using Ryujinx.Common;
using Ryujinx.Graphics.Gal;
using Ryujinx.Graphics.Memory;
using Ryujinx.Graphics.Texture;
using System;
using System.Collections.Generic;

namespace Ryujinx.Graphics
{
    public class NvGpuEngine3d : INvGpuEngine
    {
        public int[] Registers { get; private set; }

        private NvGpu Gpu;

        private Dictionary<int, NvGpuMethod> Methods;

        private struct ConstBuffer
        {
            public bool Enabled;
            public long Position;
            public int  Size;
        }

        private ConstBuffer[][] ConstBuffers;

        private List<long>[] UploadedKeys;

        private int CurrentInstance = 0;

        public NvGpuEngine3d(NvGpu Gpu)
        {
            this.Gpu = Gpu;

            Registers = new int[0xe00];

            Methods = new Dictionary<int, NvGpuMethod>();

            void AddMethod(int Meth, int Count, int Stride, NvGpuMethod Method)
            {
                while (Count-- > 0)
                {
                    Methods.Add(Meth, Method);

                    Meth += Stride;
                }
            }

            AddMethod(0x585,  1, 1, VertexEndGl);
            AddMethod(0x674,  1, 1, ClearBuffers);
            AddMethod(0x6c3,  1, 1, QueryControl);
            AddMethod(0x8e4, 16, 1, CbData);
            AddMethod(0x904,  5, 8, CbBind);

            ConstBuffers = new ConstBuffer[6][];

            for (int Index = 0; Index < ConstBuffers.Length; Index++)
            {
                ConstBuffers[Index] = new ConstBuffer[18];
            }

            UploadedKeys = new List<long>[(int)NvGpuBufferType.Count];

            for (int i = 0; i < UploadedKeys.Length; i++)
            {
                UploadedKeys[i] = new List<long>();
            }

            //Ensure that all components are enabled by default.
            //FIXME: Is this correct?
            WriteRegister(NvGpuEngine3dReg.ColorMaskN, 0x1111);
        }

        public void CallMethod(NvGpuVmm Vmm, NvGpuPBEntry PBEntry)
        {
            if (Methods.TryGetValue(PBEntry.Method, out NvGpuMethod Method))
            {
                Method(Vmm, PBEntry);
            }
            else
            {
                WriteRegister(PBEntry);
            }
        }

        public void ResetCache()
        {
            foreach (List<long> Uploaded in UploadedKeys)
            {
                Uploaded.Clear();
            }
        }

        private void VertexEndGl(NvGpuVmm Vmm, NvGpuPBEntry PBEntry)
        {
            LockCaches();

            GalPipelineState State = new GalPipelineState();

            SetFrameBuffer(State);
            SetFrontFace(State);
            SetCullFace(State);
            SetDepth(State);
            SetStencil(State);
            SetBlending(State);
            SetColorMask(State);
            SetPrimitiveRestart(State);

            for (int FbIndex = 0; FbIndex < 8; FbIndex++)
            {
                SetFrameBuffer(Vmm, FbIndex);
            }

            SetZeta(Vmm);

            SetRenderTargets();

            long[] Keys = UploadShaders(Vmm);

            Gpu.Renderer.Shader.BindProgram();

            UploadTextures(Vmm, State, Keys);
            UploadConstBuffers(Vmm, State, Keys);
            UploadVertexArrays(Vmm, State);

            DispatchRender(Vmm, State);

            UnlockCaches();
        }

        private void LockCaches()
        {
            Gpu.Renderer.Buffer.LockCache();
            Gpu.Renderer.Rasterizer.LockCaches();
            Gpu.Renderer.Texture.LockCache();
        }

        private void UnlockCaches()
        {
            Gpu.Renderer.Buffer.UnlockCache();
            Gpu.Renderer.Rasterizer.UnlockCaches();
            Gpu.Renderer.Texture.UnlockCache();
        }

        private void ClearBuffers(NvGpuVmm Vmm, NvGpuPBEntry PBEntry)
        {
            int Arg0 = PBEntry.Arguments[0];

            int Attachment = (Arg0 >> 6) & 0xf;

            GalClearBufferFlags Flags = (GalClearBufferFlags)(Arg0 & 0x3f);

            float Red   = ReadRegisterFloat(NvGpuEngine3dReg.ClearNColor + 0);
            float Green = ReadRegisterFloat(NvGpuEngine3dReg.ClearNColor + 1);
            float Blue  = ReadRegisterFloat(NvGpuEngine3dReg.ClearNColor + 2);
            float Alpha = ReadRegisterFloat(NvGpuEngine3dReg.ClearNColor + 3);

            float Depth = ReadRegisterFloat(NvGpuEngine3dReg.ClearDepth);

            int Stencil = ReadRegister(NvGpuEngine3dReg.ClearStencil);

