using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using Cosmos.IL2CPU.Plugs;
using System.Runtime.InteropServices;
using Cosmos.Compiler.Assembler;

namespace Cosmos.IL2CPU
{
    public abstract class AppAssembler
    {
        protected ILOp[] mILOpsLo = new ILOp[256];
        protected ILOp[] mILOpsHi = new ILOp[256];

        private System.IO.TextWriter mLog;

        protected readonly Assembler mAssembler;
        public AppAssembler(Assembler assembler)
        {
            mAssembler = assembler;
            mLog = new System.IO.StreamWriter("Cosmos.Assembler.Log");
            InitILOps();
        }

        public Assembler Assembler
        {
            get
            {
                return mAssembler;
            }
        }

        protected virtual void MethodBegin(MethodInfo aMethod)
        {
            new Comment("---------------------------------------------------------");
            new Comment("Type: " + aMethod.MethodBase.DeclaringType.ToString());
            new Comment("Name: " + aMethod.MethodBase.Name);
            new Comment("Plugged: " + (aMethod.PlugMethod == null ? "No" : "Yes"));
        }

        protected virtual void MethodBegin(string aMethodName)
        {
            new Comment("---------------------------------------------------------");
            new Comment("Name: " + aMethodName);
        }

        protected virtual void MethodEnd(string aMethodName)
        {
            new Comment("End Method: " + aMethodName);
        }

        protected virtual void MethodEnd(MethodInfo aMethod)
        {
            new Comment("End Method: " + aMethod.MethodBase.Name);
        }

        public void ProcessMethod(MethodInfo aMethod, List<ILOpCode> aOpCodes)
        {
            // We check this here and not scanner as when scanner makes these
            // plugs may still have not yet been scanned that it will depend on.
            // But by the time we make it here, they have to be resolved.
            if (aMethod.Type == MethodInfo.TypeEnum.NeedsPlug && aMethod.PlugMethod == null)
            {
                throw new Exception("Method needs plug, but no plug was assigned.");
            }

            // todo: MtW: how to do this? we need some extra space.
            //		see ConstructLabel for extra info
            if (aMethod.UID > 0x00FFFFFF)
            {
                throw new Exception("For now, too much methods");
            }

