// 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 u8 *videoBuffer;
static Common::Event fifo_exit_event;
// STATE_TO_SAVE
static int size = 0;
}  // namespace

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_exit_event.Init();
	fifoStateRun = false;
}

void Fifo_Shutdown()
{
	if (fifoStateRun)
		PanicAlert("Fifo shutting down while active");
    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()
{
    fifoStateRun = false;

	fifo_exit_event.MsgWait();
	fifo_exit_event.Shutdown();
}

// May be executed from any thread, even the graphics thread.
// Created to allow for self shutdown.
void Fifo_ExitLoopNonBlocking()
{
	fifoStateRun = false;
}

// 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);
}

// Description: Main FIFO update loop
// Purpose: Keep the Core HW updated about the CPU-GPU distance
void Fifo_EnterLoop(const SVideoInitialize &video_initialize)
{
    fifoStateRun = true;
    SCPFifoStruct &_fifo = CommandProcessor::fifo;
	s32 distToSend;

    while (fifoStateRun)
    {
		video_initialize.pPeekMessages();

		VideoFifo_CheckEFBAccess();
		VideoFifo_CheckSwapRequest();

        // check if we are able to run this buffer
		if (_fifo.bFF_GPReadEnable && _fifo.CPReadWriteDistance && !_fifo.bFF_Breakpoint)
		{
			Common::AtomicStore(_fifo.CPReadIdle, 0);

			while (_fifo.bFF_GPReadEnable && _fifo.CPReadWriteDistance)
			{
				if (!fifoStateRun)
					break;

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

				CommandProcessor::FifoCriticalEnter();

// It looks like even in BP mode, we still can send all the chunks we have
/*
				// if we are on BP mode we must send 32B chunks to Video plugin for BP checking
				// TODO (mb2): test & check if MP1/MP2 realy need this now.
				if (_fifo.bFF_BPEnable)
				{
					if (readPtr == _fifo.CPBreakpoint)
					{
						Common::AtomicStore(_fifo.bFF_Breakpoint, 1);
						CommandProcessor::UpdateInterruptsFromVideoPlugin();
						break;
					}

					distToSend = 32;
					
					if ( readPtr >= _fifo.CPEnd) 
						readPtr = _fifo.CPBase;
                    else
                        readPtr += 32;
				}
				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();

				// Those two 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();
			}
			Common::AtomicStore(_fifo.CPReadIdle, 1);
            CommandProcessor::SetFifoIdleFromVideoPlugin();
        }
		else
		{
			Common::YieldCPU();
		}
	}
	fifo_exit_event.Set();
}