            SetFrameBuffer(Vmm, Attachment);

            SetZeta(Vmm);

            SetRenderTargets();

            Gpu.Renderer.RenderTarget.Bind();

            Gpu.Renderer.Rasterizer.ClearBuffers(Flags, Attachment, Red, Green, Blue, Alpha, Depth, Stencil);

            Gpu.Renderer.Pipeline.ResetDepthMask();
            Gpu.Renderer.Pipeline.ResetColorMask(Attachment);
        }

        private void SetFrameBuffer(NvGpuVmm Vmm, int FbIndex)
        {
            long VA = MakeInt64From2xInt32(NvGpuEngine3dReg.FrameBufferNAddress + FbIndex * 0x10);

            int SurfFormat = ReadRegister(NvGpuEngine3dReg.FrameBufferNFormat + FbIndex * 0x10);

            if (VA == 0 || SurfFormat == 0)
            {
                Gpu.Renderer.RenderTarget.UnbindColor(FbIndex);

                return;
            }

            long Key = Vmm.GetPhysicalAddress(VA);

            int Width  = ReadRegister(NvGpuEngine3dReg.FrameBufferNWidth  + FbIndex * 0x10);
            int Height = ReadRegister(NvGpuEngine3dReg.FrameBufferNHeight + FbIndex * 0x10);

            int BlockDim = ReadRegister(NvGpuEngine3dReg.FrameBufferNBlockDim + FbIndex * 0x10);

            int GobBlockHeight = 1 << ((BlockDim >> 4) & 7);

            GalMemoryLayout Layout = (GalMemoryLayout)((BlockDim >> 12) & 1);

            float TX = ReadRegisterFloat(NvGpuEngine3dReg.ViewportNTranslateX + FbIndex * 8);
            float TY = ReadRegisterFloat(NvGpuEngine3dReg.ViewportNTranslateY + FbIndex * 8);

            float SX = ReadRegisterFloat(NvGpuEngine3dReg.ViewportNScaleX + FbIndex * 8);
            float SY = ReadRegisterFloat(NvGpuEngine3dReg.ViewportNScaleY + FbIndex * 8);

            int VpX = (int)MathF.Max(0, TX - MathF.Abs(SX));
            int VpY = (int)MathF.Max(0, TY - MathF.Abs(SY));

            int VpW = (int)(TX + MathF.Abs(SX)) - VpX;
            int VpH = (int)(TY + MathF.Abs(SY)) - VpY;

            GalImageFormat Format = ImageUtils.ConvertSurface((GalSurfaceFormat)SurfFormat);

            GalImage Image = new GalImage(Width, Height, 1, GobBlockHeight, Layout, Format);

            Gpu.ResourceManager.SendColorBuffer(Vmm, Key, FbIndex, Image);

            Gpu.Renderer.RenderTarget.SetViewport(FbIndex, VpX, VpY, VpW, VpH);
        }

        private void SetFrameBuffer(GalPipelineState State)
        {
            State.FramebufferSrgb = ReadRegisterBool(NvGpuEngine3dReg.FrameBufferSrgb);

            State.FlipX = GetFlipSign(NvGpuEngine3dReg.ViewportNScaleX);
            State.FlipY = GetFlipSign(NvGpuEngine3dReg.ViewportNScaleY);
        }

        private void SetZeta(NvGpuVmm Vmm)
        {
            long VA = MakeInt64From2xInt32(NvGpuEngine3dReg.ZetaAddress);

            int ZetaFormat = ReadRegister(NvGpuEngine3dReg.ZetaFormat);

            int BlockDim = ReadRegister(NvGpuEngine3dReg.ZetaBlockDimensions);

            int GobBlockHeight = 1 << ((BlockDim >> 4) & 7);

            GalMemoryLayout Layout = (GalMemoryLayout)((BlockDim >> 12) & 1); //?

            bool ZetaEnable = ReadRegisterBool(NvGpuEngine3dReg.ZetaEnable);

            if (VA == 0 || ZetaFormat == 0 || !ZetaEnable)
            {
                Gpu.Renderer.RenderTarget.UnbindZeta();

                return;
            }

            long Key = Vmm.GetPhysicalAddress(VA);

            int Width  = ReadRegister(NvGpuEngine3dReg.ZetaHoriz);
            int Height = ReadRegister(NvGpuEngine3dReg.ZetaVert);

            GalImageFormat Format = ImageUtils.ConvertZeta((GalZetaFormat)ZetaFormat);

            GalImage Image = new GalImage(Width, Height, 1, GobBlockHeight, Layout, Format);

