timings.NMITriggerPos != 0xffff)
				Timings.NMITriggerPos -= Timings.H_Max;
			if (Timings.NextIRQTimer != 0x0fffffff)
				Timings.NextIRQTimer -= Timings.H_Max;
			S9xAPUSetReferenceTime(CPU.Cycles);

			CPU.V_Counter++;
			if (CPU.V_Counter >= Timings.V_Max)	// V ranges from 0 to Timings.V_Max - 1
			{
				CPU.V_Counter = 0;
				Timings.InterlaceField ^= 1;

				// From byuu:
				// [NTSC]
				// interlace mode has 525 scanlines: 263 on the even frame, and 262 on the odd.
				// non-interlace mode has 524 scanlines: 262 scanlines on both even and odd frames.
				// [PAL] <PAL info is unverified on hardware>
				// interlace mode has 625 scanlines: 313 on the even frame, and 312 on the odd.
				// non-interlace mode has 624 scanlines: 312 scanlines on both even and odd frames.
				if (IPPU.Interlace && !Timings.InterlaceField)
					Timings.V_Max = Timings.V_Max_Master + 1;	// 263 (NTSC), 313?(PAL)
				else
					Timings.V_Max = Timings.V_Max_Master;		// 262 (NTSC), 312?(PAL)

				Memory.FillRAM[0x213F] ^= 0x80;
				PPU.RangeTimeOver = 0;

				// FIXME: reading $4210 will wait 2 cycles, then perform reading, then wait 4 more cycles.
				Memory.FillRAM[0x4210] = Model->_5A22;

				ICPU.Frame++;
				PPU.HVBeamCounterLatched = 0;
			}

			// From byuu:
			// In non-interlace mode, there are 341 dots per scanline, and 262 scanlines per frame.
			// On odd frames, scanline 240 is one dot short.
			// In interlace mode, there are always 341 dots per scanline. Even frames have 263 scanlines,
			// and odd frames have 262 scanlines.
			// Interlace mode scanline 240 on odd frames is not missing a dot.
			if (CPU.V_Counter == 240 && !IPPU.Interlace && Timings.InterlaceField)	// V=240
				Timings.H_Max = Timings.H_Max_Master - ONE_DOT_CYCLE;	// HC=1360
			else
				Timings.H_Max = Timings.H_Max_Master;					// HC=1364

			if (Model->_5A22 == 2)
			{
				if (CPU.V_Counter != 240 || IPPU.Interlace || !Timings.InterlaceField)	// V=240
				{
					if (Timings.WRAMRefreshPos == SNES_WRAM_REFRESH_HC_v2 - ONE_DOT_CYCLE)	// HC=534
						Timings.WRAMRefreshPos = SNES_WRAM_REFRESH_HC_v2;					// HC=538
					else
						Timings.WRAMRefreshPos = SNES_WRAM_REFRESH_HC_v2 - ONE_DOT_CYCLE;	// HC=534
				}
			}
			else
				Timings.WRAMRefreshPos = SNES_WRAM_REFRESH_HC_v1;

			if (CPU.V_Counter == PPU.ScreenHeight + FIRST_VISIBLE_LINE)	// VBlank starts from V=225(240).
			{
				S9xEndScreenRefresh();

				CPU.Flags |= SCAN_KEYS_FLAG;

				PPU.HDMA = 0;
				// Bits 7 and 6 of $4212 are computed when read in S9xGetPPU.
			#ifdef DEBUGGER
				missing.dma_this_frame = 0;
			#endif
				IPPU.MaxBrightness = PPU.Brightness;
				PPU.ForcedBlanking = (Memory.FillRAM[0x2100] >> 7) & 1;

				if (!PPU.ForcedBlanking)
				{
					PPU.OAMAddr = PPU.SavedOAMAddr;

					uint8	tmp = 0;

					if (PPU.OAMPriorityRotation)
						tmp = (PPU.OAMAddr & 0xFE) >> 1;
					if ((PPU.OAMFlip & 1) || PPU.FirstSprite != tmp)
					{
						PPU.FirstSprite = tmp;
						IPPU.OBJChanged = TRUE;
					}

					PPU.OAMFlip = 0;
				}

				// FIXME: writing to $4210 will wait 6 cycles.
				Memory.FillRAM[0x4210] = 0x80 | Model->_5A22;
				if (Memory.FillRAM[0x4200] & 0x80)
				{
#ifdef DEBUGGER
					if (Settings.TraceHCEvent)
					    S9xTraceFormattedMessage ("NMI Scheduled for next scanline.");
#endif
					// FIXME: triggered at HC=6, checked just before the final CPU cycle,
					// then, when to call S9xOpcode_NMI()?
					CPU.NMIPending = TRUE;
					Timings.NMITriggerPos = 8;
				}

			}

			if (CPU.V_Counter == PPU.ScreenHeight + 3)	// FIXME: not true
			{
				if (Memory.FillRAM[0x4200] & 1)
					S9xDoAutoJoypad();
			}

			if (CPU.V_Counter == FIRST_VISIBLE_LINE)	// V=1
				S9xStartScreenRefresh();

			S9xReschedule();

			break;

		case HC_HDMA_INIT_EVENT:
			S9xReschedule();

			if (CPU.V_Counter == 0)
			{
			#ifdef DEBUGGER
				S9xTraceFormattedMessage("*** HDMA Init     HC:%04d, Channel:%02x", CPU.Cycles, PPU.HDMA);
			#endif
				S9xStartHDMA();
			}

			break;

		case HC_RENDER_EVENT:
			if (CPU.V_Counter >= FIRST_VISIBLE_LINE && CPU.V_Counter <= PPU.ScreenHeight)
				RenderLine((uint8) (CPU.V_Counter - FIRST_VISIBLE_LINE));

			S9xReschedule();

			break;

		case HC_WRAM_REFRESH_EVENT:
		#ifdef DEBUGGER
			S9xTraceFormattedMessage("*** WRAM Refresh  HC:%04d", CPU.Cycles);
		#endif

			CPU.Cycles += SNES_WRAM_REFRESH_CYCLES;

			S9xReschedule();

			break;
	}

#ifdef DEBUGGER
	if (Settings.TraceHCEvent)
		S9xTraceFormattedMessage("--- HC event rescheduled (%s)  expected HC:%04d  current  HC:%04d",
			eventname[CPU.WhichEvent], CPU.NextEvent, CPU.Cycles);
#endif
}