/*

* Copyright (c) 2004-2008 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

*

*/

using System;

using System.Collections.Generic;

using System.Text;

using SymbianStructuresLib.Arm.Registers;

using SymbianUtils.DataBuffer;

using SymbianUtils.DataBuffer.Entry;

namespace CrashDebuggerLib.Structures.UserContextTable

{

    internal class UserContextTableEntry

    {

        #region Enumerations

        public enum TType

		{

		    EUndefined,				/**< register is not available */

		    EOffsetFromSp,			/**< iOffset is offset from stack pointer */

		    EOffsetFromStackTop,	/**< iOffset is offset from stack top */

		    ESpPlusOffset,			/**< value = SP + offset */

        }

        #endregion

        #region Constructors

        public UserContextTableEntry()

        {

        }

        #endregion

        #region API

        public bool IsAvailable( bool aIsCurrentThread )

        {

            bool ret = false;

            //

            switch ( Type )

            {

            case TType.EOffsetFromSp:

                // Not allowed when it's the current thread

                ret = ( !aIsCurrentThread );

                break;

            case TType.EOffsetFromStackTop:

                // Always allowed

                ret = true;

                break;

            case TType.ESpPlusOffset:

                // Not allowed when it's the current thread

                ret = ( !aIsCurrentThread );

                break;

            default:

            case TType.EUndefined:

                break;

            }

            //

            return ret;

        }

        public uint Process( ArmRegister aSp, DataBuffer aStackData )

        {

            uint ret = 0;

            //

            switch ( Type )

            {

            case TType.EUndefined:

                throw new NotSupportedException();

            case TType.EOffsetFromSp:

                ret = UpdateUsingOffsetFromSp( aSp, aStackData );

                break;

            case TType.EOffsetFromStackTop:

                ret = UpdateUsingOffsetFromStackTop( aSp, aStackData );

                break;

            case TType.ESpPlusOffset:

                ret = UpdateUsingSpPlusOffset( aSp, aStackData );

                break;

            }

            //

            return ret;

        }

        #endregion

        #region Properties

        public TType Type

        {

            get { return iType; }

            set { iType = value; }

        }

        public byte Offset

        {

            get { return iOffset; }

            set { iOffset = value; }

        }

        public uint OffsetAsDWord

        {

            get { return (uint) Offset * 4; }

        }

        #endregion

        #region Internal methods

        private uint UpdateUsingOffsetFromSp( ArmRegister aSp, DataBuffer aStackData )

        {

            uint sp = aSp;

            uint offset = OffsetAsDWord;

            uint fetchAddr = offset + sp;

            DataBufferUint val = aStackData[ fetchAddr ];

            return val;

        }

        private uint UpdateUsingOffsetFromStackTop( ArmRegister aSp, DataBuffer aStackData )

        {

            uint stackTop = aStackData.Last.Address + 1;

            uint offset = OffsetAsDWord;

            uint fetchAddr = stackTop - offset;

            DataBufferUint val = aStackData[ fetchAddr ];

            return val;

        }

        private uint UpdateUsingSpPlusOffset( ArmRegister aSp, DataBuffer aStackData )

        {

            uint sp = aSp;

            uint offset = OffsetAsDWord;

            uint val = offset + sp;

            return val;

        }

        #endregion

        #region Data members

        private TType iType = TType.EUndefined;

        private byte iOffset = 0;

        #endregion

    }

}