            Gpu.ResourceManager.SendZetaBuffer(Vmm, Key, Image);
        }

        private long[] UploadShaders(NvGpuVmm Vmm)
        {
            long[] Keys = new long[5];

            long BasePosition = MakeInt64From2xInt32(NvGpuEngine3dReg.ShaderAddress);

            int Index = 1;

            int VpAControl = ReadRegister(NvGpuEngine3dReg.ShaderNControl);

            bool VpAEnable = (VpAControl & 1) != 0;

            if (VpAEnable)
            {
                //Note: The maxwell supports 2 vertex programs, usually
                //only VP B is used, but in some cases VP A is also used.
                //In this case, it seems to function as an extra vertex
                //shader stage.
                //The graphics abstraction layer has a special overload for this
                //case, which should merge the two shaders into one vertex shader.
                int VpAOffset = ReadRegister(NvGpuEngine3dReg.ShaderNOffset);
                int VpBOffset = ReadRegister(NvGpuEngine3dReg.ShaderNOffset + 0x10);

                long VpAPos = BasePosition + (uint)VpAOffset;
                long VpBPos = BasePosition + (uint)VpBOffset;

                Keys[(int)GalShaderType.Vertex] = VpBPos;

                Gpu.Renderer.Shader.Create(Vmm, VpAPos, VpBPos, GalShaderType.Vertex);
                Gpu.Renderer.Shader.Bind(VpBPos);

                Index = 2;
            }

            for (; Index < 6; Index++)
            {
                GalShaderType Type = GetTypeFromProgram(Index);

                int Control = ReadRegister(NvGpuEngine3dReg.ShaderNControl + Index * 0x10);
                int Offset  = ReadRegister(NvGpuEngine3dReg.ShaderNOffset  + Index * 0x10);

                //Note: Vertex Program (B) is always enabled.
                bool Enable = (Control & 1) != 0 || Index == 1;

                if (!Enable)
                {
                    Gpu.Renderer.Shader.Unbind(Type);

                    continue;
                }

                long Key = BasePosition + (uint)Offset;

                Keys[(int)Type] = Key;

                Gpu.Renderer.Shader.Create(Vmm, Key, Type);
                Gpu.Renderer.Shader.Bind(Key);
            }

            return Keys;
        }

        private static GalShaderType GetTypeFromProgram(int Program)
        {
            switch (Program)
            {
                case 0:
                case 1: return GalShaderType.Vertex;
                case 2: return GalShaderType.TessControl;
                case 3: return GalShaderType.TessEvaluation;
                case 4: return GalShaderType.Geometry;
                case 5: return GalShaderType.Fragment;
            }

            throw new ArgumentOutOfRangeException(nameof(Program));
        }

        private void SetFrontFace(GalPipelineState State)
        {
            float SignX = GetFlipSign(NvGpuEngine3dReg.ViewportNScaleX);
            float SignY = GetFlipSign(NvGpuEngine3dReg.ViewportNScaleY);

            GalFrontFace FrontFace = (GalFrontFace)ReadRegister(NvGpuEngine3dReg.FrontFace);

            //Flipping breaks facing. Flipping front facing too fixes it
            if (SignX != SignY)
            {
                switch (FrontFace)
                {
                    case GalFrontFace.CW:  FrontFace = GalFrontFace.CCW; break;
                    case GalFrontFace.CCW: FrontFace = GalFrontFace.CW;  break;
                }
            }

            State.FrontFace = FrontFace;
        }

        private void SetCullFace(GalPipelineState State)
        {
            State.CullFaceEnabled = ReadRegisterBool(NvGpuEngine3dReg.CullFaceEnable);

            if (State.CullFaceEnabled)
            {
                State.CullFace = (GalCullFace)ReadRegister(NvGpuEngine3dReg.CullFace);
            }
        }

        private void SetDepth(GalPipelineState State)
        {
            State.DepthTestEnabled = ReadRegisterBool(NvGpuEngine3dReg.DepthTestEnable);

            State.DepthWriteEnabled = ReadRegisterBool(NvGpuEngine3dReg.DepthWriteEnable);

            if (State.DepthTestEnabled)
            {
                State.DepthFunc = (GalComparisonOp)ReadRegister(NvGpuEngine3dReg.DepthTestFunction);
            }

