// SPDX-FileCopyrightText: 2002-2024 PCSX2 Dev Team
// SPDX-License-Identifier: GPL-3.0+

#define _PC_	// disables MIPS opcode macros.

#include "R3000A.h"
#include "Common.h"
#include "Sif.h"
#include "IopHw.h"

_sif sif0;

static bool done = false;

static __fi void Sif0Init()
{
	SIF_LOG("SIF0 DMA start...");
	done = false;
	sif0.ee.cycles = 0;
	sif0.iop.cycles = 0;
}

// Write from Fifo to EE.
static __fi bool WriteFifoToEE()
{
	const int readSize = std::min((s32)sif0ch.qwc, sif0.fifo.size >> 2);

	tDMA_TAG *ptag;

	//SIF_LOG(" EE SIF doing transfer %04Xqw to %08X", readSize, sif0ch.madr);
	SIF_LOG("Write Fifo to EE: ----------- %lX of %lX", readSize << 2, sif0ch.qwc << 2);

	ptag = sif0ch.getAddr(sif0ch.madr, DMAC_SIF0, true);
	if (ptag == NULL)
	{
		DevCon.Warning("Write Fifo to EE: ptag == NULL");
		return false;
	}

	sif0.fifo.read((u32*)ptag, readSize << 2);

	// Clearing handled by vtlb memory protection and manual blocks.
	//Cpu->Clear(sif0ch.madr, readSize*4);

	sif0ch.madr += readSize << 4;
	sif0.ee.cycles += readSize;	// fixme : BIAS is factored in above
	sif0ch.qwc -= readSize;

	if (sif0ch.qwc == 0 && dmacRegs.ctrl.STS == STS_SIF0)
	{
		//DevCon.Warning("SIF0 Stall Control");
		if ((sif0ch.chcr.MOD == NORMAL_MODE) || ((sif0ch.chcr.TAG >> 28) & 0x7) == TAG_CNTS)
			dmacRegs.stadr.ADDR = sif0ch.madr;
	}

	return true;
}

// Write IOP to Fifo.
static __fi bool WriteIOPtoFifo()
{
	// There's some data ready to transfer into the fifo..
	const int writeSize = std::min(sif0.iop.counter, sif0.fifo.sif_free());

	SIF_LOG("Write IOP to Fifo: +++++++++++ %lX of %lX", writeSize, sif0.iop.counter);

	sif0.fifo.write((u32*)iopPhysMem(hw_dma9.madr), writeSize);
	hw_dma9.madr += writeSize << 2;

	// iop is 1/8th the clock rate of the EE and psxcycles is in words (not quadwords).
	sif0.iop.cycles += writeSize; //1 word per cycle
	sif0.iop.counter -= writeSize;


	return true;
}

// Read Fifo into an ee tag, transfer it to sif0ch, and process it.
static __fi bool ProcessEETag()
{
	alignas(16) static u32 tag[4];
	tDMA_TAG& ptag(*(tDMA_TAG*)tag);

	sif0.fifo.read((u32*)&tag[0], 4); // Tag
	SIF_LOG("SIF0 EE read tag: %x %x %x %x", tag[0], tag[1], tag[2], tag[3]);

	sif0ch.unsafeTransfer(&ptag);
	sif0ch.madr = tag[1];

	SIF_LOG("SIF0 EE dest chain tag madr:%08X qwc:%04X id:%X irq:%d(%08X_%08X)",
		sif0ch.madr, sif0ch.qwc, ptag.ID, ptag.IRQ, tag[1], tag[0]);

	if (sif0ch.chcr.TIE && ptag.IRQ)
	{
		//Console.WriteLn("SIF0 TIE");
		sif0.ee.end = true;
	}

	switch (ptag.ID)
	{
		case TAG_CNT:	break;

		case TAG_CNTS:
			if (dmacRegs.ctrl.STS == STS_SIF0) // STS == SIF0 - Initial Value
					dmacRegs.stadr.ADDR = sif0ch.madr;
			break;

		case TAG_END:
			sif0.ee.end = true;
			break;
	}
	return true;
}

// Read Fifo into an iop tag, and transfer it to hw_dma9. And presumably process it.
static __fi bool ProcessIOPTag()
{
	// Process DMA tag at hw_dma9.tadr
	sif0.iop.data = *(sifData *)iopPhysMem(hw_dma9.tadr);
	sif0.iop.data.words = sif0.iop.data.words;

	// send the EE's side of the DMAtag.  The tag is only 64 bits, with the upper 64 bits being the next IOP tag
	// ignored by the EE, however required for alignment and used as junk data in small packets.
	sif0.fifo.write((u32*)iopPhysMem(hw_dma9.tadr + 8), 4);

