// Copyright (C) 2003 Dolphin Project.

// This program 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, version 2.0.

// This program 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 2.0 for more details.

// A copy of the GPL 2.0 should have been included with the program.
// If not, see http://www.gnu.org/licenses/

// Official SVN repository and contact information can be found at
// http://code.google.com/p/dolphin-emu/

#include <string.h>

#include "VideoConfig.h"
#include "Setup.h"
#include "MemoryUtil.h"
#include "Thread.h"
#include "Atomic.h"
#include "OpcodeDecoding.h"
#include "CommandProcessor.h"
#include "ChunkFile.h"
#include "Fifo.h"

volatile bool g_bSkipCurrentFrame = false;
volatile bool g_EFBAccessRequested = false;
extern u8* g_pVideoData;

namespace
{
static volatile bool fifoStateRun = false;
static volatile bool EmuRunning = false;
static u8 *videoBuffer;
static Common::EventEx fifo_run_event;
// STATE_TO_SAVE
static int size = 0;

}  // namespace

Common::Thread *g_hFifoThread = NULL;
SVideoInitialize video_initialize;

void Fifo_DoState(PointerWrap &p) 
{
	CommandProcessor::FifoCriticalEnter();

    p.DoArray(videoBuffer, FIFO_SIZE);
    p.Do(size);
	int pos = (int)(g_pVideoData - videoBuffer); // get offset
	p.Do(pos); // read or write offset (depends on the mode afaik)
	g_pVideoData = &videoBuffer[pos]; // overwrite g_pVideoData -> expected no change when load ss and change when save ss

	CommandProcessor::FifoCriticalLeave();
}

void Fifo_Init()
{
    videoBuffer = (u8*)AllocateMemoryPages(FIFO_SIZE);
	fifo_run_event.Init();
	fifoStateRun = false;
}

void Fifo_Shutdown()
{
	if (fifoStateRun) PanicAlert("Fifo shutting down while active");
	fifo_run_event.Shutdown();
    FreeMemoryPages(videoBuffer, FIFO_SIZE);
}

u8* FAKE_GetFifoStartPtr()
{
    return videoBuffer;
}

u8* FAKE_GetFifoEndPtr()
{
	return &videoBuffer[size];
}

void Fifo_SetRendering(bool enabled)
{
	g_bSkipCurrentFrame = !enabled;
}

// Executed from another thread, no the graphics thread!
// Basically, all it does is set a flag so that the loop will eventually exit, then
// waits for the event to be set, which happens when the loop does exit.
// If we look stuck in here, then the video thread is stuck in something and won't exit
// the loop. Switch to the video thread and investigate.
void Fifo_ExitLoop()
{
	Fifo_ExitLoopNonBlocking();
}

// May be executed from any thread, even the graphics thread.
// Created to allow for self shutdown.
void Fifo_ExitLoopNonBlocking()
{
	// This should break the wait loop in CPU thread
	CommandProcessor::fifo.bFF_GPReadEnable = false;
	CommandProcessor::SetFifoIdleFromVideoPlugin();
	// Terminate GPU thread loop
	fifoStateRun = false;
	fifo_run_event.Set();
}

void Fifo_RunLoop(bool run)
{
	EmuRunning = run;
	if (run)
		fifo_run_event.Set();
}

// Description: Fifo_EnterLoop() sends data through this function.
void Fifo_SendFifoData(u8* _uData, u32 len)
{
    if (size + len >= FIFO_SIZE)
    {
		int pos = (int)(g_pVideoData - videoBuffer);
        if (size - pos > pos)
        {
            PanicAlert("FIFO out of bounds (sz = %i, at %08x)", size, pos);
        }
        memmove(&videoBuffer[0], &videoBuffer[pos], size - pos);
        size -= pos;
		g_pVideoData = videoBuffer;
    }
	// Copy new video instructions to videoBuffer for future use in rendering the new picture
    memcpy(videoBuffer + size, _uData, len);
    size += len;
    OpcodeDecoder_Run(g_bSkipCurrentFrame);
}

inline void Fifo_Run()
{
	SCPFifoStruct &_fifo = CommandProcessor::fifo;
	s32 distToSend;