            State.DepthRangeNear = ReadRegisterFloat(NvGpuEngine3dReg.DepthRangeNNear);
            State.DepthRangeFar  = ReadRegisterFloat(NvGpuEngine3dReg.DepthRangeNFar);
        }

        private void SetStencil(GalPipelineState State)
        {
            State.StencilTestEnabled = ReadRegisterBool(NvGpuEngine3dReg.StencilEnable);

            if (State.StencilTestEnabled)
            {
                State.StencilBackFuncFunc = (GalComparisonOp)ReadRegister(NvGpuEngine3dReg.StencilBackFuncFunc);
                State.StencilBackFuncRef  =                  ReadRegister(NvGpuEngine3dReg.StencilBackFuncRef);
                State.StencilBackFuncMask =            (uint)ReadRegister(NvGpuEngine3dReg.StencilBackFuncMask);
                State.StencilBackOpFail   =    (GalStencilOp)ReadRegister(NvGpuEngine3dReg.StencilBackOpFail);
                State.StencilBackOpZFail  =    (GalStencilOp)ReadRegister(NvGpuEngine3dReg.StencilBackOpZFail);
                State.StencilBackOpZPass  =    (GalStencilOp)ReadRegister(NvGpuEngine3dReg.StencilBackOpZPass);
                State.StencilBackMask     =            (uint)ReadRegister(NvGpuEngine3dReg.StencilBackMask);

                State.StencilFrontFuncFunc = (GalComparisonOp)ReadRegister(NvGpuEngine3dReg.StencilFrontFuncFunc);
                State.StencilFrontFuncRef  =                  ReadRegister(NvGpuEngine3dReg.StencilFrontFuncRef);
                State.StencilFrontFuncMask =            (uint)ReadRegister(NvGpuEngine3dReg.StencilFrontFuncMask);
                State.StencilFrontOpFail   =    (GalStencilOp)ReadRegister(NvGpuEngine3dReg.StencilFrontOpFail);
                State.StencilFrontOpZFail  =    (GalStencilOp)ReadRegister(NvGpuEngine3dReg.StencilFrontOpZFail);
                State.StencilFrontOpZPass  =    (GalStencilOp)ReadRegister(NvGpuEngine3dReg.StencilFrontOpZPass);
                State.StencilFrontMask     =            (uint)ReadRegister(NvGpuEngine3dReg.StencilFrontMask);
            }
        }

        private void SetBlending(GalPipelineState State)
        {
            //TODO: Support independent blend properly.
            State.BlendEnabled = ReadRegisterBool(NvGpuEngine3dReg.IBlendNEnable);

            if (State.BlendEnabled)
            {
                State.BlendSeparateAlpha = ReadRegisterBool(NvGpuEngine3dReg.IBlendNSeparateAlpha);

                State.BlendEquationRgb   = (GalBlendEquation)ReadRegister(NvGpuEngine3dReg.IBlendNEquationRgb);
                State.BlendFuncSrcRgb    =   (GalBlendFactor)ReadRegister(NvGpuEngine3dReg.IBlendNFuncSrcRgb);
                State.BlendFuncDstRgb    =   (GalBlendFactor)ReadRegister(NvGpuEngine3dReg.IBlendNFuncDstRgb);
                State.BlendEquationAlpha = (GalBlendEquation)ReadRegister(NvGpuEngine3dReg.IBlendNEquationAlpha);
                State.BlendFuncSrcAlpha  =   (GalBlendFactor)ReadRegister(NvGpuEngine3dReg.IBlendNFuncSrcAlpha);
                State.BlendFuncDstAlpha  =   (GalBlendFactor)ReadRegister(NvGpuEngine3dReg.IBlendNFuncDstAlpha);
            }
        }

        private void SetColorMask(GalPipelineState State)
        {
            bool ColorMaskCommon = ReadRegisterBool(NvGpuEngine3dReg.ColorMaskCommon);

            State.ColorMaskCommon = ColorMaskCommon;

            for (int Index = 0; Index < GalPipelineState.RenderTargetsCount; Index++)
            {
                int ColorMask = ReadRegister(NvGpuEngine3dReg.ColorMaskN + (ColorMaskCommon ? 0 : Index));

                State.ColorMasks[Index].Red   = ((ColorMask >> 0)  & 0xf) != 0;
                State.ColorMasks[Index].Green = ((ColorMask >> 4)  & 0xf) != 0;
                State.ColorMasks[Index].Blue  = ((ColorMask >> 8)  & 0xf) != 0;
                State.ColorMasks[Index].Alpha = ((ColorMask >> 12) & 0xf) != 0;
            }
        }

        private void SetPrimitiveRestart(GalPipelineState State)
        {
            State.PrimitiveRestartEnabled = ReadRegisterBool(NvGpuEngine3dReg.PrimRestartEnable);

            if (State.PrimitiveRestartEnabled)
            {
                State.PrimitiveRestartIndex = (uint)ReadRegister(NvGpuEngine3dReg.PrimRestartIndex);
            }
        }

        private void SetRenderTargets()
        {
            //Commercial games do not seem to
            //bool SeparateFragData = ReadRegisterBool(NvGpuEngine3dReg.RTSeparateFragData);

            uint Control = (uint)(ReadRegister(NvGpuEngine3dReg.RTControl));

            uint Count = Control & 0xf;

            if (Count > 0)
            {
                int[] Map = new int[Count];

                for (int Index = 0; Index < Count; Index++)
                {
                    int Shift = 4 + Index * 3;