	// I know we just sent 1QW, because of the size of the EE read, but only 64bits was valid
	// so we advance by 64bits after the EE tag to get the next IOP tag.
	hw_dma9.tadr += 16;

	// We're only copying the first 24 bits.  Bits 30 and 31 (checked below) are Stop/IRQ bits.
	hw_dma9.madr = sif0data & 0xFFFFFF;
	if (sif0words > 0xFFFFF) DevCon.Warning("SIF0 Overrun %x", sif0words);
	//Maximum transfer amount 1mb-16 also masking out top part which is a "Mode" cache stuff, we don't care :)
	sif0.iop.counter = sif0words & 0xFFFFF;

	// Save the number of words we need to write to make up 1QW from this packet. (See "Junk data writing" in Sif.h)
	sif0.iop.writeJunk = (sif0.iop.counter & 0x3) ? (4 - sif0.iop.counter & 0x3) : 0;

	// IOP tags have an IRQ bit and an End of Transfer bit:
	if (sif0tag.IRQ  || (sif0tag.ID & 4)) sif0.iop.end = true;
	SIF_LOG("SIF0 IOP Tag: madr=%lx, tadr=%lx, counter=%lx (%08X_%08X) Junk %d", hw_dma9.madr, hw_dma9.tadr, sif0.iop.counter, sif0words, sif0data, sif0.iop.writeJunk);

	return true;
}

// Stop transferring ee, and signal an interrupt.
static __fi void EndEE()
{
	SIF_LOG("Sif0: End EE");
	sif0.ee.end = false;
	sif0.ee.busy = false;
	if (sif0.ee.cycles == 0)
	{
		SIF_LOG("SIF0 EE: cycles = 0");
		sif0.ee.cycles = 1;
	}
	CPU_SET_DMASTALL(DMAC_SIF0, false);
	CPU_INT(DMAC_SIF0, sif0.ee.cycles*BIAS);
}

// Stop transferring iop, and signal an interrupt.
static __fi void EndIOP()
{
	SIF_LOG("Sif0: End IOP");
	sif0data = 0;
	sif0.iop.end = false;
	sif0.iop.busy = false;

	if (sif0.iop.cycles == 0)
	{
		DevCon.Warning("SIF0 IOP: cycles = 0");
		sif0.iop.cycles = 1;
	}
	// Hack alert
	// Parappa the rapper hates SIF0 taking the length of time it should do on bigger packets
	// I logged it and couldn't work out why, changing any other SIF timing (EE or IOP) seems to have no effect.
	if (sif0.iop.cycles > 1000)
		sif0.iop.cycles >>= 1; //2 word per cycle

	PSX_INT(IopEvt_SIF0, sif0.iop.cycles);
}

// Handle the EE transfer.
static __fi void HandleEETransfer()
{
	if(!sif0ch.chcr.STR)
	{
		//DevCon.Warning("Replacement for irq prevention hack EE SIF0");
		sif0.ee.end = false;
		sif0.ee.busy = false;
		return;
	}

	/*if (sif0ch.qwc == 0)
		if (sif0ch.chcr.MOD == NORMAL_MODE)
			if (!sif0.ee.end){
				DevCon.Warning("sif0 irq prevented");
				done = true;
				return;
			}*/

	if (sif0ch.qwc <= 0)
	{
		if ((sif0ch.chcr.MOD == NORMAL_MODE) || sif0.ee.end)
		{
			// Stop transferring ee, and signal an interrupt.
			done = true;
			EndEE();
		}
		else if (sif0.fifo.size >= 4) // Read a tag
		{
			// Read Fifo into an ee tag, transfer it to sif0ch
			// and process it.
			ProcessEETag();
		}
	}

	if (sif0ch.qwc > 0) // If we're writing something, continue to do so.
	{
		// Write from Fifo to EE.
		if (sif0.fifo.size >= 4)
		{
			WriteFifoToEE();
		}
	}
}

// Handle the IOP transfer.
// Note: Test any changes in this function against Grandia III.
// What currently happens is this:
// SIF0 DMA start...
// SIF + 4 = 4 (pos=4)
// SIF0 IOP Tag: madr=19870, tadr=179cc, counter=8 (00000008_80019870)
// SIF - 4 = 0 (pos=4)
// SIF0 EE read tag: 90000002 935c0 0 0
// SIF0 EE dest chain tag madr:000935C0 qwc:0002 id:1 irq:1(000935C0_90000002)
// Write Fifo to EE: ----------- 0 of 8
// SIF - 0 = 0 (pos=4)
// Write IOP to Fifo: +++++++++++ 8 of 8
// SIF + 8 = 8 (pos=12)
// Write Fifo to EE: ----------- 8 of 8
// SIF - 8 = 0 (pos=12)
// Sif0: End IOP
// Sif0: End EE
// SIF0 DMA end...