            MethodBegin(aMethod);
            mAssembler.Stack.Clear();
            mLog.WriteLine("Method '{0}'", aMethod.MethodBase.GetFullName());
            mLog.Flush();
            if (aMethod.MethodAssembler != null)
            {
                mLog.WriteLine("Emitted using MethodAssembler", aMethod.MethodBase.GetFullName());
                mLog.Flush();
                var xAssembler = (AssemblerMethod)Activator.CreateInstance(aMethod.MethodAssembler);
                xAssembler.AssembleNew(mAssembler, aMethod.PluggedMethod);
            }
            else
            {
                foreach (var xOpCode in aOpCodes)
                {
                    uint xOpCodeVal = (uint)xOpCode.OpCode;
                    ILOp xILOp;
                    if (xOpCodeVal <= 0xFF)
                    {
                        xILOp = mILOpsLo[xOpCodeVal];
                    }
                    else
                    {
                        xILOp = mILOpsHi[xOpCodeVal & 0xFF];
                    }
                    //mLog.WriteLine ( "\t[" + xILOp.ToString() + "] \t Stack start: " + Stack.Count.ToString() );
                    mLog.WriteLine("\t{0} {1}", mAssembler.Stack.Count, xILOp.GetType().Name);
                    mLog.Flush();
                    BeforeOp(aMethod, xOpCode);
                    new Comment("[" + xILOp.ToString() + "]");
                    var xNextPosition = xOpCode.Position + 1;
                    #region Exception handling support code
                    ExceptionHandlingClause xCurrentHandler = null;
                    var xBody = aMethod.MethodBase.GetMethodBody();
                    // todo: add support for nested handlers using a stack or so..
                    foreach (ExceptionHandlingClause xHandler in xBody.ExceptionHandlingClauses)
                    {
                        if (xHandler.TryOffset > 0)
                        {
                            if (xHandler.TryOffset <= xNextPosition && (xHandler.TryLength + xHandler.TryOffset) > xNextPosition)
                            {
                                if (xCurrentHandler == null)
                                {
                                    xCurrentHandler = xHandler;
                                    continue;
                                }
                                else if (xHandler.TryOffset > xCurrentHandler.TryOffset && (xHandler.TryLength + xHandler.TryOffset) < (xCurrentHandler.TryLength + xCurrentHandler.TryOffset))
                                {
                                    // only replace if the current found handler is narrower
                                    xCurrentHandler = xHandler;
                                    continue;
                                }
                            }
                        }
                        if (xHandler.HandlerOffset > 0)
                        {
                            if (xHandler.HandlerOffset <= xNextPosition && (xHandler.HandlerOffset + xHandler.HandlerLength) > xNextPosition)
                            {
                                if (xCurrentHandler == null)
                                {
                                    xCurrentHandler = xHandler;
                                    continue;
                                }
                                else if (xHandler.HandlerOffset > xCurrentHandler.HandlerOffset && (xHandler.HandlerOffset + xHandler.HandlerLength) < (xCurrentHandler.HandlerOffset + xCurrentHandler.HandlerLength))
                                {
                                    // only replace if the current found handler is narrower
                                    xCurrentHandler = xHandler;
                                    continue;
                                }
                            }
                        }
                        if ((xHandler.Flags & ExceptionHandlingClauseOptions.Filter) > 0)
                        {
                            if (xHandler.FilterOffset > 0)
                            {
                                if (xHandler.FilterOffset <= xNextPosition)
                                {
                                    if (xCurrentHandler == null)
                                    {
                                        xCurrentHandler = xHandler;
                                        continue;
                                    }
                                    else if (xHandler.FilterOffset > xCurrentHandler.FilterOffset)
                                    {
                                        // only replace if the current found handler is narrower
                                        xCurrentHandler = xHandler;
                                        continue;
                                    }
                                }
                            }
                        }
                    }
                    #endregion
                    var xNeedsExceptionPush = (xCurrentHandler != null) && (((xCurrentHandler.HandlerOffset > 0 && xCurrentHandler.HandlerOffset == xOpCode.Position) || ((xCurrentHandler.Flags & ExceptionHandlingClauseOptions.Filter) > 0 && xCurrentHandler.FilterOffset > 0 && xCurrentHandler.FilterOffset == xOpCode.Position)) && (xCurrentHandler.Flags == ExceptionHandlingClauseOptions.Clause));
                    if (xNeedsExceptionPush)
                    {
                        Push(0);
                        mAssembler.Stack.Push(4, typeof(Exception));
                    }
                    xILOp.Execute(aMethod, xOpCode);
                    AfterOp(aMethod, xOpCode);
                    //mLog.WriteLine( " end: " + Stack.Count.ToString() );
                }
            }
            MethodEnd(aMethod);
        }

        //

        protected virtual void BeforeOp(MethodInfo aMethod, ILOpCode aOpCode)
        {
        }

        protected virtual void AfterOp(MethodInfo aMethod, ILOpCode aOpCode)
        {
        }

        protected abstract void InitILOps();

        protected virtual void InitILOps(Type aAssemblerBaseOp)
        {
            foreach (var xType in aAssemblerBaseOp.Assembly.GetExportedTypes())
            {
                if (xType.IsSubclassOf(aAssemblerBaseOp))
                {
                    var xAttribs = (OpCodeAttribute[])xType.GetCustomAttributes(typeof(OpCodeAttribute), false);
                    foreach (var xAttrib in xAttribs)
                    {
                        var xOpCode = (ushort)xAttrib.OpCode;
                        var xCtor = xType.GetConstructor(new Type[] { typeof(Assembler) });
                        var xILOp = (ILOp)xCtor.Invoke(new Object[] { Assembler });
                        if (xOpCode <= 0xFF)
                        {
                            mILOpsLo[xOpCode] = xILOp;
                        }
                        else
                        {
                            mILOpsHi[xOpCode & 0xFF] = xILOp;
                        }
                    }
                }
            }
        }

        protected abstract void Push(uint aValue);
        protected abstract void Push(string aLabelName);
        protected abstract void Call(MethodBase aMethod);
        protected abstract void Move(string aDestLabelName, int aValue);
        protected abstract void Jump(string aLabelName);
        protected abstract int GetVTableEntrySize();