                    Map[Index] = (int)((Control >> Shift) & 7);
                }

                Gpu.Renderer.RenderTarget.SetMap(Map);
            }
            else
            {
                Gpu.Renderer.RenderTarget.SetMap(null);
            }
        }

        private void UploadTextures(NvGpuVmm Vmm, GalPipelineState State, long[] Keys)
        {
            long BaseShPosition = MakeInt64From2xInt32(NvGpuEngine3dReg.ShaderAddress);

            int TextureCbIndex = ReadRegister(NvGpuEngine3dReg.TextureCbIndex);

            int TexIndex = 0;

            for (int Index = 0; Index < Keys.Length; Index++)
            {
                foreach (ShaderDeclInfo DeclInfo in Gpu.Renderer.Shader.GetTextureUsage(Keys[Index]))
                {
                    long Position;

                    if (DeclInfo.IsCb)
                    {
                        Position = ConstBuffers[Index][DeclInfo.Cbuf].Position;
                    }
                    else
                    {
                        Position = ConstBuffers[Index][TextureCbIndex].Position;
                    }

                    int TextureHandle = Vmm.ReadInt32(Position + DeclInfo.Index * 4);

                    UploadTexture(Vmm, TexIndex, TextureHandle);

                    TexIndex++;
                }
            }
        }

        private void UploadTexture(NvGpuVmm Vmm, int TexIndex, int TextureHandle)
        {
            if (TextureHandle == 0)
            {
                //TODO: Is this correct?
                //Some games like puyo puyo will have 0 handles.
                //It may be just normal behaviour or a bug caused by sync issues.
                //The game does initialize the value properly after through.
                return;
            }

            int TicIndex = (TextureHandle >>  0) & 0xfffff;
            int TscIndex = (TextureHandle >> 20) & 0xfff;

            long TicPosition = MakeInt64From2xInt32(NvGpuEngine3dReg.TexHeaderPoolOffset);
            long TscPosition = MakeInt64From2xInt32(NvGpuEngine3dReg.TexSamplerPoolOffset);

            TicPosition += TicIndex * 0x20;
            TscPosition += TscIndex * 0x20;

            GalImage Image = TextureFactory.MakeTexture(Vmm, TicPosition);

            GalTextureSampler Sampler = TextureFactory.MakeSampler(Gpu, Vmm, TscPosition);

            long Key = Vmm.ReadInt64(TicPosition + 4) & 0xffffffffffff;

            if (Image.Layout == GalMemoryLayout.BlockLinear)
            {
                Key &= ~0x1ffL;
            }
            else if (Image.Layout == GalMemoryLayout.Pitch)
            {
                Key &= ~0x1fL;
            }

            Key = Vmm.GetPhysicalAddress(Key);

            if (Key == -1)
            {
                //FIXME: Shouldn't ignore invalid addresses.
                return;
            }

            Gpu.ResourceManager.SendTexture(Vmm, Key, Image, TexIndex);

            Gpu.Renderer.Texture.SetSampler(Sampler);
        }

        private void UploadConstBuffers(NvGpuVmm Vmm, GalPipelineState State, long[] Keys)
        {
            for (int Stage = 0; Stage < Keys.Length; Stage++)
            {
                foreach (ShaderDeclInfo DeclInfo in Gpu.Renderer.Shader.GetConstBufferUsage(Keys[Stage]))
                {
                    ConstBuffer Cb = ConstBuffers[Stage][DeclInfo.Cbuf];

                    if (!Cb.Enabled)
                    {
                        continue;
                    }

                    long Key = Vmm.GetPhysicalAddress(Cb.Position);

                    if (QueryKeyUpload(Vmm, Key, Cb.Size, NvGpuBufferType.ConstBuffer))
                    {
                        IntPtr Source = Vmm.GetHostAddress(Cb.Position, Cb.Size);

                        Gpu.Renderer.Buffer.SetData(Key, Cb.Size, Source);
                    }

                    State.ConstBufferKeys[Stage][DeclInfo.Cbuf] = Key;
                }
            }
        }

        private void UploadVertexArrays(NvGpuVmm Vmm, GalPipelineState State)
        {
            long IbPosition = MakeInt64From2xInt32(NvGpuEngine3dReg.IndexArrayAddress);

            long IboKey = Vmm.GetPhysicalAddress(IbPosition);

            int IndexEntryFmt = ReadRegister(NvGpuEngine3dReg.IndexArrayFormat);
            int IndexCount    = ReadRegister(NvGpuEngine3dReg.IndexBatchCount);
            int PrimCtrl      = ReadRegister(NvGpuEngine3dReg.VertexBeginGl);