// What happens if (sif0.iop.counter > 0) is handled first is this

// SIF0 DMA start...
// ...
// SIF + 8 = 8 (pos=12)
// Sif0: End IOP
// Write Fifo to EE: ----------- 8 of 8
// SIF - 8 = 0 (pos=12)
// SIF0 DMA end...

static __fi void HandleIOPTransfer()
{
	if (sif0.iop.counter <= 0) // If there's no more to transfer
	{
		if (sif0.iop.end)
		{
			// Stop transferring iop, and signal an interrupt.
			done = true;
			EndIOP();
		}
		else
		{
			// Read Fifo into an iop tag, and transfer it to hw_dma9.
			// And presumably process it.
			ProcessIOPTag();
		}
	}
	else
	{
		// Write IOP to Fifo.
		if (sif0.fifo.sif_free() > 0)
		{
			WriteIOPtoFifo();
		}
	}
}

static __fi void Sif0End()
{
	psHu32(SBUS_F240) &= ~0x20;
	psHu32(SBUS_F240) &= ~0x2000;

	DMA_LOG("SIF0 DMA End");
}

// Transfer IOP to EE, putting data in the fifo as an intermediate step.
__fi void SIF0Dma()
{
	int BusyCheck = 0;
	Sif0Init();

	do
	{
		//I realise this is very hacky in a way but its an easy way of checking if both are doing something
		BusyCheck = 0;

		if (sif0.iop.counter == 0 && sif0.iop.writeJunk && sif0.fifo.sif_free() >= sif0.iop.writeJunk)
		{
			SIF_LOG("Writing Junk %d", sif0.iop.writeJunk);
			sif0.fifo.writeJunk(sif0.iop.writeJunk);
			sif0.iop.writeJunk = 0;
		}

		if (sif0.iop.busy)
		{
			if(sif0.fifo.sif_free() > 0 || (sif0.iop.end && sif0.iop.counter == 0))
			{
				BusyCheck++;
				HandleIOPTransfer();
			}
		}
		if (sif0.ee.busy)
		{
			if(sif0.fifo.size >= 4 || (sif0.ee.end && sif0ch.qwc == 0))
			{
				BusyCheck++;
				HandleEETransfer();
			}
		}
	} while (/*!done && */BusyCheck > 0); // Substituting (sif0.ee.busy || sif0.iop.busy) breaks things.

	Sif0End();
}

__fi void  sif0Interrupt()
{
	HW_DMA9_CHCR &= ~0x01000000;
	psxDmaInterrupt2(2);
}

__fi void  EEsif0Interrupt()
{
	hwDmacIrq(DMAC_SIF0);
	sif0ch.chcr.STR = false;
}

__fi void dmaSIF0()
{
	SIF_LOG("dmaSIF0 %s", sif0ch.cmqt_to_str().c_str());

	if (sif0.fifo.readPos != sif0.fifo.writePos)
	{
		SIF_LOG("warning, sif0.fifoReadPos != sif0.fifoWritePos");
	}

	//if(sif0ch.chcr.MOD == CHAIN_MODE && sif0ch.qwc > 0) DevCon.Warning(L"SIF0 QWC on Chain CHCR " + sif0ch.chcr.desc());
	psHu32(SBUS_F240) |= 0x2000;
	sif0.ee.busy = true;

	// Okay, this here is needed currently (r3644).
	// FFX battles in the thunder plains map die otherwise, Phantasy Star 4 as well
	// These 2 games could be made playable again by increasing the time the EE or the IOP run,
	// showing that this is very timing sensible.
	// Doing this DMA unfortunately brings back an old warning in Legend of Legaia though, but it still works.

	//Updated 23/08/2011: The hangs are caused by the EE suspending SIF1 DMA and restarting it when in the middle
	//of processing a "REFE" tag, so the hangs can be solved by forcing the ee.end to be false
	// (as it should always be at the beginning of a DMA).  using "if iop is busy" flags breaks Tom Clancy Rainbow Six.
	// Legend of Legaia doesn't throw a warning either :)
	sif0.ee.end = false;
	CPU_SET_DMASTALL(DMAC_SIF0, false);
	SIF0Dma();

}