        public const string InitVMTCodeLabel = "___INIT__VMT__CODE____";
        public void GenerateVMTCode(HashSet<Type> aTypesSet, HashSet<MethodBase> aMethodsSet, Func<Type, uint> aGetTypeID, Func<MethodBase, uint> aGetMethodUID)
        {
            // initialization
            MethodBegin(InitVMTCodeLabel);
            {
                var xSetTypeInfoRef = VTablesImplRefs.SetTypeInfoRef;
                var xSetMethodInfoRef = VTablesImplRefs.SetMethodInfoRef;
                var xLoadTypeTableRef = VTablesImplRefs.LoadTypeTableRef;
                var xTypesFieldRef = VTablesImplRefs.VTablesImplDef.GetField("mTypes",
                                                                                   BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance);
                string xTheName = DataMember.GetStaticFieldName(xTypesFieldRef);
                DataMember xDataMember = (from item in Assembler.CurrentInstance.DataMembers
                                          where item.Name == xTheName
                                          select item).FirstOrDefault();
                if (xDataMember != null)
                {
                    Assembler.CurrentInstance.DataMembers.Remove((from item in Assembler.CurrentInstance.DataMembers
                                                                   where item == xDataMember
                                                                   select item).First());
                }
                var xData = new byte[16 + (aTypesSet.Count * GetVTableEntrySize())];
                var xTemp = BitConverter.GetBytes(aGetTypeID(typeof(Array)));
                xTemp = BitConverter.GetBytes(0x80000002);
                Array.Copy(xTemp, 0, xData, 4, 4);
                xTemp = BitConverter.GetBytes(aTypesSet.Count);
                Array.Copy(xTemp, 0, xData, 8, 4);
                xTemp = BitConverter.GetBytes(GetVTableEntrySize());
                Array.Copy(xTemp, 0, xData, 12, 4);
                Assembler.CurrentInstance.DataMembers.Add(new DataMember(xTheName + "__Contents", xData));
                Assembler.CurrentInstance.DataMembers.Add(new DataMember(xTheName, ElementReference.New(xTheName + "__Contents")));
#if VMT_DEBUG
        using (var xVmtDebugOutput = XmlWriter.Create(@"e:\vmt_debug.xml"))
        {
            xVmtDebugOutput.WriteStartDocument();
            xVmtDebugOutput.WriteStartElement("VMT");
#endif
                //Push((uint)aTypesSet.Count);
                //Call(xLoadTypeTableRef);
                foreach (var xType in aTypesSet)
                {
#if VMT_DEBUG
                xVmtDebugOutput.WriteStartElement("Type");
                xVmtDebugOutput.WriteAttributeString("TypeId", aGetTypeID(xType).ToString());
                if (xType.BaseType != null)
                {
                    xVmtDebugOutput.WriteAttributeString("BaseTypeId", aGetTypeID(xType.BaseType).ToString());
                }
                xVmtDebugOutput.WriteAttributeString("Name", xType.FullName);
#endif
                    // value contains true if the method is an interface method definition
                    SortedList<MethodBase, bool> xEmittedMethods = new SortedList<MethodBase, bool>(new MethodBaseComparer());
                    foreach (MethodBase xMethod in xType.GetMethods(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance))
                    {
                        if (aMethodsSet.Contains(xMethod))//) && !xMethod.IsAbstract)
                        {
                            xEmittedMethods.Add(xMethod, false);
                        }
                    }
                    foreach (MethodBase xCtor in xType.GetConstructors(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance))
                    {
                        if (aMethodsSet.Contains(xCtor))// && !xCtor.IsAbstract)
                        {
                            xEmittedMethods.Add(xCtor, false);
                        }
                    }
                    foreach (var xIntf in xType.GetInterfaces())
                    {
                        foreach (var xMethodIntf in xIntf.GetMethods())
                        {
                            var xActualMethod = xType.GetMethod(xIntf.FullName + "." + xMethodIntf.Name,
                                                                (from xParam in xMethodIntf.GetParameters()
                                                                 select xParam.ParameterType).ToArray());

                            if (xActualMethod == null)
                            {
                                // get private implemenation
                                xActualMethod = xType.GetMethod(xMethodIntf.Name,
                                                                (from xParam in xMethodIntf.GetParameters()
                                                                 select xParam.ParameterType).ToArray());
                            }
                            if (xActualMethod == null)
                            {
                                try
                                {
                                    var xMap = xType.GetInterfaceMap(xIntf);
                                    for (int k = 0; k < xMap.InterfaceMethods.Length; k++)
                                    {
                                        if (xMap.InterfaceMethods[k] == xMethodIntf)
                                        {
                                            xActualMethod = xMap.TargetMethods[k];
                                            break;
                                        }
                                    }
                                }
                                catch
                                {
                                }
                            }
                            if (aMethodsSet.Contains(xMethodIntf))
                            {
                                if (!xEmittedMethods.ContainsKey(xMethodIntf))
                                {
                                    xEmittedMethods.Add(xMethodIntf,
                                                        true);
                                }
                            }