            GalPrimitiveType PrimType = (GalPrimitiveType)(PrimCtrl & 0xffff);

            GalIndexFormat IndexFormat = (GalIndexFormat)IndexEntryFmt;

            int IndexEntrySize = 1 << IndexEntryFmt;

            if (IndexEntrySize > 4)
            {
                throw new InvalidOperationException();
            }

            if (IndexCount != 0)
            {
                int IbSize = IndexCount * IndexEntrySize;

                bool IboCached = Gpu.Renderer.Rasterizer.IsIboCached(IboKey, (uint)IbSize);

                bool UsesLegacyQuads =
                    PrimType == GalPrimitiveType.Quads ||
                    PrimType == GalPrimitiveType.QuadStrip;

                if (!IboCached || QueryKeyUpload(Vmm, IboKey, (uint)IbSize, NvGpuBufferType.Index))
                {
                    if (!UsesLegacyQuads)
                    {
                        IntPtr DataAddress = Vmm.GetHostAddress(IbPosition, IbSize);

                        Gpu.Renderer.Rasterizer.CreateIbo(IboKey, IbSize, DataAddress);
                    }
                    else
                    {
                        byte[] Buffer = Vmm.ReadBytes(IbPosition, IbSize);

                        if (PrimType == GalPrimitiveType.Quads)
                        {
                            Buffer = QuadHelper.ConvertIbQuadsToTris(Buffer, IndexEntrySize, IndexCount);
                        }
                        else /* if (PrimType == GalPrimitiveType.QuadStrip) */
                        {
                            Buffer = QuadHelper.ConvertIbQuadStripToTris(Buffer, IndexEntrySize, IndexCount);
                        }

                        Gpu.Renderer.Rasterizer.CreateIbo(IboKey, IbSize, Buffer);
                    }
                }

                if (!UsesLegacyQuads)
                {
                    Gpu.Renderer.Rasterizer.SetIndexArray(IbSize, IndexFormat);
                }
                else
                {
                    if (PrimType == GalPrimitiveType.Quads)
                    {
                        Gpu.Renderer.Rasterizer.SetIndexArray(QuadHelper.ConvertIbSizeQuadsToTris(IbSize), IndexFormat);
                    }
                    else /* if (PrimType == GalPrimitiveType.QuadStrip) */
                    {
                        Gpu.Renderer.Rasterizer.SetIndexArray(QuadHelper.ConvertIbSizeQuadStripToTris(IbSize), IndexFormat);
                    }
                }
            }

            List<GalVertexAttrib>[] Attribs = new List<GalVertexAttrib>[32];

            for (int Attr = 0; Attr < 16; Attr++)
            {
                int Packed = ReadRegister(NvGpuEngine3dReg.VertexAttribNFormat + Attr);

                int ArrayIndex = Packed & 0x1f;

                if (Attribs[ArrayIndex] == null)
                {
                    Attribs[ArrayIndex] = new List<GalVertexAttrib>();
                }

                long VertexPosition = MakeInt64From2xInt32(NvGpuEngine3dReg.VertexArrayNAddress + ArrayIndex * 4);

                int Offset = (Packed >> 7) & 0x3fff;

                //Note: 16 is the maximum size of an attribute,
                //having a component size of 32-bits with 4 elements (a vec4).
                IntPtr Pointer = Vmm.GetHostAddress(VertexPosition + Offset, 16);

                Attribs[ArrayIndex].Add(new GalVertexAttrib(
                                           Attr,
                                         ((Packed >>  6) & 0x1) != 0,
                                           Offset,
                                           Pointer,
                    (GalVertexAttribSize)((Packed >> 21) & 0x3f),
                    (GalVertexAttribType)((Packed >> 27) & 0x7),
                                         ((Packed >> 31) & 0x1) != 0));
            }