	// check if we are able to run this buffer
	while (_fifo.bFF_GPReadEnable && ((!_fifo.bFF_BPEnable && _fifo.CPReadWriteDistance) || (_fifo.bFF_BPEnable && !_fifo.bFF_Breakpoint)))
	{
		if (!fifoStateRun)
			break;

		CommandProcessor::FifoCriticalEnter();

		// Create pointer to video data and send it to the VideoPlugin
		u32 readPtr = _fifo.CPReadPointer;			
		u8 *uData = video_initialize.pGetMemoryPointer(readPtr);

		// If we are in BP mode we only send 32B chunks to Video plugin for BP checking
		if (_fifo.bFF_BPEnable)
		{
			// Sometimes we have already exceeded the BP even before it is set
			// so careful check is required
			if (
				(readPtr == _fifo.CPBreakpoint) ||
				//(readPtr <= _fifo.CPBreakpoint && readPtr + 32 > _fifo.CPBreakpoint) ||	
				(readPtr <= _fifo.CPWritePointer && _fifo.CPWritePointer < _fifo.CPBreakpoint) ||
				(readPtr <= _fifo.CPWritePointer && readPtr > _fifo.CPBreakpoint) ||
				(readPtr > _fifo.CPBreakpoint && _fifo.CPBreakpoint > _fifo.CPWritePointer)
				)
			{
				Common::AtomicStore(_fifo.bFF_Breakpoint, 1);
				CommandProcessor::UpdateInterruptsFromVideoPlugin(true);
				CommandProcessor::FifoCriticalLeave();
				break;
			}
			distToSend = 32;

			if ( readPtr >= _fifo.CPEnd) 
				readPtr = _fifo.CPBase;
			else
				readPtr += 32;
		}
		// If we are not in BP mode we send all the chunk we have to speed up
		else
		{
			distToSend = _fifo.CPReadWriteDistance;
			// send 1024B chunk max length to have better control over PeekMessages' period
			distToSend = distToSend > 1024 ? 1024 : distToSend;
			// add 32 bytes because the cp end points to the start of the last 32 byte chunk
			if ((distToSend + readPtr) >= (_fifo.CPEnd + 32)) // TODO: better?
			{
				distToSend =(_fifo.CPEnd + 32) - readPtr;
				readPtr = _fifo.CPBase;
			}
			else
				readPtr += distToSend;
		}

		// Execute new instructions found in uData
		Fifo_SendFifoData(uData, distToSend);

		Common::AtomicStore(_fifo.CPReadPointer, readPtr);
		Common::AtomicAdd(_fifo.CPReadWriteDistance, -distToSend);

		CommandProcessor::FifoCriticalLeave();
	}

	CommandProcessor::SetFifoIdleFromVideoPlugin();
}

// Regular thread
THREAD_RETURN fifo_thread(void* lpParameter)
{
	while (fifoStateRun)
	{
		Fifo_Run();

		// Must use YieldCPU() in this loop.  SLEEP(1) will make MP2
		// hang on boot.
		if (EmuRunning)
			Common::YieldCPU();
		else
			fifo_run_event.MsgWait();
	}

	return 0;
}

// Description: Main FIFO update loop
// Purpose: Keep the Core HW updated about the CPU-GPU distance
void Fifo_EnterLoop(const SVideoInitialize &video_init)
{
	fifoStateRun = true;
	video_initialize = video_init;
	
	if (g_ActiveConfig.bUseFIFOThread) // threaded mode
	{
		g_hFifoThread = new Common::Thread(fifo_thread, NULL);
		while (fifoStateRun)
		{
			video_initialize.pPeekMessages();

			// The two VideoFifo checks below are pretty important and must be
			// called in the FIFO Loop. If we don't, s_swapRequested (OGL only)
			// or s_efbAccessRequested won't be set to false leading the CPU
			// thread to wait in Video_BeginField or Video_AccessEFB thus slowing
			// things down.

			VideoFifo_CheckEFBAccess();
			VideoFifo_CheckSwapRequest();
			
			SLEEP(1);
		}
	}
	else
	{
		while (fifoStateRun)
		{
			video_initialize.pPeekMessages();
			VideoFifo_CheckEFBAccess();
			VideoFifo_CheckSwapRequest();

			Fifo_Run();

			if (EmuRunning)
				Common::YieldCPU();
			else
				fifo_run_event.MsgWait();
		}
	}
}