                        }
                    }
                    if (!xType.IsInterface)
                    {
                        Push(aGetTypeID(xType));
                    }
                    int? xBaseIndex = null;
                    if (xType.BaseType == null)
                    {
                        xBaseIndex = (int)aGetTypeID(xType);
                    }
                    else
                    {
                        for (int t = 0; t < aTypesSet.Count; t++)
                        {
                            // todo: optimize check
                            var xItem = aTypesSet.Skip(t).First();
                            if (xItem.ToString() == xType.BaseType.ToString())
                            {
                                xBaseIndex = (int)aGetTypeID(xItem);
                                break;
                            }
                        }
                    }
                    if (xBaseIndex == null)
                    {
                        throw new Exception("Base type not found!");
                    }
                    for (int x = xEmittedMethods.Count - 1; x >= 0; x--)
                    {
                        if (!aMethodsSet.Contains(xEmittedMethods.Keys[x]))
                        {
                            xEmittedMethods.RemoveAt(x);
                        }
                    }
                    if (!xType.IsInterface)
                    {
                        Move("VMT__TYPE_ID_HOLDER__" + DataMember.FilterStringForIncorrectChars(MethodInfoLabelGenerator.GetFullName(xType) + " ASM_IS__" + xType.Assembly.GetName().Name), (int)aGetTypeID(xType));
                        Assembler.CurrentInstance.DataMembers.Add(
                            new DataMember("VMT__TYPE_ID_HOLDER__" + DataMember.FilterStringForIncorrectChars(MethodInfoLabelGenerator.GetFullName(xType) + " ASM_IS__" + xType.Assembly.GetName().Name), new int[] { (int)aGetTypeID(xType) }));
                        Push((uint)xBaseIndex.Value);
                        xData = new byte[16 + (xEmittedMethods.Count * 4)];
                        xTemp = BitConverter.GetBytes(aGetTypeID(typeof(Array)));
                        Array.Copy(xTemp, 0, xData, 0, 4);
                        xTemp = BitConverter.GetBytes(0x80000002); // embedded array
                        Array.Copy(xTemp, 0, xData, 4, 4);
                        xTemp = BitConverter.GetBytes(xEmittedMethods.Count); // embedded array
                        Array.Copy(xTemp, 0, xData, 8, 4);
                        xTemp = BitConverter.GetBytes(4); // embedded array
                        Array.Copy(xTemp, 0, xData, 12, 4);
                        string xDataName = "____SYSTEM____TYPE___" + DataMember.FilterStringForIncorrectChars(MethodInfoLabelGenerator.GetFullName(xType) + " ASM_IS__" + xType.Assembly.GetName().Name) + "__MethodIndexesArray";
                        Assembler.CurrentInstance.DataMembers.Add(new DataMember(xDataName, xData));
                        Push(xDataName);
                        xDataName = "____SYSTEM____TYPE___" + DataMember.FilterStringForIncorrectChars(MethodInfoLabelGenerator.GetFullName(xType) + " ASM_IS__" + xType.Assembly.GetName().Name) + "__MethodAddressesArray";
                        Assembler.CurrentInstance.DataMembers.Add(new DataMember(xDataName, xData));
                        Push(xDataName);
                        xData = new byte[16 + Encoding.Unicode.GetByteCount(xType.FullName + ", " + xType.Module.Assembly.GetName().FullName)];
                        xTemp = BitConverter.GetBytes(aGetTypeID(typeof(Array)));
                        Array.Copy(xTemp, 0, xData, 0, 4);
                        xTemp = BitConverter.GetBytes(0x80000002); // embedded array
                        Array.Copy(xTemp, 0, xData, 4, 4);
                        xTemp = BitConverter.GetBytes((xType.FullName + ", " + xType.Module.Assembly.GetName().FullName).Length);
                        Array.Copy(xTemp, 0, xData, 8, 4);
                        xTemp = BitConverter.GetBytes(2); // embedded array
                        Array.Copy(xTemp, 0, xData, 12, 4);
                        xDataName = "____SYSTEM____TYPE___" + DataMember.FilterStringForIncorrectChars(MethodInfoLabelGenerator.GetFullName(xType) + " ASM_IS__" + xType.Assembly.GetName().Name);
                        Assembler.CurrentInstance.DataMembers.Add(new DataMember(xDataName, xData));
                        Push("0" + xEmittedMethods.Count.ToString("X") + "h");
                        Call(xSetTypeInfoRef);
                    }
                    for (int j = 0; j < xEmittedMethods.Count; j++)
                    {
                        MethodBase xMethod = xEmittedMethods.Keys[j];
#if VMT_DEBUG
                    xVmtDebugOutput.WriteStartElement("Method");
                    xVmtDebugOutput.WriteAttributeString("Id", aGetMethodUID(xMethod).ToString());
                    xVmtDebugOutput.WriteAttributeString("Name", xMethod.GetFullName());
                    xVmtDebugOutput.WriteEndElement();
#endif
                        var xMethodId = aGetMethodUID(xMethod);
                        if (!xType.IsInterface)
                        {
                            if (xEmittedMethods.Values[j])
                            {
                                var xNewMethod = xType.GetMethod(xMethod.DeclaringType.FullName + "." + xMethod.Name,
                                                                    (from xParam in xMethod.GetParameters()
                                                                     select xParam.ParameterType).ToArray());