            State.VertexBindings = new GalVertexBinding[32];

            for (int Index = 0; Index < 32; Index++)
            {
                if (Attribs[Index] == null)
                {
                    continue;
                }

                int Control = ReadRegister(NvGpuEngine3dReg.VertexArrayNControl + Index * 4);

                bool Enable = (Control & 0x1000) != 0;

                if (!Enable)
                {
                    continue;
                }

                long VertexPosition = MakeInt64From2xInt32(NvGpuEngine3dReg.VertexArrayNAddress + Index * 4);
                long VertexEndPos   = MakeInt64From2xInt32(NvGpuEngine3dReg.VertexArrayNEndAddr + Index * 2);

                int VertexDivisor = ReadRegister(NvGpuEngine3dReg.VertexArrayNDivisor + Index * 4);

                bool Instanced = ReadRegisterBool(NvGpuEngine3dReg.VertexArrayNInstance + Index);

                int Stride = Control & 0xfff;

                if (Instanced && VertexDivisor != 0)
                {
                    VertexPosition += Stride * (CurrentInstance / VertexDivisor);
                }

                if (VertexPosition > VertexEndPos)
                {
                    //Instance is invalid, ignore the draw call
                    continue;
                }

                long VboKey = Vmm.GetPhysicalAddress(VertexPosition);

                long VbSize = (VertexEndPos - VertexPosition) + 1;

                bool VboCached = Gpu.Renderer.Rasterizer.IsVboCached(VboKey, VbSize);

                if (!VboCached || QueryKeyUpload(Vmm, VboKey, VbSize, NvGpuBufferType.Vertex))
                {
                    IntPtr DataAddress = Vmm.GetHostAddress(VertexPosition, VbSize);

                    Gpu.Renderer.Rasterizer.CreateVbo(VboKey, (int)VbSize, DataAddress);
                }

                State.VertexBindings[Index].Enabled   = true;
                State.VertexBindings[Index].Stride    = Stride;
                State.VertexBindings[Index].VboKey    = VboKey;
                State.VertexBindings[Index].Instanced = Instanced;
                State.VertexBindings[Index].Divisor   = VertexDivisor;
                State.VertexBindings[Index].Attribs   = Attribs[Index].ToArray();
            }
        }

        private void DispatchRender(NvGpuVmm Vmm, GalPipelineState State)
        {
            int IndexCount = ReadRegister(NvGpuEngine3dReg.IndexBatchCount);
            int PrimCtrl   = ReadRegister(NvGpuEngine3dReg.VertexBeginGl);

            GalPrimitiveType PrimType = (GalPrimitiveType)(PrimCtrl & 0xffff);

            bool InstanceNext = ((PrimCtrl >> 26) & 1) != 0;
            bool InstanceCont = ((PrimCtrl >> 27) & 1) != 0;

            if (InstanceNext && InstanceCont)
            {
                throw new InvalidOperationException("GPU tried to increase and reset instance count at the same time");
            }

            if (InstanceNext)
            {
                CurrentInstance++;
            }
            else if (!InstanceCont)
            {
                CurrentInstance = 0;
            }

            State.Instance = CurrentInstance;

            Gpu.Renderer.Pipeline.Bind(State);

            Gpu.Renderer.RenderTarget.Bind();

            if (IndexCount != 0)
            {
                int IndexEntryFmt = ReadRegister(NvGpuEngine3dReg.IndexArrayFormat);
                int IndexFirst    = ReadRegister(NvGpuEngine3dReg.IndexBatchFirst);
                int VertexBase    = ReadRegister(NvGpuEngine3dReg.VertexArrayElemBase);

                long IndexPosition = MakeInt64From2xInt32(NvGpuEngine3dReg.IndexArrayAddress);

                long IboKey = Vmm.GetPhysicalAddress(IndexPosition);

                //Quad primitive types were deprecated on OpenGL 3.x,
                //they are converted to a triangles index buffer on IB creation,
                //so we should use the triangles type here too.
                if (PrimType == GalPrimitiveType.Quads ||
                    PrimType == GalPrimitiveType.QuadStrip)
                {
                    PrimType = GalPrimitiveType.Triangles;

                    //Note: We assume that index first points to the first
                    //vertex of a quad, if it points to the middle of a
                    //quad (First % 4 != 0 for Quads) then it will not work properly.
                    if (PrimType == GalPrimitiveType.Quads)
                    {
                        IndexFirst = QuadHelper.ConvertIbSizeQuadsToTris(IndexFirst);
                    }
                    else /* if (PrimType == GalPrimitiveType.QuadStrip) */
                    {
                        IndexFirst = QuadHelper.ConvertIbSizeQuadStripToTris(IndexFirst);
                    }
                }

                Gpu.Renderer.Rasterizer.DrawElements(IboKey, IndexFirst, VertexBase, PrimType);
            }
            else
            {
                int VertexFirst = ReadRegister(NvGpuEngine3dReg.VertexArrayFirst);
                int VertexCount = ReadRegister(NvGpuEngine3dReg.VertexArrayCount);

                Gpu.Renderer.Rasterizer.DrawArrays(VertexFirst, VertexCount, PrimType);
            }

