/*

* Copyright (c) 2009 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 System.IO;

using SymbianStructuresLib.Version;

namespace SymbianImageLib.ROM.Structures

{

    internal class SRomPageInfo

    {

        #region Enumerations

        public enum TSymbianCompressionType

        {

            ENoCompression = 0,

            EBytePair,

        }

        #endregion

        #region Static constructors

        public static SRomPageInfo New( Stream aStream, uint aOffsetToStartOfRomData )

        {

            byte[] data = new byte[ Size ];

            aStream.Read( data, 0, data.Length );

            return new SRomPageInfo( data, aOffsetToStartOfRomData );

        }

        #endregion

        #region Constructors

        private SRomPageInfo( byte[] aArray, uint aOffsetToStartOfRomData )

        {

            uint delta = 0;

            //

            iDataStart = aOffsetToStartOfRomData + ReadUint( aArray, ref delta );

            iDataSize = ReadUshort( aArray, ref delta );

            iCompressionType = (TSymbianCompressionType) aArray[ delta++ ];

            iPagingAttributes = (TAttributes) aArray[ delta++ ];

        }

        #endregion

        #region Constants

        public const int KPageSize = 0x1000;

        #endregion

        #region Properties

        public static uint Size

        {

            get { return 8; }

        }

        public bool IsPageable

        {

            get { return ( iPagingAttributes & TAttributes.EPageable ) == TAttributes.EPageable; }

        }

        public TSymbianCompressionType CompressionType

        {

            get

            { 

                // Rather frustratingly, even unpageable areas of the ROM still report their

                // compression type as "byte pair". We must zero this out, since they are

                // definitely not compressed.

                if ( !IsPageable )

                {

                    return TSymbianCompressionType.ENoCompression;

                }

                //

                return iCompressionType;

            }

        }

        public uint DataStart

        {

            get { return iDataStart; }

        }

        public uint DataSize

        {

            get { return iDataSize; }

        }

        #endregion

        #region Internal enumerations

        [Flags]

        private enum TAttributes

        {

            EPageable = 1 << 0

        }

        #endregion

        #region Internal methods

        private static uint ReadUint( byte[] aArray, ref uint aOffset )

        {

            uint ret = 0;

            //

            ret += (uint) ( aArray[ aOffset + 0 ] << 00 );

            ret += (uint) ( aArray[ aOffset + 1 ] << 08 );

            ret += (uint) ( aArray[ aOffset + 2 ] << 16 );

            ret += (uint) ( aArray[ aOffset + 3 ] << 24 );

            //

            aOffset += 4;

            //

            return ret;

        }

        private static ushort ReadUshort( byte[] aArray, ref uint aOffset )

        {

            ushort ret = 0;

            //

            ret += (ushort) ( aArray[ aOffset + 0 ] << 00 );

            ret += (ushort) ( aArray[ aOffset + 1 ] << 08 );

            //

            aOffset += 2;

            //

            return ret;

        }

        #endregion

        #region Data members

        private uint iDataStart;

        private ushort iDataSize;

        private TSymbianCompressionType iCompressionType;

        private TAttributes iPagingAttributes;

        #endregion

    }

}