                                if (xNewMethod == null)
                                {
                                    // get private implemenation
                                    xNewMethod = xType.GetMethod(xMethod.Name,
                                                                    (from xParam in xMethod.GetParameters()
                                                                     select xParam.ParameterType).ToArray());
                                }
                                if (xNewMethod == null)
                                {
                                    try
                                    {
                                        var xMap = xType.GetInterfaceMap(xMethod.DeclaringType);
                                        for (int k = 0; k < xMap.InterfaceMethods.Length; k++)
                                        {
                                            if (xMap.InterfaceMethods[k] == xMethod)
                                            {
                                                xNewMethod = xMap.TargetMethods[k];
                                                break;
                                            }
                                        }
                                    }
                                    catch
                                    {
                                    }
                                }
                                xMethod = xNewMethod;
                            }

                            Push((uint)aGetTypeID(xType));
                            Push((uint)j);

                            Push((uint)xMethodId);
                            if (xMethod.IsAbstract)
                            {
                                // abstract methods dont have bodies, oiw, are not emitted
                                Push(0);
                            }
                            else
                            {
                                Push(ILOp.GetMethodLabel(xMethod));
                            }
                            Push(0);
                            Call(VTablesImplRefs.SetMethodInfoRef);
                        }
                    }
#if VMT_DEBUG
                xVmtDebugOutput.WriteEndElement(); // type
#endif
                }
#if VMT_DEBUG
                    xVmtDebugOutput.WriteEndElement(); // types
                    xVmtDebugOutput.WriteEndDocument();
        }
#endif
            }
            MethodEnd(InitVMTCodeLabel);
        }

        public void ProcessField(FieldInfo aField)
        {
            string xFieldName = MethodInfoLabelGenerator.GetFullName(aField);
            xFieldName = DataMember.GetStaticFieldName(aField);
            if (Assembler.CurrentInstance.DataMembers.Count(x => x.Name == xFieldName) == 0)
            {
                var xItemList = (from item in aField.GetCustomAttributes(false)
                                 where item.GetType().FullName == "ManifestResourceStreamAttribute"
                                 select item).ToList();