            //Is the GPU really clearing those registers after draw?
            WriteRegister(NvGpuEngine3dReg.IndexBatchFirst, 0);
            WriteRegister(NvGpuEngine3dReg.IndexBatchCount, 0);
        }

        private enum QueryMode
        {
            WriteSeq,
            Sync,
            WriteCounterAndTimestamp
        }

        private void QueryControl(NvGpuVmm Vmm, NvGpuPBEntry PBEntry)
        {
            WriteRegister(PBEntry);

            long Position = MakeInt64From2xInt32(NvGpuEngine3dReg.QueryAddress);

            int Seq  = Registers[(int)NvGpuEngine3dReg.QuerySequence];
            int Ctrl = Registers[(int)NvGpuEngine3dReg.QueryControl];

            QueryMode Mode = (QueryMode)(Ctrl & 3);

            switch (Mode)
            {
                case QueryMode.WriteSeq: Vmm.WriteInt32(Position, Seq); break;

                case QueryMode.WriteCounterAndTimestamp:
                {
                    //TODO: Implement counters.
                    long Counter = 1;

                    long Timestamp = PerformanceCounter.ElapsedMilliseconds;

                    Timestamp = (long)(Timestamp * 615384.615385);

                    Vmm.WriteInt64(Position + 0, Counter);
                    Vmm.WriteInt64(Position + 8, Timestamp);

                    break;
                }
            }
        }

        private void CbData(NvGpuVmm Vmm, NvGpuPBEntry PBEntry)
        {
            long Position = MakeInt64From2xInt32(NvGpuEngine3dReg.ConstBufferAddress);

            int Offset = ReadRegister(NvGpuEngine3dReg.ConstBufferOffset);

            foreach (int Arg in PBEntry.Arguments)
            {
                Vmm.WriteInt32(Position + Offset, Arg);

                Offset += 4;
            }

            WriteRegister(NvGpuEngine3dReg.ConstBufferOffset, Offset);

            UploadedKeys[(int)NvGpuBufferType.ConstBuffer].Clear();
        }

        private void CbBind(NvGpuVmm Vmm, NvGpuPBEntry PBEntry)
        {
            int Stage = (PBEntry.Method - 0x904) >> 3;

            int Index = PBEntry.Arguments[0];

            bool Enabled = (Index & 1) != 0;

            Index = (Index >> 4) & 0x1f;

            long Position = MakeInt64From2xInt32(NvGpuEngine3dReg.ConstBufferAddress);

            long CbKey = Vmm.GetPhysicalAddress(Position);

            int Size = ReadRegister(NvGpuEngine3dReg.ConstBufferSize);

            if (!Gpu.Renderer.Buffer.IsCached(CbKey, Size))
            {
                Gpu.Renderer.Buffer.Create(CbKey, Size);
            }

            ConstBuffer Cb = ConstBuffers[Stage][Index];

            if (Cb.Position != Position || Cb.Enabled != Enabled || Cb.Size != Size)
            {
                ConstBuffers[Stage][Index].Position = Position;
                ConstBuffers[Stage][Index].Enabled = Enabled;
                ConstBuffers[Stage][Index].Size = Size;
            }
        }

        private float GetFlipSign(NvGpuEngine3dReg Reg)
        {
            return MathF.Sign(ReadRegisterFloat(Reg));
        }

        private long MakeInt64From2xInt32(NvGpuEngine3dReg Reg)
        {
            return
                (long)Registers[(int)Reg + 0] << 32 |
                (uint)Registers[(int)Reg + 1];
        }

        private void WriteRegister(NvGpuPBEntry PBEntry)
        {
            int ArgsCount = PBEntry.Arguments.Count;

            if (ArgsCount > 0)
            {
                Registers[PBEntry.Method] = PBEntry.Arguments[ArgsCount - 1];
            }
        }

        private int ReadRegister(NvGpuEngine3dReg Reg)
        {
            return Registers[(int)Reg];
        }

        private float ReadRegisterFloat(NvGpuEngine3dReg Reg)
        {
            return BitConverter.Int32BitsToSingle(ReadRegister(Reg));
        }

        private bool ReadRegisterBool(NvGpuEngine3dReg Reg)
        {
            return (ReadRegister(Reg) & 1) != 0;
        }

        private void WriteRegister(NvGpuEngine3dReg Reg, int Value)
        {
            Registers[(int)Reg] = Value;
        }

        private bool QueryKeyUpload(NvGpuVmm Vmm, long Key, long Size, NvGpuBufferType Type)
        {
            List<long> Uploaded = UploadedKeys[(int)Type];

            if (Uploaded.Contains(Key))
            {
                return false;
            }

            Uploaded.Add(Key);

            return Vmm.IsRegionModified(Key, Size, Type);
        }
    }
}