                object xItem = null;
                if (xItemList.Count > 0)
                    xItem = xItemList[0];
                string xManifestResourceName = null;
                if (xItem != null)
                {
                    var xItemType = xItem.GetType();
                    xManifestResourceName = (string)xItemType.GetField("ResourceName").GetValue(xItem);
                }
                if (xManifestResourceName != null)
                {
                    // todo: add support for manifest streams again
                    //RegisterType(xCurrentField.FieldType);
                    //string xFileName = Path.Combine(mOutputDir,
                    //                                (xCurrentField.DeclaringType.Assembly.FullName + "__" + xManifestResourceName).Replace(",",
                    //                                                                                                                       "_") + ".res");
                    //using (var xStream = xCurrentField.DeclaringType.Assembly.GetManifestResourceStream(xManifestResourceName)) {
                    //    if (xStream == null) {
                    //        throw new Exception("Resource '" + xManifestResourceName + "' not found!");
                    //    }
                    //    using (var xTarget = File.Create(xFileName)) {
                    //        // todo: abstract this array code out.
                    //        xTarget.Write(BitConverter.GetBytes(Engine.RegisterType(Engine.GetType("mscorlib",
                    //                                                                               "System.Array"))),
                    //                      0,
                    //                      4);
                    //        xTarget.Write(BitConverter.GetBytes((uint)InstanceTypeEnum.StaticEmbeddedArray),
                    //                      0,
                    //                      4);
                    //        xTarget.Write(BitConverter.GetBytes((int)xStream.Length), 0, 4);
                    //        xTarget.Write(BitConverter.GetBytes((int)1), 0, 4);
                    //        var xBuff = new byte[128];
                    //        while (xStream.Position < xStream.Length) {
                    //            int xBytesRead = xStream.Read(xBuff, 0, 128);
                    //            xTarget.Write(xBuff, 0, xBytesRead);
                    //        }
                    //    }
                    //}
                    //mAssembler.DataMembers.Add(new DataMember("___" + xFieldName + "___Contents",
                    //                                          "incbin",
                    //                                          "\"" + xFileName + "\""));
                    //mAssembler.DataMembers.Add(new DataMember(xFieldName,
                    //                                          "dd",
                    //                                          "___" + xFieldName + "___Contents"));
                    throw new NotImplementedException();
                }
                else
                {
                    uint xTheSize;
                    //string theType = "db";
                    Type xFieldTypeDef = aField.FieldType;
                    if (!xFieldTypeDef.IsClass || xFieldTypeDef.IsValueType)
                    {
                        xTheSize = GetSizeOfType(aField.FieldType);
                    }
                    else
                    {
                        xTheSize = 4;
                    }
                    byte[] xData = new byte[xTheSize];
                    try
                    {
                        object xValue = aField.GetValue(null);
                        if (xValue != null)
                        {
                            try
                            {
                                xData = new byte[xTheSize];
                                if (xValue.GetType().IsValueType)
                                {
                                    for (int x = 0; x < xTheSize; x++)
                                    {
                                        xData[x] = Marshal.ReadByte(xValue,
                                                                    x);
                                    }
                                }
                            }
                            catch
                            {
                            }
                        }
                    }
                    catch
                    {
                    }
                    Assembler.CurrentInstance.DataMembers.Add(new DataMember(xFieldName, xData));
                }
            }
        }

        public abstract uint GetSizeOfType(Type aType);

        public abstract void EmitEntrypoint(MethodBase aEntrypoint, IEnumerable<MethodBase> aMethods);

        protected abstract void Ldarg(MethodInfo aMethod, int aIndex);
        protected abstract void Ldflda(MethodInfo aMethod, string aFieldId);
        protected abstract void Call(MethodInfo aMethod, MethodInfo aTargetMethod);
        protected abstract void Pop();

        internal void GenerateMethodForward(MethodInfo aFrom, MethodInfo aTo)
        {
            // todo: completely get rid of this kind of trampoline code
            MethodBegin(aFrom);
            {
                var xParams = aTo.MethodBase.GetParameters().ToArray();

                if (aTo.MethodAssembler != null)
                {
                    xParams = aFrom.MethodBase.GetParameters();
                }

                //if (aFrom.MethodBase.GetParameters().Length > 0 || !aFrom.MethodBase.IsStatic) {
                //  Ldarg(aFrom, 0);
                //  Pop();
                //}

                int xCurParamIdx = 0;
                if (!aFrom.MethodBase.IsStatic)
                {
                    Ldarg(aFrom, 0);
                    xCurParamIdx++;
                    if (aTo.MethodAssembler == null)
                    {
                        xParams = xParams.Skip(1).ToArray();
                    }
                }
                foreach (var xParam in xParams)
                {
                    FieldAccessAttribute xFieldAccessAttrib = null;
                    foreach (var xAttrib in xParam.GetCustomAttributes(typeof(FieldAccessAttribute), true))
                    {
                        xFieldAccessAttrib = xAttrib as FieldAccessAttribute;
                    }

                    if (xFieldAccessAttrib != null)
                    {
                        // field access                                                                                        
                        new Comment("Loading address of field '" + xFieldAccessAttrib.Name + "'");
                        Ldarg(aFrom, 0);
                        Ldflda(aFrom, xFieldAccessAttrib.Name);
                    }
                    else
                    {
                        // normal field access
                        new Comment("Loading parameter " + xCurParamIdx);
                        Ldarg(aFrom, xCurParamIdx);
                        xCurParamIdx++;
                    }
                }
                Call(aFrom, aTo);
            }
            MethodEnd(aFrom);
        }
    
    }
}